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Purpose: This study aimed to quantify Aggregatibacter actinomycetemcomitans (A.a) and Porphyromonas gingivalis (P.g) from the mouth of head and neck irradiated and cancer-free patients. Methods: Information such as age, presence of tongue coating, salivary flow, and biofilm were collected from head and neck irradiated patients (Group 1) and compared the results with a group of cancer-free individuals (Group 2). The presence of tongue coating was clinically examined. Sialometry was performed through a stimulating technique by chewing paraffin. Microbiological samples were collected from buccal and labial mucosa and tongue dorsum. Subsequently, the samples were processed and analyzed by qPCR to detect the presence and quantify the bacteria. Results: There was a statistical difference in the quantity of bacteria among the 24 individuals in Group 1 (A.a, 2817 ± 8718; P.g, 3145 ± 11297) and 26 individuals in Group 2 (A.a, 133996 ± 398545; P.g, 60 ± 195) regarding tongue coating (Group 1, A.a 2194.6 ± 4641.5; Group 2, A.a 92767.8 ± 333385.7) and salivary volume (Group 1, 0.69 mL; Group 2, 3.09 mL). The linear regression analysis found that the variable group was the main responsible for the difference in the quantity of periodontal pathogens (p-value < 0.001). There was no statistical difference in the amount of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis between totally edentulous and partially edentulous (with 12 or fewer teeth) patients. Conclusion: Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were present in significant amounts in patients of both groups, with a greater quantity in cancer-free individuals. [ABSTRACT FROM AUTHOR]

This review addresses the recent World Workshop Consensus Conference (WWCC) decision to eliminate Localized Aggressive Periodontitis (LAgP) in young adults as a distinct form of periodontitis. A "Consensus" implies widespread, if not unanimous, agreement among participants. However, a significant number of attendees were opposed to the elimination of the LAgP classification. The substantial evidence supporting a unique diagnosis for LAgP includes the (1) incisor/molar pattern of disease, (2) young age of onset, (3) rapid progression of attachment and bone loss, (4) familial aggregation across multiple generations, and (5) defined consortium of microbiological risk factors including Aggregatibacter actinomycetemcomitans. Distinctive clinical signs and symptoms of LAgP are presented, and the microbial subgingival consortia that precede the onset of signs and symptoms are described. Using Bradford–Hill guidelines to assess causation, well-defined longitudinal studies support the unique microbial consortia, including A. actinomycetemcomitans as causative for LAgP. To determine the effects of the WWCC elimination of LAgP on research, we searched three publication databases and discovered a clear decrease in the number of new publications addressing LAgP since the new WWCC classification. The negative effects of the WWCC guidelines on both diagnosis and treatment success are presented. For example, due to the localized nature of LAgP, the practice of averaging mean pocket depth reduction or attachment gain across all teeth masks major changes in disease recovery at high-risk tooth sites. Reinstating LAgP as a distinct disease entity is proposed, and an alternative or additional way of measuring treatment success is recommended based on an assessment of the extension of the time to relapse of subgingival re-infection. The consequences of the translocation of oral microbes to distant anatomical sites due to ignoring relapse frequency are also discussed. Additional questions and future directions are also presented. [ABSTRACT FROM AUTHOR]

The periodontal disease pathobiont Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) may exert a range of detrimental effects on periodontal diseases in general and, more specifically, with the initiation and progression of Localized Stage III Grade C periodontitis (molar–incisor pattern). In this review of the biogeography of this pathobiont, the full range of geographical scales for A. actinomycetemcomitans, from global origins and transmission to local geographical regions, to more locally exposed probands and families, to the individual host, down to the oral cavity, and finally, to spatial interactions with other commensals and pathobionts within the plaque biofilms at the micron/nanoscale, are reviewed. Using the newest technologies in genetics, imaging, in vitro cultures, and other research disciplines, investigators may be able to gain new insights to the role of this pathobiont in the unique initial destructive patterns of Localized Stage III Grade C periodontitis. These findings may incorporate the unique features of the microbiome that are influenced by variations in the geographic environment within the entire mouth. Additional insights into the geographic distribution of molar–incisor periodontal breakdown for Localized Stage III Grade C periodontitis may derive from the spatial interactions between A. actinomycetemcomitans and other pathobionts such as Porphyromonas gingivalis, Filifactor aclocis, and commensals such as Streptococcus gordonii. In addition, while the association of A. actinomycetemcomitans in systemic diseases is limited at the present time, future studies into possible periodontal disease–systemic disease links may also find A. actinomycetemcomitans and its geographical interactions with other microbiome members to provide important clues as to implications of pathobiological communications. [ABSTRACT FROM AUTHOR]

Adolescent carriers of the Aggregatibacter actinomycetemcomitans JP2 genotype have an increased risk of developing periodontitis, due to the bacterium's high leukotoxin (LtxA) production. LtxA contributes to marginal bone loss by killing immunity cells, thus activating the proinflammatory interleukin-1β (IL-1β), which, in turn, activates the osteoclasts. A possible strategy to prevent periodontitis might be to neutralize LtxA in JP2-infected individuals. The aim of this study was to investigate whether extracts from Matcha or Guava leaves can prolong the viability of macrophages in cell cultures by neutralizing the highly leukotoxic JP2 genotype bacteria. The A. actinomycetemcomitans JP2 genotype was pretreated with extracts from either Matcha or Guava leaves. Later, the extracts were rinsed off, before JP2 bacteria were exposed to macrophage cell cultures. The experiment was repeated, where JP2 bacteria were persistently treated with the extracts instead, i.e., the extracts were not rinsed off. The macrophage viability after bacterial exposure was analyzed and compared with that of macrophages exposed to untreated JP2 bacteria. IL-1β secretion in the cell culture medium was quantified in all group samples. Pretreatment of the A. actinomycetemcomitans JP2 genotype with Matcha or Guava leaf extracts moderately neutralized LtxA activity, which resulted in prolonged macrophage viability and decreased IL-1β secretion. These effects of prolonged macrophage viability were enhanced when extracts were persistently present during the exposure period. The results indicate that Matcha and Guava leaf extracts have effects on the virulence of the A. actinomycetemcomitans JP2 genotype that may be useful in future treatment strategies to prevent periodontitis in JP2 bacterium carriers. [ABSTRACT FROM AUTHOR]

Adolescent carriers of the Aggregatibacter actinomycetemcomitans JP2 genotype have an increased risk of developing periodontitis, due to the bacterium’s high leukotoxin (LtxA) production. LtxA contributes to marginal bone loss by killing immunity cells, thus activating the proinflammatory interleukin-1β (IL-1β), which, in turn, activates the osteoclasts. A possible strategy to prevent periodontitis might be to neutralize LtxA in JP2-infected individuals. The aim of this study was to investigate whether extracts from Matcha or Guava leaves can prolong the viability of macrophages in cell cultures by neutralizing the highly leukotoxic JP2 genotype bacteria. The A. actinomycetemcomitans JP2 genotype was pretreated with extracts from either Matcha or Guava leaves. Later, the extracts were rinsed off, before JP2 bacteria were exposed to macrophage cell cultures. The experiment was repeated, where JP2 bacteria were persistently treated with the extracts instead, i.e., the extracts were not rinsed off. The macrophage viability after bacterial exposure was analyzed and compared with that of macrophages exposed to untreated JP2 bacteria. IL-1β secretion in the cell culture medium was quantified in all group samples. Pretreatment of the A. actinomycetemcomitans JP2 genotype with Matcha or Guava leaf extracts moderately neutralized LtxA activity, which resulted in prolonged macrophage viability and decreased IL-1β secretion. These effects of prolonged macrophage viability were enhanced when extracts were persistently present during the exposure period. The results indicate that Matcha and Guava leaf extracts have effects on the virulence of the A. actinomycetemcomitans JP2 genotype that may be useful in future treatment strategies to prevent periodontitis in JP2 bacterium carriers.

Objective: The objective of this study was to evaluate the antibacterial efficacy of wax apple (Syzygium samarangense) fruit extracts (aqueous and ethanol) against Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans. Methodology: The stock solution was prepared for microbial analysis (100 mg/ml). A disc diffusion test to determine the zone of inhibition and the serial broth dilution test to determine the minimum inhibitory concentration were done to assess the antimicrobial activity. Data obtained were appraised observationally and interpreted. Results: When assessed for antibacterial activity of extracts by disc diffusion method, both aqueous and ethanolic extracts did not show a zone of inhibition on P. gingivalis and A. actinomycetemcomitans. However, the aqueous extract showed an inhibition zone of 8 mm at the concentration of 50 and 75 µl/ml against F. nucleatum. Similarly, the ethanolic extract showed an inhibition zone of 8 mm at 50 µl/ml and 9 mm at 75 µl/ml volume against F. nucleatum. When assessed for antibacterial activity of extracts by serial broth dilution method, only P. gingivalis (both aqueous and ethanolic extracts at 50 µg/ml) and F. nucleatum (aqueous extracts at 1. 6 µg/ml and ethanolic extract at 0.4 µg/ml) exhibited antibacterial effect, whereas A. actinomycetemcomitans was completely resistant to both extracts at all the concentrations. Conclusion: In the present in vitro study, S. samarangense (wax apple) showed its antibacterial activity against F. nucleatum only by exhibiting MIC at 1.6 µg/ml for aqueous and 0.4 µg/ml for ethanolic extract, but no antibacterial activity was shown against P. gingivalis and A. actinomycetemcomitans.

Background Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are pathogenic bacteria of the oral cavity that cause various diseases such as periodontitis and endodontics. These bacteria are easily resistant to antibiotics. Photodynamic inactivation (PDI) is a method of inactivating microorganisms that utilizes light to activate a photosensitizer agent (PS) that produces reactive oxygen species causing cell lysis. Methods This study used the PDI method with a 405 nm diode laser at various energy density with the addition PS curcumin or chlorophyll Alfalfa, as much as 1.6 mg/ml on A. actinomycetemcomitans and E. faecalis bacteria. Results The study on E. faecalis bacteria showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of E. faecalis bacteria death 36.7% without PS, 69.30% with the addition of chlorophyll Medicago sativa L and 89.42% with the addition of curcumin. Meanwhile, the bacteria A. actinomycetemcomitans showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of bacterial death 35.81% without PS, 64.39% with the addition of chlorophyll Medicago sativa L and 89.82% with the addition of curcumin. PS was critical to the success of the PDI. Conclusions The addition of PS curcumin increased the effectiveness of reducing bacteria E. faecalis and A. actinomycetemcomitans compared to chlorophyll Medicago sativa L.

To assess and compare the anti-microbial efficacy of 445 nm and 970 nm diode laser on mixed species biofilm of Aggregatibacter actinomycetemcomitans [A.a] and Porphyromonas gingivalis [P.g] cultured on machined pure titanium discs. A total of 65 machined pure titanium discs with no surface modifications with a 10-mm diameter and a 2-mm height were sterilized by autoclaving at 121 °C for 15 min and incubated with the commercially available bacterial strains ATCC(American Type Culture Collection- P.g 33277 and A.a 29522)mixture of Aggregatibacter actinomycetemcomitans(A.a) and Porphyromonas gingivalis(P.g).After a 2-week incubation period with the mixture of bacteria to develop a mixed species biofilm, the discs were divided into three groups: (1) no treatment (control), (2) 445 nm laser (test), (3) 970 nm laser (test). For each laser wavelength (445 and 970 nm), the discs were exposed to 1.0 W and 2.0 W in continuous wave mode for the times points of 15, 30, and 60 s. The antimicrobial efficacy was assessed by qPCR. A significant reduction in the levels of both species of bacteria was observed between control and the laser intervention groups. A higher efficacy for the 445 nm diode laser against Porphyromonas gingivalis and a similar efficacy against Aggregatibacter actinomycetemcomitans was observed as compared to the 970 nm group. 445 nm wavelength represents a potential and effective laser wavelength which can be used for the management of peri-implant infection. The present study findings also need to be further validated through clinical interventional trials. [ABSTRACT FROM AUTHOR]

Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis are key pathogens involved in peri-implantitis, a major cause of dental implant failure. The rise of antibiotic resistance necessitates the exploration of alternative treatments. Phyllanthus niruri L. is a medicinal plant known for its potential antibacterial properties. This study aimed to evaluate the antibacterial efficacy of Phyllanthus niruri L. leaf extract by determining its Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. The phytochemical composition of Phyllanthus niruri L. leaf extract was analyzed, and its antibacterial activity was assessed using serial dilution methods on agar media. Colony-forming units (CFU) were counted to determine MIC and MBC values. Statistical analyses, including Shapiro-Wilk, Bartlett, and Tukey HSD tests, were performed to validate the results. Results: Phytochemical analysis revealed the presence of flavonoids, alkaloids, tannins/phenols, and triterpenoids, with the absence of saponins. The MIC for both Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis was determined to be 6.25%, where bacterial growth was reduced by 63%. The MBC was established at 12.5%, at which no bacterial growth was observed. Statistical tests confirmed the significance of these findings (p < 0.05). Phyllanthus niruri L. leaf extract demonstrates significant antibacterial activity against Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis, with potential application as a natural alternative in the treatment of peri-implantitis. Further research is recommended to explore its clinical efficacy and possible synergistic effects with conventional therapies. [ABSTRACT FROM AUTHOR]

Aggressive forms of periodontitis, especially in young patients, are often associated with an increased proportion of the Gram-negative bacterium Aggregatibacter actinomycetemcomitans of the microbiota of the affected periodontal sites. One of the virulence factors of A. actinomycetemcomitans is a leukotoxin (LtxA) that induces a pro-inflammatory cell death process in leukocytes. A. actinomycetemcomitans exhibits a large genetic diversity and different genotypes vary in LtxA production capacity. The genotype JP2 is a heavy LtxA producer due to a 530-base pair deletion in the promoter for the toxin genes, and this trait has been associated with an increased pathogenic potential. The present study focused on the production and release of LtxA by different A. actinomycetemcomitans genotypes and serotypes under various growth conditions. Four different strains of this bacterium were cultured in two different culture broths, and the amount of LtxA bound to the bacterial surface or released into the broths was determined. The cultures were examined during the logarithmic and the early stationary phases of growth. The JP2 genotype exhibited the highest LtxA production among the strains tested, and production was not affected by the growth phase. The opposite was observed with the other strains. The composition of the culture broth had no effect on the growth pattern of the tested strains. However, the abundant release of LtxA from the bacterial surface into the culture broth was found in the presence of horse serum. Besides confirming the enhanced leucotoxicity of the JP2 genotype, the study provides new data on LtxA production in the logarithmic and stationary phases of growth and the effect of media composition on the release of the toxin from the bacterial membrane. [ABSTRACT FROM AUTHOR]

Aggregatibacter actinomycetemcomitans (A. actinomycetecomitans) is a Gram-negative bacterial species that is an essential component of the oral microbiota. Due to its aggregative properties, it plays a role in the pathogenesis of human diseases. The presence of the surface proteins Fim, Briae, and microvesicles enables the bacterium to adhere to the epithelial surface and the tooth's surface. The presence of leukotoxin A (LtxA), which plays an important role in the pathogenicity of the bacterium, has been associated with both periodontitis and the etiology of rheumatoid arthritis (RA). A. actinomycetecomitans is also associated with several other systemic diseases and complications, such as endocarditis and different abscesses. In addition to leukotoxin A, A. actinomycetecomitans possesses several different virulence factors, including bacteriocins, chemotaxis inhibitory factors, cytotoxic factors, Fc-binding proteins, immunosuppressive factors, lipopolysaccharide collagenase, fibroblast inhibitory factors, antibiotic resistance determinants, adhesins, invasive factors and factors that inhibit the function of polymorphonuclear leukocytes. The ability of A. actinomycetemcomitans lipopolysaccharide to induce macrophages to secrete the interleukins IL-1, IL-1β, and tumor necrosis factor (TNF) is of considerable importance. The primary etiologic factor in the pathogenesis of periodontal disease is the oral biofilm colonized by anaerobic bacteria. Among these, A. actinomycetemcomitans occupies an important place as a facultative anaerobic bacterium. In addition, A. actinomycetemcomitans possesses many virulence factors that contribute to its potential to cause cancer. This article provides an overview of the virulence factors of A. actinomycetecomitans and its association with various systemic diseases, its oncogenic potential, and the treatment options for infections caused by A. actinomycetecomitans. [ABSTRACT FROM AUTHOR]

Introduction Aggregatibacter (Actinobacillus) actinomycetemcomitans is a commensal bacterial pathogen in the human oral cavity. It can, however, represent the source of local or systemic infections with serious evolution, in particular infective endocarditis. We present a particular case of an adult male patient with infective endocarditis with A. actinomycetemcomitans and patent ductus arteriosus (PDA). Case report A 37-year-old patient, chronic ethanol user, is hospitalized for altered general condition, persistent cough, left chest pain, headache and dizziness, symptoms evolving for about 3 weeks. The clinical examination revealed crackling pulmonary rales present basally bilaterally, as well as numerous cavities and dental abscesses. Chest radiography showed mixed left hiliobasal pneumonia. Chest CT depicted pulmonary abscess and two filling defects in the pulmonary artery trunk, possible thrombotic/vegetative images/mediastinal thrombotic/adenopathic images. Broad spectrum antibiotic treatment was initiated. Transthoracic ultrasonography visualized persistence of ductus arteriosus and an echodense formation attached to the lateral wall of the pulmonary artery trunk. Following positive blood cultures for Aggregatibacter actinomycetemcomitans, the diagnosis of infective endocarditis was established and antibiotic treatment was de-escalated to ceftriaxone according to the antibiogram. The clinical course under treatment was slowly favorable, the patient was discharged on request on day 44 with continued treatment at home. Conclusions Infective endocarditis caused by Aggregatibacter actinomycetemcomitans should be considered in patients with altered general condition and congenital cardiovascular defects. In the present case, the patient presented two risk factors, namely poor dental hygiene and PDA. [ABSTRACT FROM AUTHOR]

Aggregatibacter actinomycetemcomitans is an opportunistic Gram-negative periodontopathogen strongly associated with periodontitis and infective endocarditis. Recent evidence suggests that periodontopathogens can influence the initiation and progression of oral squamous cell carcinoma (OSCC). Herein we aimed to investigate the effect of A. actinomycetemcomitans-derived extracellular vesicles (EVs) on OSCC cell behavior compared with EVs from periodontopathogens known to associate with carcinogenesis. EVs were isolated from: A. actinomycetemcomitans and its mutant strains lacking the cytolethal distending toxin (CDT) or lipopolysaccharide (LPS) O-antigen; Porphyromonas gingivalis; Fusobacterium nucleatum; and Parvimonas micra. The effect of EVs on primary and metastatic OSCC cells was assessed using cell proliferation, apoptosis, migration, invasion, and tubulogenesis assays. A. actinomycetemcomitans-derived EVs reduced the metastatic cancer cell proliferation, invasion, tubulogenesis, and increased apoptosis, mostly in CDT- and LPS O-antigen-dependent manner. EVs from F. nucleatum impaired the metastatic cancer cell proliferation and induced the apoptosis rates in all OSCC cell lines. EVs enhanced cancer cell migration regardless of bacterial species. In sum, this is the first study demonstrating the influence of A. actinomycetemcomitans-derived EVs on oral cancer in comparison with other periodontopathogens. Our findings revealed a potential antitumorigenic effect of these EVs on metastatic OSCC cells, which warrants further in vivo investigations. [ABSTRACT FROM AUTHOR]

Background: This study determined the prevalence of aggressive (molar‐incisor pattern) (Ag/MI) periodontitis and assessed the associated subgingival bacterial‐herpesvirus microbiota in Pueblo Indian adolescents in the southwestern United States. Methods: The study included 240 Pueblo Indian adolescents, aged 13–20 years old, residing in three Rio Grande River villages in New Mexico and the Hopi Pueblo reservation in Arizona. Adolescents with Ag/MI periodontitis or periodontal health provided subgingival samples for culture of bacterial pathogens and for polymerase chain reaction detection of periodontal herpesviruses. Results: Ag/MI periodontitis was detected in 22 (9.2%) Pueblo Indian adolescents, with 21 exhibiting a localized molar‐incisor breakdown pattern. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and other red/orange complex bacterial pathogens predominated in Ag/MI periodontitis, whereas periodontal health yielded mainly viridans streptococci and Actinomyces species. Periodontal herpesviruses demonstrated a 3.5 odds ratio relationship with Ag/MI periodontitis. The only adolescent with generalized Ag/MI periodontitis harbored viral co‐infection by cytomegalovirus plus Epstein–Barr virus Type 1, in addition to A. actinomycetemcomitans, P. gingivalis, and several other periodontopathic bacteria. Conclusions: Pueblo Indian adolescents showed an unusually high prevalence of early‐age Ag/MI periodontitis predominated by periodontopathic bacteria and herpesviruses suspected to be major etiologic agents of the disease. [ABSTRACT FROM AUTHOR]

Introduction: Antiseptic agents used in periodontics as anti-plaque and anti-gingivitis agents are primarily chemical substances such as Bis-biguanide derivatives (chlorhexidine) or essential oils. Herbal derivatives have gained prominence in the recent past due to their activity against putative periodontal pathogens; however, only a few have achieved commercialisation. This study focusses on determining the efficacy of an extract from a widely available herb, Indian mint-Plectranthus Amboinicus Methanolic extract (PAM), which has known anti-microbial and anti-inflammatory properties against periodontal pathogens in-vitro. Aim: To assess the Minimum Inhibitory Concentration (MIC) and anti-biofilm property of PAM solvent extract against pure strains of putative periodontal pathogens, namely Porphyromonas gingivalis (American Type Culture Collection-ATCC 33277), Fusobacterium nucleatum (ATCC 25586), and Aggregatibacter actinomycetemcomitans (ATCC 43718). Materials and Methods: The extract of PA was prepared using methanol and a Soxhlet extractor. An in-vitro analysis of the MIC and anti-biofilm efficacy of the extract was performed against standard strains of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum using the broth dilution method and microtitre-crystal violet assay, respectively. The MIC activity of the PAM extracts was compared with Chlorhexidine as a standard. Results: The MIC value of P. amboinicus extract was nearly similar to Chlorhexidine as assessed by the broth dilution method. The MIC of P. amboinicus extract for A.a and P.g was 0.4 ug/mL, F.n was 0.8 ug/mL, and the Chlorhexidine values against all three periodontal pathogens were 0.2 ug/mL. The anti-biofilm activity of The extract of PAMwas evaluated using the microtitre-crystal violet assay, and the Optical Density (OD) values were reduced after exposure to the extract, with a significant reduction (p

Background: The Korean name for Angelica gigas Nakai (AGN) is Cham-dang-gui, which grows naturally or is cultivated, and its dried roots are used in traditional herbal medicines. The AGN root exert various pharmacological effects. Despite the various pharmacological effects of the AGN root, there are no reports on its anti-oral microbial effects. The purpose of this study was to reveal the anti-oral microbial effect and the microbial and biochemical changes in oral microorganisms according to the concentration of the ethanol extract of AGN (EAGN) root, and to confirm the possibility of using EAGN as a plant-derived functional substance for controlling oral infectious microorganisms.Methods: Disk diffusion test, growth measurement, biofilm formation assay, and measurements of acid production and buffering capacity were performed to confirm the antibacterial effect of EAGN. Results: EAGN showed anti-oral bacterial effects against Streptococcus mutans and Aggregatibacter actinomycetemcomitans at all concentrations, with S. mutans showing a more susceptible effect at concentrations above 5.0 mg/ml and A. actinomycetemcomitans at 3.75 mg/ml. EAGN treatment significantly reduced A. actinomycetemcomitans growth at all concentrations tested. Biofilm formation was significantly reduced at concentrations above 3.75 mg/ml for S. mutans and 2.5 mg/ml for A. actinomycetemcomitans. Acid production in S. mutans and A. actinomycetemcomitans was significantly increased by treatment with EAGN, and the buffering capacities of S. mutans and A. actinomycetemcomitans increased from an EAGN concentration of 3.75 mg/ml and above. Conclusion: EAGN showed anti-oral bacterial effects against both S. mutans and A. actinomycetemcomitans at concentrations above 3.75 mg/ml, which were thought to be related to the inhibition of their growth and biofilm formation. Therefore, EAGN can be used as a safe functional substance derived from medicinal plants owing to its antibacterial effects against S. mutans and A. actinomycetemcomitans.

SCIENTIFIC RELEVANCE. The incidence of periodontal infections with antibiotic-resistant strains of Actinomyces oris and Aggregatibacter actinomycetemcomitans capable of forming biofilms in the oral cavity is increasing, and the effectiveness of antimicrobials against biofilms is insufficient. Therefore, the isolation of bacteriophages active against A. oris and Ag. actinomycetemcomitans is an urgent task.AIM. This study aimed to isolate bacteriophages active against A. oris and Ag. actinomycetemcomitans, study their biological properties, and select optimum culture conditions providing pure lines and high titres of bacteriophages.MATERIALS AND METHODS. Bacteriophages were isolated from biosamples of saliva, dental plaque, and periodontal pocket contents. The study determined bacteriophage characteristics, including the optimum multiplicity of infection, phage–cell system cultivation time, resistance to various temperatures and pH, and storage stability. Bacteriophage morphology was studied using transmission electron microscopy. Negative colony morphology, lytic activity, host range, and specificity were assessed using spot testing and the Gratia method. Bacterial strains were obtained from the strain collection of the Micromir research and production centre.RESULTS. The authors isolated and studied 3 novel bacteriophages active against A. oris (vB_AorP_1/G-12, vB_AorP_2/Ch-28, and vB_AorP_3/Bl-35) and 1 bacteriophage active against Ag. actinomycetemcomitans (vB_AacS_1/Dc-1). The A. oris bacteriophages were classified as podoviruses, and the vB_AacS_1/Dc-1 bacteriophage was classified as a siphovirus. The phages formed completely transparent round plaques without a halo, with a diameter ranging from 0.8±0.1 to 4.0±0.2 mm. The optimum parameters established to obtain pure phages with maximum titres included a multiplicity of infection of 0,1–10 and phage–cell system cultivation time of 8–12 hours. The study demonstrated the ability of A. oris bacteriophages to lyse Actinomyces naeslundii strains. Of the 15 A. oris bacteriophage strains studied, vB_AorP_1/G-12, vB_AorP_2/Ch-28, and vB_AorP_3/Bl-35 lysed 10, 8, and 12 bacterial strains, respectively. The vB_AacS_1/Dc-1 phage isolate exhibited lytic activity against both tested strains of Ag. actinomycetemcomitans. The studied phages demonstrated stability under abiotic stress and long-term storage conditions.CONCLUSIONS. The authors isolated 3 novel bacteriophages active against A. oris and 1 bacteriophage active against Ag. actinomycetemcomitans and studied their biological properties. The isolated bacteriophages are promising as candidates for further research using clinical strains and whole-genome sequencing.

Aims The current study aimed to explore the adjuvant therapeutic effect of N-acyl homoserine lactones (AHLs)-lactonase est816 on Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) biological behaviors and periodontitis progression.Methods The inhibitory properties of est816 were detected by live/dead bacterial staining, scanning electron microscope (SEM), crystal-violet staining and reverse-transcription quantitative PCR (RT-qPCR). Biocompatibility of est816 on human gingival fibroblasts (HGFs) and human gingival epithelial cells (HGEs) was evaluated by CCK8 and ELISA. The ligature-induced periodontitis model was established in rats. Micro computed tomography and immunohistochemical and histological staining served to evaluate the effect of est816 on the prevention of periodontitis in vivo.Results est816 significantly attenuated biofilm formation, reduced the mRNA expression of cytolethal distending toxin, leukotoxin and poly-N-acetyl glucosamine (PNAG) and downregulated expressions of interleukin-6 and tumor necrosis factor-α with low cell toxicity. In vivo investigations revealed est816 decreased alveolar bone resorption, suppressed matrix metalloproteinase-9 expression and increased osteoprotegerin expression.Conclusion est816 inhibited A. actinomycetemcomitans biofilm formation and virulence release, resulting in anti-inflammation and soothing of periodontitis in rats, indicating that est816 could be investigated in further research on periodontal diseases.

Introduction: Quorum-quenching enzyme Est816 hydrolyzes the lactone rings of N-acyl homoserine lactones, effectively blocking the biofilm formation and development of Gram-negative bacteria. However, its applications in the oral field is limited. This study aimed to evaluate the efficacy of enzyme Est816 in combination with antibiotics against periodontitis induced by Aggregatibacter actinomycetemcomitans in vitro and in vivo. Methods: The antimicrobial efficacy of enzyme Est816 in combination with minocycline, metronidazole, and amoxicillin was determined using the minimum inhibitory concentration test. The anti-biofilm effect of enzyme Est816 was assessed using scanning electron microscopy, live/dead bacterial staining, crystal violet staining, and real-time quantitative PCR. Biocompatibility of enzyme Est816 was assessed in human gingival fibroblasts (HGF) by staining. A rat model of periodontitis was established to evaluate the effect of enzyme Est816 combined with minocycline using micro-computed tomography and histological staining. Results: Compared to minocycline, metronidazole, and amoxicillin treatment alone, simultaneous treatment with enzyme Est816 increased the sensitivity of biofilm bacteria to antibiotics. Enzyme Est816 with minocycline exhibited the highest rate of biofilm clearance and high biocompatibility. Moreover, the combination of enzyme Est816 with antibiotics improved the antibiofilm effects of the antibiotics synergistically, reducing the expression of the virulence factor leukotoxin gene (ltxA) and fimbria-associated gene (rcpA). Likewise, the combination of enzyme Est816 with minocycline exhibited a remarkable inhibitory effect on bone resorption and inflammation damage in a rat model of periodontitis. Discussion: The combination of enzyme Est816 with antibiotics represents a prospective anti-biofilm strategy with the potential to treat periodontitis. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Aggregatibacter spp. is a rare cause for cardiac device infections. Due to limited data, the management of Aggregatibacter spp. device infections is not clearly defined but should always involve device removal and prolonged intravenous antibiotics. [ABSTRACT FROM AUTHOR]

Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) is capable of intoxicating lymphocytes macrophages, mast cells and epithelial cells. Following Cdt binding to cholesterol, in the region of membrane lipid rafts, the CdtB and CdtC subunits are internalized and traffic to intracellular compartments. These events are dependent upon, cellugyrin, a critical component of synaptic like microvesicles (SLMVCg+). Target cells, such as Jurkat cells, rendered unable to express cellugyrin are resistant to Cdt-induced toxicity. Similar to Cdt, SARS-CoV-2 entry into host cells is initiated by binding to cell surface receptors, ACE-2, also associated with cholesterol-rich lipid rafts; this association leads to fusion and/or endocytosis of viral and host cell membranes and intracellular trafficking. The similarity in internalization pathways for both Cdt and SARS-CoV-2 led us to consider the possibility that cellugyrin was a critical component in both processes. Cellugyrin deficient Calu-3 cells (Calu-3Cg-) were prepared using Lentiviral particles containing shRNA; these cells were resistant to infection by VSV/SARS-CoV-2-spike pseudotype virus and partially resistant to VSV/VSV-G pseudotype virus. Synthetic peptides representing various regions of the cellugyrin protein were prepared and assessed for their ability to bind to Cdt subunits using surface plasmon resonance. Cdt was capable of binding to a region designated the middle outer loop (MOL) which corresponds to a region extending into the cytoplasmic surface of the SLMVCg+. SARS-CoV-2 spike proteins were assessed for their ability to bind to cellugyrin peptides; SARS-CoV-2 full length spike protein preferentially binds to a region within the SLMVCg+ lumen, designated intraluminal loop 1A. SARS-CoV-2-spike protein domain S1, which contains the receptor binding domains, binds to cellugyrin N-terminus which extends out from the cytoplasmic surface of SLMV. Binding specificity was further analyzed using cellugyrin scrambled peptide mutants. We propose that SLMVCg+ represent a component of a common pathway that facilitates pathogen and/or pathogen-derived toxins to gain host cell entry. [ABSTRACT FROM AUTHOR]

Microbes frequently experience nutrient deprivations in the natural environment and may enter dormancy. Aggregatibacter actinomycetemcomitans is known to establish long-term infections in humans. This study examined the dormancy-like phenotype of an A. actinomycetemcomitans strain D7S-1 and its isogenic smooth-colony mutant D7SS. A tissue culture medium RPMI-1640 was nutrient-deficient (ND) and unable to support A. actinomycetemcomitans growth. RPMI-1640 amended with bases was nutrient-limited (NL) and supported limited growth of A. actinomycetemcomitans less than the nutrient-enriched (NE) laboratory medium did. Strain D7S-1, after an initial 2-log reduction in viability, maintained viability from day 4 to day 15 in the NL medium. Strain D7SS, after 1-log reduction in viability, maintained viability from day 3 to day 5. In contrast, bacteria in the NE medium were either non-recoverable (D7S-1; >6-log reduction) or continued to lose viability (D7SS; 3-log reduction) on day 5 and beyond. Scanning and transmission electron microscopy showed that A. actinomycetemcomitans in the NL medium formed robust biofilms similar to those in the NE medium but with evidence of stress. A. actinomycetemcomitans in the ND medium revealed scant biofilms and extensive cellular damage. We concluded that A. actinomycetemcomitans grown in the NL medium exhibited a dormancy-like phenotype characterized by minimum growth, prolonged viability, and distinct cellular morphology. [ABSTRACT FROM AUTHOR]

The presence of periodontal pathogens is associated with an increased prevalence of rheumatoid arthritis (RA). The systemic antibody response to epitopes of these bacteria is often used as a proxy to study correlations between bacteria and RA. The primary aim of the present study is to examine the correlation between the presence of Aggregatibacter actinomycetemcomitans (Aa) in the oral cavity and serum antibodies against the leukotoxin (LtxA) produced by this bacterium. The salivary presence of Aa was analyzed with quantitative PCR and serum LtxA ab in a cell culture-based neutralization assay. The analyses were performed on samples from a well-characterized RA cohort (n = 189) and a reference population of blood donors (n = 101). Salivary Aa was present in 15% of the RA patients and 6% of the blood donors. LtxA ab were detected in 19% of RA-sera and in 16% of sera from blood donors. The correlation between salivary Aa and serum LtxA ab was surprisingly low (rho = 0.55 [95% CI: 0.40, 0.68]). The presence of salivary Aa showed no significant association with any of the RA-associated parameters documented in the cohort. A limitation of the present study is the relatively low number of individuals with detectable concentrations of Aa in saliva. Moreover, in the comparison of detectable Aa prevalence between RA patients and blood donors, we assumed that the two groups were equivalent in other Aa prognostic factors. These limitations must be taken into consideration when the result from the study is interpreted. We conclude that a systemic immune response to Aa LtxA does not fully reflect the prevalence of Aa in saliva. In addition, the association between RA-associated parameters and the presence of Aa was negligible in the present RA cohort. [ABSTRACT FROM AUTHOR]

The Gram-positive bacterium, Filifactor alocis is an oral pathogen, and approximately 50% of known strains encode a recently identified repeat-in-toxin (RTX) protein, FtxA. By assessing a longitudinal Ghanaian study population of adolescents (10-19 years of age; mean age 13.2 years), we recently discovered a possible correlation between deep periodontal pockets measured at the two-year follow-up, presence of the ftxA gene, and a high quantity of F. alocis. To further understand the contribution of F. alocis and FtxA in periodontal disease, we used qPCR in the present study to assess the carriage loads of F. alocis and the prevalence of its ftxA gene in subgingival plaque specimens, sampled at baseline from the Ghanaian cohort (n=500). Comparing these results with the recorded clinical attachment loss (CAL) longitudinal progression data from the two-year follow up, we concluded that carriers of ftxA-positive F. alocis typically exhibited higher loads of the bacterium. Moreover, high carriage loads of F. alocis and concomitant presence of the ftxA gene were two factors that were both associated with an enhanced prevalence of CAL progression. Interestingly, CAL progression appeared to be further promoted upon the simultaneous presence of F. alocis and the non-JP2 genotype of Aggregatibacter actinomycetemcomitans. Taken together, our present findings are consistent with the notion that F. alocis and its ftxA gene promotes CAL during periodontal disease. [ABSTRACT FROM AUTHOR]

Introduction: Antiseptic agents used in periodontics as anti-plaque and anti-gingivitis agents are primarily chemical substances such as Bis-biguanide derivatives (chlorhexidine) or essential oils. Herbal derivatives have gained prominence in the recent past due to their activity against putative periodontal pathogens; however, only a few have achieved commercialisation. This study focusses on determining the efficacy of an extract from a widely available herb, Indian mint-Plectranthus Amboinicus Methanolic extract (PAM), which has known anti-microbial and anti-inflammatory properties against periodontal pathogens in-vitro. Aim: To assess the Minimum Inhibitory Concentration (MIC) and anti-biofilm property of PAM solvent extract against pure strains of putative periodontal pathogens, namely Porphyromonas gingivalis (American Type Culture Collection-ATCC 33277), Fusobacterium nucleatum (ATCC 25586), and Aggregatibacter actinomycetemcomitans (ATCC 43718). Materials and Methods: The extract of PA was prepared using methanol and a Soxhlet extractor. An in-vitro analysis of the MIC and anti-biofilm efficacy of the extract was performed against standard strains of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum using the broth dilution method and microtitre-crystal violet assay, respectively. The MIC activity of the PAM extracts was compared with Chlorhexidine as a standard. Results: The MIC value of P. amboinicus extract was nearly similar to Chlorhexidine as assessed by the broth dilution method. The MIC of P. amboinicus extract for A.a and P.g was 0.4 ug/mL, F.n was 0.8 ug/mL, and the Chlorhexidine values against all three periodontal pathogens were 0.2 ug/mL. The anti-biofilm activity of The extract of PAMwas evaluated using the microtitrecrystal violet assay, and the Optical Density (OD) values were reduced after exposure to the extract, with a significant reduction (p<0.001) of the biofilm-forming bacteria observed. Conclusion: The methanol extract of PAM demonstrated a noteworthy MIC, exhibiting effectiveness at a low concentration of 0.4 µg/mL against Aggregatibacter actinomycetemcomitans in three repeated trials. Moreover, this extract displayed significant inhibitory effects on the biofilm formation of periodontal pathogens Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum (Pg, Aa, Fn), suggesting its potential as an alternative to conventional chemical anti-microbials. [ABSTRACT FROM AUTHOR]

Peri-implantitis (PI), the most widespread condition in the oral cavity, affects patients globally; thus, advanced research in both in vitro and in vivo studies is required. This study aimed to develop peri-implantitis in the rat model by oral contamination with bacteria responsible for PI in humans. The study was carried out in three stages: the extraction of the maxillary first molar to reproduce the human edentation, the mounting of the implant, and finally, the contamination of the device by gavage with Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus oralis. The hematological examinations showed statistically significant increases for WBCs (white blood cells), Hb (hemoglobin), RBCs (red blood cells), MCH (mean corpuscular hemoglobin), MCHC (mean corpuscular hemoglobin concentration), and PLTs (platelets), but especially for the level of neutrophils and lymphocytes, and the systemic immunoinflammatory index completed the picture related to the inflammatory response triggered as a result of the activity of microorganisms pathogens on oral tissues. By examining the liver and kidney profile, we hypothesized that peri-implantitis is associated with systemic diseases, and the histopathological examination showed peri-implantitis lesions characterized by a marked inflammatory infiltrate with numerous neutrophils and lymphocytes. By corroborating all the results, we successfully developed a rat peri-implantitis model using a mixed bacterial infection through the oral gavage technique. [ABSTRACT FROM AUTHOR]

The benefits of probiotics on dysbiotic microbiomes and inflammation are dependent on the tested strain, host factors, and the resident microbiome. There is limited knowledge on the effects of probiotics in A. actinomycetemcomitans-associated periodontitis. Thus, Lactobacillus acidophilus LA5 (LA5) was orally inoculated for 30 days in C57Bl/6 mice infected with A. actinomycetemcomitans JP2 (Aa) and S. gordonii (Sg). Alveolar bone loss, gingival gene expression, and oral and gut microbiomes were determined. LA5 controlled bone loss in Aa+Sg-infected mice, downregulated the expression of Il-1β and upregulated Il-10 in gingival tissues, and altered the oral and gut microbiomes. LA5 increased the diversity of the oral microbiome of Aa+Sg infected mice, and Aa+Sg and Aa+Sg+LA5 oral or gut microbiomes clustered apart. LA5 induced shifts in Aa+Sg infected mice by increasing the abundance of Muribaculaceae and decreasing Bifidobacteriaceae in the oral cavity and increasing the abundance of Verrucomicrobiae and Eggerthellales in the gut. In conclusion, LA5 oral administration controls experimental Aa-associated periodontitis by altering inflammatory gene expression and the oral and gut microbiomes. [ABSTRACT FROM AUTHOR]

Aggregatibacter actinomycetemcomitans is a Gram-negative bacterium associated with localized aggressive periodontitis as well as some systemic diseases. The strains of A. actinomycetemcomitans most closely associated with disease produce more of a secreted leukotoxin (LtxA) than isolates from healthy carriers, suggesting a key role for this toxin in disease progression. LtxA is released into the bacterial cytosol in a free form as well as in association with the surface of outer membrane vesicles (OMVs). We previously observed that the highly leukotoxic A. actinomycetemcomitans strain JP2 produces two populations of OMVs: a highly abundant population of small (<100 nm) OMVs and a less abundant population of large (>300 nm) OMVs. Here, we have developed a protocol to isolate the OMVs produced during each specific phase of growth and used this to demonstrate that small OMVs are produced throughout growth and lack LtxA, while large OMVs are produced only during the exponential phase and are enriched with LtxA. Our results indicate that surface-associated DNA drives the selective sorting of LtxA into large OMVs. This study provides valuable insights into the observed heterogeneity of A. actinomycetemcomitans vesicles and emphasizes the importance of understanding these variations in the context of bacterial pathogenesis. [ABSTRACT FROM AUTHOR]

Abstract Background Periodontitis is a microbially induced disease destroying structures anchoring teeth to jaw bones. Although metronidazole in combination with spiramycin is the effective conventional treatment of stage III grade C periodontitis, it has several systemic side effects. Laser therapy is widely used nowadays as an adjunct to scaling and root planing (SRP) to modulate inflammatory host response and eradicate microbes, due to bactericidal and detoxifying effects. Since microbiological analysis is one of the diagnostic methods identifying periodontal risk; our research aimed to investigate the efficacy of intra-pocket application of diode laser (980 nm) versus antibiotic therapy in enhancing clinical and microbiological parameters in stage III grade C periodontitis. Methods A randomized controlled clinical trial was conducted on fifty patients with stage III grade C periodontitis, divided equally into two groups. We managed test group by SRP with intra-pocket application of diode laser (980 nm) and the control group by SRP with systemic antibiotic administration (spiramycin and metronidazole). Then, we measured periodontal pocket depth (PPD) and clinical attachment loss (CAL) for both groups, before treatment (baseline), four and twelve weeks after. Moreover, we collected gingival crevicular fluid from both groups at baseline, four and twelve weeks after treatment and analyzed by real-time polymerase chain reaction to detect the relative count of Aggregatibacter actinomycetemcomitans and Porhyromonas gingivalis. Results Compared to baseline, all assessed clinical and microbiological parameters attested improvement at the end of the study period in each group individually with no significant difference between the two studied groups. Although, at twelve weeks, flare up of bacterial levels was detected with systemic antibiotic administration. Conclusion Laser therapy can be considered as an effective treatment modality in stage III grade C periodontitis, avoiding the systemic antibiotic side effects and solving the recurrence problems due to bacterial resistance by long term usage. Trial registration NCT05222737 retrospectively on 03/02/2022, Clinicaltrial.gov.

ABSTRACT: Objective: The aim of this work was to explore the association between Aggregatibacter actinomycetemcomitans (A actinomycetemcomitans) infection and disease activity amongst those with rheumatoid arthritis (RA) with or without periodontitis (PD) in a Chinese population. Methods: A case-control study was conducted from November 2017 to March 2019. The correlation coefficients between A actinomycetemcomitans positivity and RA-related examination indicators as well as periodontal examination parameters were calculated by using the Spearman correlation analysis. Results: A total of 115 patients with RA were recruited: 67 patients with RA only and 48 with RA + PD. The percentage of A actinomycetemcomitans positivity was significantly higher in the RA + PD group compared with the RA-only group (P = .007 for positive percentage; P = .020 for percentage of A actinomycetemcomitans positivity in the total oral microbiome). Furthermore, RA-related measures such as Disease Activity Score 28, rheumatoid factor, anticyclic citrullinated peptide, and anticitrullinated protein antibodies were all positively correlated with the percentage of A actinomycetemcomitans positivity (P range: .002∼.041). In addition, significant correlations were observed amongst A actinomycetemcomitans positivity and probing pocket depth (P = .027) and gingival index (P = .043), whereas null correlations were found amongst the percentage of A actinomycetemcomitans positivity and plaque index (P = .344), clinical attachment loss (P = .217), and bleeding on probing (P = .710). Conclusions: A actinomycetemcomitans infection may be related to the development of PD amongst patients with RA.

Abstract Aims The oral microbiota composition of patients diagnosed with Papillon-Lefèvre-syndrome and treated for several years were compared to those existing in the oral cavity of the clinically healthy family members and a cohort of patients having various stages of chronic periodontitis. Materials and methods A family with two sisters affected with severe periodontitis and with the typical skin symptoms of Papillon-Lefèvre-syndrome, and symptomless parents and third sibling were investigated. The Patients received periodontal treatment for several years and their oral microbiome was analysed by amplicon sequencing. Data were evaluated by microbial cluster analysis. Results The microbiome of the patients with Papillon-Lefèvre-syndrome was predominated with Aggregatibacter actinomycetemcomitans and associated oral periodontopathogens. Although the clinically healthy family members showed no oral disorder, their microbiome resembled that of subjects having mild periodontitis. Conclusions Predominance of A. actinomycetemcomitans in the subgingival microbiome of patients with Papillon-Lefèvre-syndrome suggests that specific treatment strategies directed against this pathobiont may improve the oral health status of the affected individuals. Trial registration The study was conducted in accordance with the Declaration of Helsinki and the ethical permission has been issued by the Human Investigation Review Board of the University of Szeged, Albert Szent-Györgyi Clinical Centre (Permission No. 63/2017-SZTE). September 19, 2017. https://u-szeged.hu/klinikaikutatas/rkeb-altal-jovahagyott/rkeb-2017 .

Aim: The main purpose of the present study was to investigate the carrier rate of Aggregatibacter actinomycetemcomitans and its JP2 genotype in a cohort of 200 Western Australians diagnosed with periodontitis. Materials and Methods: In this descriptive cross-sectional study, 220 consecutive patients with periodontitis, aged 18 years and older, were recruited to a specialist periodontal practice in Perth City. Every patient included in this study contributed three different intra-oral samples. Periodontal, radiographical, and microbiological assessments were performed. The samples were analysed using a polymerase chain reaction for the detection of Aggregatibacter actinomycetemcomitans and its JP2 genotype using the primers and conditions described previously. A Chi-square test and logistic regression analysis were performed to evaluate the results. Results: The prevalence of Aggregatibacter actinomycetemcomitans was 28.18%. The carrier rates of A. actinomycetemcomitans in the unstimulated saliva, cheek swabs, and pooled subgingival plaque samples were 21.80%, 19.50%, and 17.70%, respectively. There was a significant correlation between the severe form of periodontitis (stage IV, grade C) and younger age (p = 0.004), positive family history of periodontitis (p < 0.001), oral hygiene method (p < 0.001), and irregular dental visit attendance (p < 0.001). The binary logistic regression analysis revealed that having severe periodontitis risk increased almost three times in those who were young (OR: 2.812) and came from a family with a history of periodontal disease (OR: 3.194). However, the risk of severe periodontitis was five times higher in those patients with tooth loss due to periodontal disease (OR: 5.071). The highly leukotoxic JP2 genotype of Aggregatibacter actinomycetemcomitans was not detected. Conclusions: This study of a Western Australian cohort confirmed the low presence of Aggregatibacter actinomycetemcomitans and the complete absence of its JP2 genotype. Young age, family history of periodontal disease, lack of flossing, irregular dental visits, and tooth loss due to periodontitis were identified as potential risk factors for periodontitis stage IV, grade C in this cohort.

Aggregatibacter actinomycetemcomitans ApiA is a trimeric autotransporter outer membrane protein (Omp) that participates in multiple functions, enabling A. actinomycetemcomitans to adapt to a variety of environments. The goal of this study is to identify regions in the apiA gene responsible for three of these functions: auto-aggregation, buccal epithelial cell binding, and complement resistance. Initially, apiA was expressed in Escherichia coli. Finally, wild-type A. actinomycetemcomitans and an apiA-deleted version were tested for their expression in the presence and absence of serum and genes related to stress adaptation, such as oxygen regulation, catalase activity, and Omp proteins. Sequential deletions in specific regions in the apiA gene as expressed in E. coli were examined for membrane proteins, which were confirmed by microscopy. The functional activity of epithelial cell binding, auto-aggregation, and complement resistance were then assessed, and regions in the apiA gene responsible for these functions were identified. A region spanning amino acids 186–217, when deleted, abrogated complement resistance and Factor H (FH) binding, while a region spanning amino acids 28–33 was related to epithelial cell binding. A 13-amino-acid peptide responsible for FH binding was shown to promote serum resistance. An apiA deletion in a clinical isolate (IDH781) was created and tested in the presence and/or absence of active and inactive serum and genes deemed responsible for prominent functional activity related to A. actinomycetemcomitans survival using qRT-PCR. These experiments suggested that apiA expression in IDH781 is involved in global regulatory mechanisms that are serum-dependent and show complement resistance. This is the first study to identify specific apiA regions in A. actinomycetemcomitans responsible for FH binding, complement resistance, and other stress-related functions. Moreover, the role of apiA in overall gene regulation was observed.

The periodontal disease pathobiont Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) may exert a range of detrimental effects on periodontal diseases in general and, more specifically, with the initiation and progression of Localized Stage III Grade C periodontitis (molar–incisor pattern). In this review of the biogeography of this pathobiont, the full range of geographical scales for A. actinomycetemcomitans, from global origins and transmission to local geographical regions, to more locally exposed probands and families, to the individual host, down to the oral cavity, and finally, to spatial interactions with other commensals and pathobionts within the plaque biofilms at the micron/nanoscale, are reviewed. Using the newest technologies in genetics, imaging, in vitro cultures, and other research disciplines, investigators may be able to gain new insights to the role of this pathobiont in the unique initial destructive patterns of Localized Stage III Grade C periodontitis. These findings may incorporate the unique features of the microbiome that are influenced by variations in the geographic environment within the entire mouth. Additional insights into the geographic distribution of molar–incisor periodontal breakdown for Localized Stage III Grade C periodontitis may derive from the spatial interactions between A. actinomycetemcomitans and other pathobionts such as Porphyromonas gingivalis, Filifactor aclocis, and commensals such as Streptococcus gordonii. In addition, while the association of A. actinomycetemcomitans in systemic diseases is limited at the present time, future studies into possible periodontal disease–systemic disease links may also find A. actinomycetemcomitans and its geographical interactions with other microbiome members to provide important clues as to implications of pathobiological communications.

This review addresses the recent World Workshop Consensus Conference (WWCC) decision to eliminate Localized Aggressive Periodontitis (LAgP) in young adults as a distinct form of periodontitis. A “Consensus” implies widespread, if not unanimous, agreement among participants. However, a significant number of attendees were opposed to the elimination of the LAgP classification. The substantial evidence supporting a unique diagnosis for LAgP includes the (1) incisor/molar pattern of disease, (2) young age of onset, (3) rapid progression of attachment and bone loss, (4) familial aggregation across multiple generations, and (5) defined consortium of microbiological risk factors including Aggregatibacter actinomycetemcomitans. Distinctive clinical signs and symptoms of LAgP are presented, and the microbial subgingival consortia that precede the onset of signs and symptoms are described. Using Bradford–Hill guidelines to assess causation, well-defined longitudinal studies support the unique microbial consortia, including A. actinomycetemcomitans as causative for LAgP. To determine the effects of the WWCC elimination of LAgP on research, we searched three publication databases and discovered a clear decrease in the number of new publications addressing LAgP since the new WWCC classification. The negative effects of the WWCC guidelines on both diagnosis and treatment success are presented. For example, due to the localized nature of LAgP, the practice of averaging mean pocket depth reduction or attachment gain across all teeth masks major changes in disease recovery at high-risk tooth sites. Reinstating LAgP as a distinct disease entity is proposed, and an alternative or additional way of measuring treatment success is recommended based on an assessment of the extension of the time to relapse of subgingival re-infection. The consequences of the translocation of oral microbes to distant anatomical sites due to ignoring relapse frequency are also discussed. Additional questions and future directions are also presented.

Background: Periodontitis is a microbially induced disease destroying structures anchoring teeth to jaw bones. Although metronidazole in combination with spiramycin is the effective conventional treatment of stage III grade C periodontitis, it has several systemic side effects. Laser therapy is widely used nowadays as an adjunct to scaling and root planing (SRP) to modulate inflammatory host response and eradicate microbes, due to bactericidal and detoxifying effects. Since microbiological analysis is one of the diagnostic methods identifying periodontal risk; our research aimed to investigate the efficacy of intra-pocket application of diode laser (980 nm) versus antibiotic therapy in enhancing clinical and microbiological parameters in stage III grade C periodontitis. Methods: A randomized controlled clinical trial was conducted on fifty patients with stage III grade C periodontitis, divided equally into two groups. We managed test group by SRP with intra-pocket application of diode laser (980 nm) and the control group by SRP with systemic antibiotic administration (spiramycin and metronidazole). Then, we measured periodontal pocket depth (PPD) and clinical attachment loss (CAL) for both groups, before treatment (baseline), four and twelve weeks after. Moreover, we collected gingival crevicular fluid from both groups at baseline, four and twelve weeks after treatment and analyzed by real-time polymerase chain reaction to detect the relative count of Aggregatibacter actinomycetemcomitans and Porhyromonas gingivalis. Results: Compared to baseline, all assessed clinical and microbiological parameters attested improvement at the end of the study period in each group individually with no significant difference between the two studied groups. Although, at twelve weeks, flare up of bacterial levels was detected with systemic antibiotic administration. Conclusion: Laser therapy can be considered as an effective treatment modality in stage III grade C periodontitis, avoiding the systemic antibiotic side effects and solving the recurrence problems due to bacterial resistance by long term usage. Trial registration: NCT05222737 retrospectively on 03/02/2022, Clinicaltrial.gov. [ABSTRACT FROM AUTHOR]

Recently, we reported that oral-epithelial cells (OE) are unique in their response to Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) in that cell cycle arrest (G2/M) occurs without leading to apoptosis. We now demonstrate that Cdt-induced cell cycle arrest in OE has a duration of at least 7 days with no change in viability. Moreover, toxin-treated OE develops a new phenotype consistent with cellular senescence; this includes increased senescence-associated β-galactosidase (SA-β-gal) activity and accumulation of the lipopigment, lipofuscin. Moreover, the cells exhibit a secretory profile associated with cellular senescence known as the senescence-associated secretory phenotype (SASP), which includes IL-6, IL-8 and RANKL. Another unique feature of Cdt-induced OE senescence is disruption of barrier function, as shown by loss of transepithelial electrical resistance and confocal microscopic assessment of primary gingival keratinocyte structure. Finally, we demonstrate that Cdt-induced senescence is dependent upon the host cell protein cellugyrin, a homologue of the synaptic vesicle protein synaptogyrin. Collectively, these observations point to a novel pathogenic outcome in oral epithelium that we propose contributes to both A. actinomycetemcomitans infection and periodontal disease progression. [ABSTRACT FROM AUTHOR]

Aims: The oral microbiota composition of patients diagnosed with Papillon-Lefèvre-syndrome and treated for several years were compared to those existing in the oral cavity of the clinically healthy family members and a cohort of patients having various stages of chronic periodontitis. Materials and methods: A family with two sisters affected with severe periodontitis and with the typical skin symptoms of Papillon-Lefèvre-syndrome, and symptomless parents and third sibling were investigated. The Patients received periodontal treatment for several years and their oral microbiome was analysed by amplicon sequencing. Data were evaluated by microbial cluster analysis. Results: The microbiome of the patients with Papillon-Lefèvre-syndrome was predominated with Aggregatibacter actinomycetemcomitans and associated oral periodontopathogens. Although the clinically healthy family members showed no oral disorder, their microbiome resembled that of subjects having mild periodontitis. Conclusions: Predominance of A. actinomycetemcomitans in the subgingival microbiome of patients with Papillon-Lefèvre-syndrome suggests that specific treatment strategies directed against this pathobiont may improve the oral health status of the affected individuals. Trial registration: The study was conducted in accordance with the Declaration of Helsinki and the ethical permission has been issued by the Human Investigation Review Board of the University of Szeged, Albert Szent-Györgyi Clinical Centre (Permission No. 63/2017-SZTE). September 19, 2017. . [ABSTRACT FROM AUTHOR]

Periodontitis is an exemplar of dysbiosis associated with the coordinated action of multiple members within the microbial consortium. The polymicrobial synergy and dysbiosis hypothesis proposes a dynamic host-microbiome balance, with certain modulators capable of disrupting eubiosis and driving shifts towards dysbiosis within the community. However, these factors remain to be explored. We established a Porphyromonas gingivalis - or Aggregatibacter actinomycetemcomitans -modified subgingival microbiome model and 16S rRNA sequencing revealed that P. gingivalis and A. actinomycetemcomitans altered the microbiome structure and composition indicated by α and β diversity metrics. P. gingivalis increased the subgingival dysbiosis index (SDI), while A. actinomycetemcomitans resulted in a lower SDI. Furthermore, P. gingivalis -stimulated microbiomes compromised epithelium function and reduced expression of tight junction proteins, whereas A. actinomycetemcomitans yielded mild effects. In conclusion, by inoculating P. gingivalis , we created dysbiotic microcosm biofilms in vitro resembling periodontitis-related subgingival microbiota, exhibiting enhanced dysbiosis and impaired epithelium integrity. [ABSTRACT FROM AUTHOR]

As a commonly-found pathogen in periodontal disease, Aggregatibacter actinomycetemcomitans has been reported with several antibiotic resistance. Thus, to develop an alternative and protective therapy for A. actinomycetemcomitans infections is urgently needed in dentistry. In this study, we sought to synthesize a silica-based material to deliver silver nanoparticles for antibacterial purposes. Also, the bioactivities were examined via analyzing the formation of hydroxyapatite. The 80S/Ag powders were prepared by the evaporation-induced self-assembly method, with Si, Ca, P, and Ag composition ratios of 80, 15, 5, and 1/5/10 (mole percentage), respectively. The nitrogen adsorption-desorption isotherms, transmission electron microscope, selected area electron diffraction, and Fourier transform infrared spectroscopy were conducted for textural analyses. The disk diffusion test was carried out against A. actinomycetemcomitans strain ATCC 29523. In vitro bioactivity assessment involved soaking 80S/Ag membrane powders in acellular simulated body fluid. We successfully developed a material consisting of Si, Ca, P, and Ag, namely the 80S/Ag. In the antibacterial testing, the 80S/Ag demonstrated antibacterial activity against the commonly-found oral pathogen, A. actinomycetemcomitans , with a long-lasting effect for 168h. The formation of hydroxyapatite in simulated body fluid highlighted the characteristic of dentine remineralization for the 80S/Ag. The increased pH values after immersion in simulated body fluid would help neutralize the acidic oral environment. Our results indicate that 80S/Ag possesses remarkable antibacterial properties, hydroxyapatite formation, and increased pH values after immersion in simulated body fluid, supporting the potential therapeutic application of 80S/Ag for treating periodontal disease. [ABSTRACT FROM AUTHOR]

Key Clinical Message Aggregatibacter spp. is a rare cause for cardiac device infections. Due to limited data, the management of Aggregatibacter spp. device infections is not clearly defined but should always involve device removal and prolonged intravenous antibiotics.

The Gram-positive bacterium, Filifactor alocis is an oral pathogen, and approximately 50% of known strains encode a recently identified repeat-in-toxin (RTX) protein, FtxA. By assessing a longitudinal Ghanaian study population of adolescents (10-19 years of age; mean age 13.2 years), we recently discovered a possible correlation between deep periodontal pockets measured at the two-year follow-up, presence of the ftxA gene, and a high quantity of F. alocis. To further understand the contribution of F. alocis and FtxA in periodontal disease, we used qPCR in the present study to assess the carriage loads of F. alocis and the prevalence of its ftxA gene in subgingival plaque specimens, sampled at baseline from the Ghanaian cohort (n=500). Comparing these results with the recorded clinical attachment loss (CAL) longitudinal progression data from the two-year follow up, we concluded that carriers of ftxA-positive F. alocis typically exhibited higher loads of the bacterium. Moreover, high carriage loads of F. alocis and concomitant presence of the ftxA gene were two factors that were both associated with an enhanced prevalence of CAL progression. Interestingly, CAL progression appeared to be further promoted upon the simultaneous presence of F. alocis and the non-JP2 genotype of Aggregatibacter actinomycetemcomitans. Taken together, our present findings are consistent with the notion that F. alocis and its ftxA gene promotes CAL during periodontal disease.

Background Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are pathogenic bacteria of the oral cavity that cause various diseases such as periodontitis and endodontics. These bacteria are easily resistant to antibiotics. Photodynamic inactivation (PDI) is a method of inactivating microorganisms that utilizes light to activate a photosensitizer agent (PS) that produces reactive oxygen species causing cell lysis. Methods This study used the PDI method with a 405 nm diode laser at various energy density with the addition PS curcumin or chlorophyll Alfalfa, as much as 1.6 mg/ml on A. actinomycetemcomitans and E. faecalis bacteria. Results The study on E. faecalis bacteria showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of E. faecalis bacteria death 36.7% without PS, 69.30% with the addition of chlorophyll Medicago sativa L and 89.42% with the addition of curcumin. Meanwhile, the bacteria A. actinomycetemcomitans showed that the energy density diode laser irradiation of 1.59 J/cm² gave the percentage of bacterial death 35.81% without PS, 64.39% with the addition of chlorophyll Medicago sativa L and 89.82% with the addition of curcumin. PS was critical to the success of the PDI. Conclusions The addition of PS curcumin increased the effectiveness of reducing bacteria E. faecalis and A. actinomycetemcomitans compared to chlorophyll Medicago sativa L.

Aggregatibacter actinomycetemcomitans (A. actinomycetecomitans) is a Gram-negative bacterial species that is an essential component of the oral microbiota. Due to its aggregative properties, it plays a role in the pathogenesis of human diseases. The presence of the surface proteins Fim, Briae, and microvesicles enables the bacterium to adhere to the epithelial surface and the tooth’s surface. The presence of leukotoxin A (LtxA), which plays an important role in the pathogenicity of the bacterium, has been associated with both periodontitis and the etiology of rheumatoid arthritis (RA). A. actinomycetecomitans is also associated with several other systemic diseases and complications, such as endocarditis and different abscesses. In addition to leukotoxin A, A. actinomycetecomitans possesses several different virulence factors, including bacteriocins, chemotaxis inhibitory factors, cytotoxic factors, Fc-binding proteins, immunosuppressive factors, lipopolysaccharide collagenase, fibroblast inhibitory factors, antibiotic resistance determinants, adhesins, invasive factors and factors that inhibit the function of polymorphonuclear leukocytes. The ability of A. actinomycetemcomitans lipopolysaccharide to induce macrophages to secrete the interleukins IL-1, IL-1β, and tumor necrosis factor (TNF) is of considerable importance. The primary etiologic factor in the pathogenesis of periodontal disease is the oral biofilm colonized by anaerobic bacteria. Among these, A. actinomycetemcomitans occupies an important place as a facultative anaerobic bacterium. In addition, A. actinomycetemcomitans possesses many virulence factors that contribute to its potential to cause cancer. This article provides an overview of the virulence factors of A. actinomycetecomitans and its association with various systemic diseases, its oncogenic potential, and the treatment options for infections caused by A. actinomycetecomitans.

Aggressive forms of periodontitis, especially in young patients, are often associated with an increased proportion of the Gram-negative bacterium Aggregatibacter actinomycetemcomitans of the microbiota of the affected periodontal sites. One of the virulence factors of A. actinomycetemcomitans is a leukotoxin (LtxA) that induces a pro-inflammatory cell death process in leukocytes. A. actinomycetemcomitans exhibits a large genetic diversity and different genotypes vary in LtxA production capacity. The genotype JP2 is a heavy LtxA producer due to a 530-base pair deletion in the promoter for the toxin genes, and this trait has been associated with an increased pathogenic potential. The present study focused on the production and release of LtxA by different A. actinomycetemcomitans genotypes and serotypes under various growth conditions. Four different strains of this bacterium were cultured in two different culture broths, and the amount of LtxA bound to the bacterial surface or released into the broths was determined. The cultures were examined during the logarithmic and the early stationary phases of growth. The JP2 genotype exhibited the highest LtxA production among the strains tested, and production was not affected by the growth phase. The opposite was observed with the other strains. The composition of the culture broth had no effect on the growth pattern of the tested strains. However, the abundant release of LtxA from the bacterial surface into the culture broth was found in the presence of horse serum. Besides confirming the enhanced leucotoxicity of the JP2 genotype, the study provides new data on LtxA production in the logarithmic and stationary phases of growth and the effect of media composition on the release of the toxin from the bacterial membrane.

ABSTRACT Bacteria rely on extracellular chemical cues to sense their environment, interact with one another, and shape their chemical landscape. Understanding this biochemistry can help us elucidate the mechanisms by which bacterial interactions impact community function. By applying mass spectrometry to mono- and co-cultures of the oral pathogen Aggregatibacter actinomycetemcomitans and the oral commensal Streptococcus gordonii, we identified hundreds of extracellular small molecules produced by these bacteria. We discovered that A. actinomycetemcomitans secretes millimolar amounts of glutathione and identified a five-gene operon (called gttABCDE) that is important for maximum secretion. The metabolomics data set generated in this study provides a valuable data set for unraveling the importance of individual molecules for mediating polymicrobial interactions in the oral cavity. IMPORTANCE Microbes produce a large array of extracellular molecules, which serve as signals and cues to promote polymicrobial interactions and alter the function of microbial communities. This has been particularly well studied in the human oral microbiome, where key metabolites have been shown to impact both health and disease. Here, we used an untargeted mass spectrometry approach to comprehensively assess the extracellular metabolome of the pathogen Aggregatibacter actinomycetemcomitans and the commensal Streptococcus gordonii during mono- and co-culture. We generated and made publicly available a metabolomic data set that includes hundreds of potential metabolites and leveraged this data set to identify an operon important for glutathione secretion in A. actinomycetemcomitans.

Cytolethal distending toxins (Cdt) are a family of toxins produced by several human pathogens which infect mucocutaneous tissue and induce inflammatory disease. Human macrophages exposed to Aggregatibacter actinomycetemcomitans (Aa) Cdt respond through canonical and non-canonical inflammasome activation to stimulate cytokine release. The inflammatory response is dependent on PI3K signaling blockade via the toxin's phosphatidylinositol-3,4,5-triphosphate (PIP3) phosphatase activity; converting PIP3 to phosphatidylinsoitol-3,4-diphosphate (PI3,4P2) thereby depleting PIP3 pools. Phosphoinositides, also play a critical role in phagosome trafficking, serving as binding domains for effector proteins during phagosome maturation and subsequent fusion with lysosomes. We now demonstrate that AaCdt manipulates the phosphoinositide (PI) pools of phagosome membranes and alters Rab5 association. Exposure of macrophages to AaCdt slowed phagosome maturation and decreased phago-lysosome formation, thereby compromising macrophage phagocytic function. Moreover, macrophages exposed to Cdt showed decreased bactericidal capacity leading to increase in Aggregatibacter actinomycetemcomitans survival. Thus, Cdt may contribute to increased susceptibility to bacterial infection. These studies uncover an underexplored aspect of Cdt function and provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt-producing organisms such as Aa. [ABSTRACT FROM AUTHOR]

Aim: Black extrinsic tooth stain (BETS) is a health challenge that commonly affects children. Aggregatibacter actinomycetemcomitans (Aa) presents in higher prevalence within the polymicrobial community of BETS. In this study, the anti-planktonic and anti-sessile activities of cinnamon essential oil (CEO) and its individual compounds against Aa were evaluated. The preventive effect of CEO and its active substances on BETS formation was also studied in vitro. Methods: Aa was isolated from a preschool child with BETS and was identified based on the morphological characteristics, MALDI-TOF mass spectroscopy and 16S rRNA sequencing. The effect of CEO and its individual compounds on the growth kinetics of planktonic and sessile Aa cells as well as their antibacterial efficacy and their rate of bacterial killing were examined. The preventive effect of CEO and its active substances on the formation of BETS was evaluated using an ex vivo model. The data were analysed using one-way analysis of variance (ANOVA) and the significance level was set at p < 0.05. Results: Out of eight individual compounds of CEO, only eugenol, cinnamaldehyde and α-methyl cinnamaldehyde showed anti-Aa activities. The values of the minimum inhibitory concentrations (MICs) were in the following order: CEO (421.5 mg/ml) > α-methyl cinnamaldehyde (26.37 mg/ml) > cinnamaldehyde (0.209 mg/ml) > eugenol (0.052 mg/ml). CEO, eugenol, cinnamaldehyde and α-methyl cinnamaldehyde, respectively, exhibited two-, four-, four- and eightfold increase of sessile MIC compared to their planktonic MIC. The growth kinetics of both planktonic and sessile Aa in the presence of CEO, eugenol, cinnamaldehyde and α-methyl cinnamaldehyde revealed a complete inhibition at the MICs and 5.3%–37.4% biofilm inhibition at sub-MICs. The time-killing study demonstrated that CEO, eugenol and cinnamaldehyde were capable of reducing the survival rate of both planktonic and sessile Aa cells after 15–20 and 25–30 min, respectively. However, α-methyl cinnamaldehyde showed a superior anti-planktonic to anti-biofilm activity. The daily incorporation of CEO, eugenol and cinnamaldehyde at their MICs for 14 days totally prevented the formation of BETS in the ex vivo model; however, in the case of α-methyl cinnamaldehyde, BETS was visually detectable after 10 days. Conclusion: CEO and its individual compounds have marked antibacterial activity against Aa. The effective results against planktonic and sessile Aa within reasonable time indicate that they can be used to prevent BETS. [ABSTRACT FROM AUTHOR]

This study compared the cytotoxicity and antimicrobial activity of hypochlorous acid (HOCl) at 50 ppm and 200 ppm and 0.2% chlorhexidine (CHX) at various time intervals, in vitro. Cell viability and cytotoxicity of human gingival fibroblasts (HGF) were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and the lactate dehydrogenase assay. Antimicrobial effects on Aggregatibacter actinomycetemcomitans and Candida albicans were determined using the time-kill method. All solutions exhibited a significant impact on HGFs in a dose- and time-dependent manner. 50 ppm HOCl demonstrated the highest cell viability, followed by 200 ppm HOCl. Both HOCl solutions were less cytotoxic to HGFs than 0.2% CHX. 50 ppm and 200 ppm HOCl demonstrated stronger efficiencies than CHX against A. actinomycetemcomitans and C. albicans. The data suggest that HOCl solutions have potential as an alternative antiseptic to CHX due to their lower cytotoxicity and superior antimicrobial activity, but optimal dosage of HOCl requires further investigations. [ABSTRACT FROM AUTHOR]