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Introduction: N95 Filtering Face-piece Respirators (FFRs) prevent the spread of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection and protect medical personnel. It is considered as one of the essential protective equipment. An increased demand for N95 FFRs during the Coronavirus Disease 2019 (COVID-19) pandemic has resulted in shortage crisis for the care of cases arising in hospitals. Therefore, this situation generated the need to implement alternatives like four mask policy that allows reuse of N95 FFRs in settings with limited resources. Aim: To find out the burden of bacterial isolates on N95 FFRs after reuse. Materials and Methods: The present study was a prospective study conducted at Govt. R.D.B.P. Jaipuria hospital, Jaipur, Rajasthan, India, from May 2021 to October 2021 on 526 used N95 FFRs after multiple or extended use by 96 hospital personnel who attended Outpatient Department (OPD) services. Swab samples were collected from both external as well as internal surface of the mask after each use and further subcultured to identify any microorganism present on them. Results: Growth of Gram positive bacilli, and micrococci were found on 499 samples out of total 526 samples. Other bacteria like Pseudomonas spp. and other gram negative were also observed in 19 samples. Furthermore, it was also observed that bacterial load on reused N95 FFRs was mainly commensal flora. Conclusion: Mainly commensal floras were found over internal and external surface of used N95 FFRs. This proves that four mask policy is optimum for judicious use of N95 FFRs and resulted in saving of funds for other more emergency works mainly in OPD settings.

Introduction: N95 Filtering Face-piece Respirators (FFRs) prevent the spread of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection and protect medical personnel. It is considered as one of the essential protective equipment. An increased demand for N95 FFRs during the Coronavirus Disease 2019 (COVID-19) pandemic has resulted in shortage crisis for the care of cases arising in hospitals. Therefore, this situation generated the need to implement alternatives like four mask policy that allows reuse of N95 FFRs in settings with limited resources. Aim: To find out the burden of bacterial isolates on N95 FFRs after reuse. Materials and Methods: The present study was a prospective study conducted at Govt. R.D.B.P. Jaipuria hospital, Jaipur, Rajasthan, India, from May 2021 to October 2021 on 526 used N95 FFRs after multiple or extended use by 96 hospital personnel who attended Outpatient Department (OPD) services. Swab samples were collected from both external as well as internal surface of the mask after each use and further subcultured to identify any microorganism present on them. Results: Growth of Gram positive bacilli, and micrococci were found on 499 samples out of total 526 samples. Other bacteria like Pseudomonas spp. and other gram negative were also observed in 19 samples. Furthermore, it was also observed that bacterial load on reused N95 FFRs was mainly commensal flora. Conclusion: Mainly commensal floras were found over internal and external surface of used N95 FFRs. This proves that four mask policy is optimum for judicious use of N95 FFRs and resulted in saving of funds for other more emergency works mainly in OPD settings. [ABSTRACT FROM AUTHOR]

The oral cavity is habitat to a wide variety of commensal flora, which may act as a reservoir of factors that influence drug resistance. Bacteria in the oral cavity create biofilms, which makes it easier for horizontal gene transfer to result in the accumulation of antibiotic resistance genes. Methicillin-resistant Staphylococcus aureus (MRSA) carriage rates in the oral cavity are high, according to recent studies. The widespread use of antibiotic prophylaxis among at-risk dental procedure applicants may facilitate MRSA establishment in the mouth. These modifications in the epidemiology of MRSA have significant ramifications for clinical practice, methodological approaches to MRSA carriage studies, and MRSA prevention efforts. [ABSTRACT FROM AUTHOR]

Objective: To explore the common differential flora of IgAN, Kawasaki disease and IgA vasculitis by screening and analyzing the differential intestinal flora between the three disease groups of IgAN, Kawasaki disease and IgA vasculitis and their healthy controls. Methods: Papers on 16srRNA sequencing-related intestinal flora of IgAN, Kawasaki disease and IgA vasculitis were searched in databases, the literature was systematically collated and analysed, the original data was download from the relevant databases, and then the operational taxonomic unit and species classification analysis were performed. Besides, Alpha diversity analysis and Beta diversity analysis were performed to screen for IgAN, Kawasaki disease and I1gA vasculitis groups and finally compare the common intestinal differential flora among the three groups. Results: Among the common differential flora screened, Lachnospiracea_ incertae_sedis was lower in both the IgAN and Kawasaki disease groups than in the respective healthy controls; Coprococcus was low in the IgAN group but high in the IgA vasculitis group. Fusicatenibacter was lower in both the Kawasaki disease and IgA vasculitis groups than in their respective healthy controls, and Intestinibacter was low in the Kawasaki disease group, but its expression was high in the IgA vasculitis group. Conclusion: The dysbiosis of the intestinal flora in the three groups of patients with IgAN, Kawasaki disease and IgA vasculitis, its effect on the immunity of the organism and its role in the development of each disease group remain unclear, and the presence of their common differential flora may further provide new ideas for the association of the pathogenesis of the three diseases. [ABSTRACT FROM AUTHOR]

The increase of multidrug-resistant (MDR) bacteria has renewed interest in old antibiotics, such as minocycline, that can be active against various MDR Gram-negative pathogens. The elimination of minocycline by both kidneys and liver makes it suitable for impaired renal function patients. However, the drawback is the possible elimination of a high amount of drug in the intestines, with potential impact on the digestive microbiota during treatment. This study aimed to predict the potential activity of minocycline against Enterobacterales in the gut after parenteral administration, by combining in vivo and in vitro studies. Total minocycline concentrations were determined by UPLC-UV in the plasma and intestinal content of piglets following intravenous administration. In parallel, the in vitro activity of minocycline was assessed against two Escherichia coli strains in sterilized intestinal contents, and compared to activity in a standard broth. We found that minocycline concentrations were 6–39 times higher in intestinal contents than plasma. Furthermore, minocycline was 5- to 245-fold less active in large intestine content than in a standard broth. Using this PK-PD approach, we propose a preclinical pig model describing the link between systemic and gut exposure to minocycline, and exploring its activity against intestinal Enterobacterales by taking into account the impact of intestinal contents.

Actinomyces turicensis was first identified in 1995. To the best of our knowledge, pleural empyema caused by A. turicensis has never been reported. In the case reported herein, a patient with pleural empyema was treated surgically, and in the bacterial samples, A. turicensis was isolated.

The increase of multidrug-resistant (MDR) bacteria has renewed interest in old antibiotics, such as minocycline, that can be active against various MDR Gram-negative pathogens. The elimination of minocycline by both kidneys and liver makes it suitable for impaired renal function patients. However, the drawback is the possible elimination of a high amount of drug in the intestines, with potential impact on the digestive microbiota during treatment. This study aimed to predict the potential activity of minocycline against Enterobacterales in the gut after parenteral administration, by combining in vivo and in vitro studies. Total minocycline concentrations were determined by UPLC-UV in the plasma and intestinal content of piglets following intravenous administration. In parallel, the in vitro activity of minocycline was assessed against two Escherichia coli strains in sterilized intestinal contents, and compared to activity in a standard broth. We found that minocycline concentrations were 6–39 times higher in intestinal contents than plasma. Furthermore, minocycline was 5- to 245-fold less active in large intestine content than in a standard broth. Using this PK-PD approach, we propose a preclinical pig model describing the link between systemic and gut exposure to minocycline, and exploring its activity against intestinal Enterobacterales by taking into account the impact of intestinal contents. [ABSTRACT FROM AUTHOR]

Although Escherichia coli is a part of the commensal flora of the gastrointestinal tract, pathogenic types of E. coli can cause diarrhea, especially in children. Pathogenic types are found also in healthy individuals, but prevalence of pathogenic E. coli among asymptomatic children varies and has not been studied in Latvia. The aim of the study was to determine prevalence of pathogenic E. coli among asymptomatic children and identify factors associated with presence of bacterium. Children (aged 0.5–8 years) without acute gastrointestinal symptoms were included in a cross-sectional study. Parents were asked to answer a questionnaire (demographic data, parental education, type of delivery, breastfeeding, antibacterial therapy, and allergic diseases) and bring a faecal sample of their child. The prevalence of pathogenic E. coli was detected by polymerase chain reaction and analysed in respect to risk factors. Statistical analyses included Chi-Square test, one-way ANOVA, and logistic regression. The patient sample group contained 245 children, mean age 4.5 SD ± 2.1; 46.5% (114/245) had allergies. In total, 16% (39/245) of isolates were positive for pathogenic E. coli. Prevalence of pathogenic types of E. coli was significantly higher among children without allergy compared to children with allergy: 21% (27/131) vs. 11% (12/114), p = 0.03. Prevalence did not differ significantly in respect to other studied factors. In logistic regression analysis pathogenic E. coli positivity was inversely associated with presence of allergy (OR = 0.45, CI: 0.21–0.94, p = 0.03). Asymptomatic carriage of pathogenic E. coli was identified in our paediatric patient sample and was inversely associated with an allergic disease. Microbiota changes related to pathogenic E. coli, as well as duration of carriage of bacterium, should be studied further. [ABSTRACT FROM AUTHOR]

The intestinal microbiota is a complex microbial community, with diverse and stable populations hosted by the gastrointestinal tract since birth. This ecosystem holds multiple anti-infectious, anti-inflammatory, and immune modulating roles decisive for intestinal homeostasis. Among these, colonization resistance refers to the dynamic antagonistic interactions between commensals and pathogenic flora. Hence, gut bacteria compete for the same intestinal niches and substrates, while also releasing antimicrobial substances such as bacteriocines and changing the environmental conditions. Short chain fatty acids (SCFAs) generated in anaerobic conditions prompt epigenetic regulatory mechanisms that favor a tolerogenic immune response. In addition, the commensal flora is involved in the synthesis of bactericidal products, namely secondary biliary acids or antimicrobial peptides (AMPs) such as cathellicidin-LL37, an immunomodulatory, antimicrobial, and wound healing peptide. Gut microbiota is protected through symbiotic relations with the hosting organism and by quorum sensing, a specific cell-to-cell communication system. Any alterations of these relationships favor the uncontrollable multiplication of the resident pathobionts or external entero-pathogens, prompting systemic translocations, inflammatory reactions, or exacerbations of bacterial virulence mechanisms (T6SS, T3SS) and ultimately lead to gastrointestinal or systemic infections. The article describes the metabolic and immunological mechanisms through which the intestinal microbiota is both an ally of the organism against enteric pathogens and an enemy that favors the development of infections.

It is now well appreciated that the human microbiome plays a significant role in a number of processes in the body, significantly affecting its metabolic, inflammatory, and immune homeostasis. Recent research has revealed that almost every mucosal surface in the human body is associated with a resident commensal microbiome of its own. While the gut microbiome and its role in regulation of host metabolism along with its alteration in a disease state has been well studied, there is a lacuna in understanding the resident microbiota of other mucosal surfaces. Among these, the scientific information on the role of lung microbiota in pulmonary diseases is currently severely limited. Historically, lungs have been considered to be sterile and lung diseases have only been studied in the context of bacterial pathogenesis. Recently however, studies have revealed a resilient microbiome in the upper and lower respiratory tracts and there is increased evidence on its central role in respiratory diseases. Knowledge of lung microbiome and its metabolic fallout (local and systemic) is still in its nascent stages and attracting immense interest in recent times. In this review, we will provide a perspective on lung‐associated metabolic disorders defined for lung diseases (e.g., chronic obstructive pulmonary disease, asthma, and respiratory depression due to infection) and correlate it with lung microbial perturbation. Such perturbations may be due to altered biochemical or metabolic stress as well. Finally, we will draw evidence from microbiome and classical microbiology literature to demonstrate how specific lung morbidities associate with specific metabolic characteristics of the disease, and with the role of microbiome in this context. © 2018 IUBMB Life, 71(1):152–165, 2019 [ABSTRACT FROM AUTHOR]

The intestinal microbiota is a complex microbial community, with diverse and stable populations hosted by the gastrointestinal tract since birth. This ecosystem holds multiple anti-infectious, anti-inflammatory, and immune modulating roles decisive for intestinal homeostasis. Among these, colonization resistance refers to the dynamic antagonistic interactions between commensals and pathogenic flora. Hence, gut bacteria compete for the same intestinal niches and substrates, while also releasing antimicrobial substances such as bacteriocines and changing the environmental conditions. Short chain fatty acids (SCFAs) generated in anaerobic conditions prompt epigenetic regulatory mechanisms that favor a tolerogenic immune response. In addition, the commensal flora is involved in the synthesis of bactericidal products, namely secondary biliary acids or antimicrobial peptides (AMPs) such as cathellicidin-LL37, an immunomodulatory, antimicrobial, and wound healing peptide. Gut microbiota is protected through symbiotic relations with the hosting organism and by quorum sensing, a specific cell-to-cell communication system. Any alterations of these relationships favor the uncontrollable multiplication of the resident pathobionts or external entero-pathogens, prompting systemic translocations, inflammatory reactions, or exacerbations of bacterial virulence mechanisms (T6SS, T3SS) and ultimately lead to gastrointestinal or systemic infections. The article describes the metabolic and immunological mechanisms through which the intestinal microbiota is both an ally of the organism against enteric pathogens and an enemy that favors the development of infections. [ABSTRACT FROM AUTHOR]

Background: Bacterial conjunctivitis is a microbial infection of the mucous membrane of the conjunctiva of eye that occurs both in adults and children. It is produced by an array of microorganisms that is frequently isolated from the conjunctiva of healthy subjects. The normal conjunctival flora represents both bacterial colonization and transient or recurring bacterial contamination. Coagulase-negative Staphylococci and Corynebacteria are frequently present on the healthy conjunctiva, but more traditionally pathogenic organisms, such as coagulase-positive Staphylococci, Streptococci, Haemophilus species, Moraxellae and Gram negative coliform rods occasionally isolated from normal, non-inflamed eyes. Objective: To determine etiological agents of aerobic bacterial conjunctivitis and the prevalence of each bacteria and its relation with the conjunctival discharge. Methods: This study conducted on 100 conjunctival samples from patients with conjunctivitis, and 50 samples from healthy normal persons. All samples were cultured on enriched media like blood agar and chocolate agar, anti-microbial susceptibility of all 100 samples from patients were analyzed. Results: The prevalence of aerobic bacterial conjunctivitis is 53 %with predominance age of 1-10 years. The most common bacterial isolates were Staphylococcus epidermidis followed by Streptococcus pneumonia. Most of the isolates were sensitive to cefotaxime and ofloxacillin, while different result was detected regarding resistance of each isolated bacteria. Conclusion: Aerobic bacterial isolates can be detected both in conjunctivitis and normal healthy individual with similarity regarding the type of bacteria that affect all age group. [ABSTRACT FROM AUTHOR]

The human intestinal microbiota plays a major beneficial role in immune development and resistance to pathogens. The use of antibiotics, however, can cause the spread of antibiotic resistance genes within the resident intestinal microbiota. Important vectors for this are integrons. This review therefore focuses on the integrons in non-pathogenic bacteria as a potential source for the development and persistence of multidrug resistance. Integrons are a group of genetic elements which are assembly platforms that can capture specific gene cassettes and express them. Integrons in pathogenic bacteria have been extensively investigated, while integrons in the intestinal microbiota have not yet gained much attention. Knowledge of the integrons residing in the microbiota, however, can potentially aid in controlling the spread of antibiotic resistance genes to pathogens.

Los síntomas compatibles con vaginitis y vaginosis, son la causa más frecuente de consulta al ginecólogo. La descarga vaginal abundante y el prurito, constituyen la primera sospecha de estas patologías. Sin embargo, debemos tener presente que el aumento significativo de lactobacilos, conocido como lactobacilosis, puede expresarse también con los mismos síntomas y signos de una vulvovaginitis micótica. Si esta condición se mantiene en el tiempo, puede provocar un grado de acidez anormal en la vagina, y puede llevar a una lisis de las células epiteliales que se conoce como vaginosis citolítica. Este diagnóstico, aunque es poco frecuente, debemos sospecharlo especialmente, en aquellas mujeres que relatan tener múltiples consultas por candidiasis vaginal, con escasa o nula respuesta frente a la terapia antimicótica.The symptoms consistent with vaginitis and vaginosis are the most common cause of the visit to the gynecologist. Heavy vaginal discharge and pruritus are the first suspicion of this pathology. However, the significant increase in lactobacilli, known as lactobacilosis can be expressed also with the same symptoms and signs of a fungal vulvovaginitis. If this condition is maintained overtime, can cause abnormal acidity in the vagina, and may lead to epithelial cell lysis, which is known as cytolytic vaginosis. This diagnosis, although rare, should be suspected especially in women who reported having multiple consultations for vaginal candidiasis, with little or no response to antifungal therapy.

Despite great medical advances in preventing maternal and infant mortality in the past century, one issue remains unresolved: why do so many women give birth prematurely? A major new field of human microbiome studies has begun to shed light on the impact of microbes (of both the commensal and pathogen varieties) on pregnancy outcomes. Recent advances in next-generation sequencing and metagenomic analysis have revealed that maternal microbiomes at a variety of niches including the oral, vaginal, gut, cervical, and even the placenta itself govern pregnancy outcomes. In this review, we describe how alterations in the microbial biomasses impact preterm birth and we discuss the major research questions concerning the cause and/or interdependent relationships between microbiome, infection, and preterm delivery. [ABSTRACT FROM AUTHOR]

The etiopathogenesis of many autoimmune disorders has not been identified. The aim of this paper is to focus on the involvement of bacterial exposure, as an environmental factor, in the pathogenesis of autoimmune pancreatitis (AIP), which is broadly categorized as autoimmune disorders involving pancreatic lesions. Avirulent and/or commensal bacteria, which may have an important role(s) as initiating/progressing factors in the pathogenesis of autoimmune disorder AIP, will be emphasized.

Commensal microflora engages in a symbiotic relationship with their host, and plays an important role in the development of colorectal cancer (CRC). Pathogenic bacteria promote chronic intestinal inflammation and accelerate tumorigenesis. In sporadic CRC, loss of an effective epithelial barrier occurs at early stage of CRC development. As a result, non-pathogenic bacteria and/or their products infiltrate tumor stroma, drive "tumor-elicited inflammation" and promote CRC progression by activating tumor-associated myeloid and immune cells that produce IL-23 and IL-17. In this article we will summarize the recent advances in understanding the relationship between gut flora and CRC. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae is an important cause of invasive infections in neonates and is emerging as an important pathogen in elderly females. S. agalactiae is a commensal organism of the female genital tract; however, isolation from the uterine cavity suggests ascending infection of this organism caused by occlusion of the uterine cavity. We report a case of S. agalactiae causing pyometra in an elderly female with cervical cancer. [ABSTRACT FROM AUTHOR]

Nasal exposure to the mixture of microbial extracts (MME) after ablactation enhanced airway resistance of newborn mice to Streptococcus pneumoniae (J Physiol Lung Cell Mol Physiol 298: L67, 2010). The present study was addressed to elucidate effective factors responsible for the enhanced innate resistance in the airway of MME-exposed newborn mice. MME exposure significantly increased the amount of pulmonary surfactants (SP-A and SP-D) in the airway. Bronchoalveolar lavage fluid of the exposed mice exhibited greater levels of opsonic activity, thereby enhancing the phagocytic and intracellular killing activities of alveolar macrophages (MØ) against S. pneumoniae. The exposure itself did not increase a complement component C3 and mannan-binding lectin-A (MBL-A) in the airway, whereas intratracheal infection with S. pneumoniae increased the quantity of SP-A, SP-D, C3, and MBL-A in the exposed mice to a significant extent compared with control mice. The exposure enhanced the expression of the class A scavenger MØ receptor with collagenous structure on alveolar MØ and also increased the frequency of major histocompatibility complex IIØ CD11c+ cells in the lung; the cells were able to produce IL-10 and transforming growth factor-β in vitro. These results suggest that microbial exposure early in life increases the amounts of SP-A and SP-D and the number of scavenger MØ and also promotes maturation of CD11c+ cells in the airway of newborn mice, which may be involved in airway resistance to S. pneumoniae. [ABSTRACT FROM AUTHOR]

Alpha-Gal is a glycoconjugate present on cell membranes of non-primate mammals and bacteria, but not in humans, who display anti-Gal antibodies (ABs) in high titres. Probiotics contain bacterial strains which colonize the intestinal tract. In the present study, we investigated whether intake of fermented milk containing Lactobacillus casei (FML) affects anti-Gal AB titres. Serum was drawn from healthy probands ( n == 19) for 6 weeks. After the second week, the probands consumed 125 ml of FML per day. Anti-Gal ABs of all isotypes and cytokines were measured. Bacterial cultures were bred from FML and bacteria were stained for alpha-Gal. Concentration of bacteria in FML was manifold higher than in conventional yoghurt (2 × 105/g yoghurt vs. 1.1 × 107/g FML). Both stained highly positive for Alpha-Gal. Alpha-Gal-specific ABs and cytokines remained unaffected by FML intake. Our results indicated that the consumption of FML does not elicit a humoral immune response in healthy adults. [ABSTRACT FROM AUTHOR]

A prospective cohort study of preschool healthy children (3–6 years old) from two distinct socio-economic settings in the Brussels area, Belgium, was conducted during the years 2006–2008. The objectives were to evaluate nasopharyngeal colonization by Streptococcus pneumoniae, Staphylococcus aureus, Moraxella catarrhalis and Haemophilus influenzae at the time of PCV7 vaccine introduction and to assess the socio-economic level impact on flora composition and antibiotic resistance. Three hundred and thirty-three children were included and a total of 830 nasopharyngeal samples were collected together with epidemiological data. Pneumococcal serotypes and antibiotic resistance profiles were determined. Risk factors for carriage and bacterial associations were analysed by multivariate logistic regression. Carriage rates were high for all pathogens. Fifty per cent of the children were colonized at least once with S. aureus, 69% with S. pneumoniae, 67% with M. catarrhalis and 83% with H. influenzae. PCV7 uptake was higher among children from a higher socioeconomic setting and S. pneumoniae serotypes varied accordingly. Children from lower socio-economic schools were more likely to carry M. catarrhalis, S. aureus and antibiotic-resistant S. pneumoniae, including a high proportion of non-typeable pneumococcal strains. Positive associations between S. pneumoniae and H. Influenza, between H. influenzae and M. catarrhalis and between H. influenzae and S. aureus were detected. Our study indicates that nasopharynx flora composition is influenced not only by age but also by socioeconomic settings. A child’s nasopharynx might represent a unique dynamic environment modulated by intricate interactions between bacterial species, host immune system and PCV7 immunization. [ABSTRACT FROM AUTHOR]

Nod2 is an intracellular pattern recognition receptor binding bacterial wall muramyl dipeptide (MDP) and inducing NF-kB activation via the Rip2 pathway. NOD2 variants have been found to be the most important genetic susceptibility factor for the development of Crohn's disease. Nod2 is expressed in the Paneth cells of the small intestine and in antigen-presenting cells of the mucosal innate immune system. Furthermore, Nod2 is a regulator of a number of secreted antimicrobial proteins such as defensins. Subsequently, the question was raised whether Nod2 activity (or a loss of activity in Nod2 variants) influences the composition of the intestinal commensal flora. The Nod2 ligand MDP is able to induce bacterial killing when intestinal crypts are incubated with MDP and the supernatants are used for microbial killing activity assays, thus indicating that upregulation of Nod2 activity induces antimicrobial activity. In Nod2-deficient crypts, the ability to kill bacteria is reduced. Consequently, the commensal bacterial flora in Nod2-deficient mice differs from that seen in wild-type mice and, in general, is found to be increased in load. Nod2 activity influences the colonization of the mucosal wall by potentially pathogenic bacteria; the commensal flora, on the other hand, influence the expression of Nod2. This indicates a balanced system in which commensal bacteria and Nod2-mediated pathways influence each other to achieve a steady state without inflammation. The controlled balance between Nod2 and the commensal flora creates a negative-feedback loop in which the bacteria positively regulate Nod2 and associated signaling molecules, which in turn regulate the commensal flora. This pathway is likely to be one of the regulative loops that exist between the intestinal flora and the gut immune system. INSET: Key issues. [ABSTRACT FROM AUTHOR]

Intestinal macrophages, preferentially located in the subepithelial lamina propria, represent the largest pool of tissue macrophages in humans. As an adaptation to the local antigen- and bacteria-rich environment, intestinal macrophages exhibit several distinct phenotypic and functional characteristics. Notably, microbe-associated molecular pattern receptors, including the lipopolysaccharide (LPS) receptors CD14 and TLR4, and also the Fc receptors for IgA and IgG are absent on most intestinal macrophages under homeostatic conditions. Moreover, while macrophages in the intestinal mucosa are refractory to the induction of proinflammatory cytokine secretion, they still display potent phagocytic activity. These adaptations allow intestinal macrophages to comply with their main task, i.e., the efficient removal of microbes while maintaining local tissue homeostasis. In this paper, we review recent findings on the functional differentiation of monocyte subsets into distinct macrophage populations and on the phenotypic and functional adaptations that have evolved in intestinal macrophages in response to their antigen-rich environment. Furthermore, the involvement of intestinal macrophages in the pathogenesis of celiac disease and inflammatory bowel diseases is discussed. [ABSTRACT FROM AUTHOR]

Objectives: We examined the microbiology and antimicrobial susceptibility patterns of commensal flora in the middle nasal meatus of normal subjects who were free of health care-associated risks and sinonasal disease. Methods: A prospective study was performed on 70 healthy volunteers without health care-associated risks or sinonasal disease. Middle meatal specimens were carefully taken by an endoscopically guided swab technique. The specimens were cultured for aerobic and anaerobic bacteria. Antimicrobial susceptibility testing was performed by the broth disc method. Results: Bacterial growths were recovered in 66 of the 70 specimens (94.3%). Coagulase-negative staphylococci (CNS) were the most common isolates (61.6%), followed by Staphylococcus aureus (11.6%) and Corynebacterium sp (9.3%). All growths were quantified as very rare (73.3%), rare (13.9%), or few (12.8%). Obligate anaerobic bacteria were not identified. The samples positive for CNS showed multiple resistances to antibiotics, including erythromycin stearate (30.2%), clindamycin hydrochloride (28.3%), oxacillin sodium (a clinical substitute for methicillin sodium; 18.9%), and sulfamethoxazole-trimethoprim (9.4%). Conclusions: A small amount of CNS with or without multiple antibiotic resistances and/or S aureus cultured from the middle meatus can be considered contaminants in middle meatal culture during an episode of rhinosinusitis. [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) play major roles in immunosurveillance. In peripheral tissues, ‘immature’ DCs are dedicated to capturing antigens. Detection of pathogens through Toll-like receptors (TLRs) triggers DC migration to the lymph nodes (LNs), where they acquire a ‘mature’ phenotype specialized at presenting antigens. However, DCs migrate from tissues and mature even in the absence of overt infections. This has been attributed to detection of commensal flora in the skin, the gut or other peripheral tissues in the steady state. To test this assumption, we have analyzed the DCs contained in the lymphoid organs of germ-free mice and of mice lacking the TLR adapter molecules, MyD88 and TRIF. We show that the proportion and expression of maturation markers in DC immigrants in the LNs of these mice are similar to those in normal mice. These results suggest that DC migration from tissues, followed by their phenotypic maturation, is regulated in the steady state by an inherent program of DC differentiation or by the release of low levels of inflammatory signals from normal tissues.Immunology and Cell Biology (2008) 86, 200–205; doi:10.1038/sj.icb.7100125; published online 20 November 2007 [ABSTRACT FROM AUTHOR]

Abstract: The gastrointestinal tract is fundamental for the uptake of nutrients and fluids, but it also represents the greatest surface of the body in contact with the external environment and most human pathogens enter the body through the mucosal surface, especially in the intestine. The intestinal immune system protects the sterile core of the organism against invasion and systemic dissemination of both pathogens and limits for level penetration of commensal microorganisms. In addition, the human intestine is continually in contact with 1014 commensal bacteria containing more than 500 different species. These commensal bacteria confer health benefits to their host by helping dietary digestion, development of gut immunity and preventing colonization by pathogens. To maintain integrity and normal function of intestine, a delicate equilibrium must be reached between the bacterial flora and intestinal immune system. This review discusses the recent advances in our understanding of how the mucosal intestinal barrier maintains a local homeostatic response to the resident intestinal bacteria, while protecting the host against enteric pathogens. In particular, the emerging function of Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in controlling mucosal immunity will be presented. [Copyright &y& Elsevier]

Immune privilege in the gut is the result of a complex interplay between the gut microbiome, gut luminal antigens, and the intestinal epithelial barrier. Composed of both physical and immunochemical components, the intestinal barrier secretes immunoregulatory mediators that promote the generation of tolerogenic antigen-presenting cells, phagocytic innate immune cells characterized by ‘inflammatory anergy’, and regulatory cells of the adaptive immune system. Innate immune cells mediate controlled transepithelial transport of luminal antigens as far as the mesenteric lymph nodes, where the intestinal and peripheral immune systems intersect. This promotes the generation of adaptive regulatory lymphocytes that actively suppress effector cell responses against gut luminal antigens and flora. The net result is the generation of tolerance to dietary antigens and the maintenance of gut homeostasis. Dysregulation of this complex immunoregulatory network leads to diseases such as food allergy and inflammatory bowel disease. Future therapies for these diseases will likely involve the functional restoration of the barrier and regulatory cell functions at the epithelial/luminal interface. [ABSTRACT FROM AUTHOR]

Abstract: Toll-like receptors (TLR) detect pathogen-associated molecular patterns (PAMP) and play a crucial role in triggering immunity. Due to their large surfaces in direct contact with the environment, mucosal tissues are the major sites of PAMP-TLR signalling. How innate and adaptive immunity are triggered through flagellin–TLR5 interaction is the main focus of the review. In view of recent reports on genetic polymorphism, we will summarize the impact of TLR5 on the susceptibility to mucosal infections and on various immuno-pathologies. Finally, the contribution of TLRs in the induction and maintenance of mucosal homeostasis and commensal discrimination is discussed. [Copyright &y& Elsevier]

Regulated mechanisms sustain the ability of the gut immune system to discriminate harmless food antigens (Ag) and commensal bacteria from pathogenic microorganisms, resulting in tolerance versus protective immunity, respectively. Antigens of the gut commensals are not simply ignored, but rather trigger an active immunosuppressive process, more commonly known as oral tolerance, which prevents the outcome of immunopathology. Both intrinsic properties of the gut microenvironment and cellular actors, as well as peripheral events induced by systemic dissemination of oral Ag, promote the induction of regulatory mechanisms that ensure maintenance of gut homeostasis. The aim of this review is to provide a synthetic update on the mechanisms of oral tolerance, with particular emphasis on the complex interplay between regulatory CD4+ T cells, dendritic cells and the gut microenvironment. [ABSTRACT FROM AUTHOR]

Abstract: Besides mainstream TCRαβ T cells harboring a very diverse repertoire, two subsets display an evolutionarily conserved invariant repertoire. This striking conservation indicates important and unique functions. CD1d-restricted NK-T cells expressing an invariant Vα14 TCRα chain have been implicated in microbial and tumor responses as well as in auto-immunity. In this review, we describe the other subset, which bears the canonical hVα7.2/mVα19-Jα33 TCRα chain paired with a restricted set of Vβ segments. These invariant T cells are present in mice, humans and cattle. They are preferentially located in the gut lamina propria (LP) of humans and mice and are therefore called mucosal-associated invariant T (MAIT) cells. Selection/expansion of this population requires B lymphocytes expressing MR1, a monomorphic major histocompatibility complex class I-related molecule that is also strikingly conserved in diverse mammalian species. MAIT cells are not present in germ-free mice, indicating that commensal flora is required for their expansion in the gut LP. The nature of the ligand and the putative functions of these MAIT cells are discussed. [Copyright &y& Elsevier]

A collection of 114 clinical Streptococcus milleri group (SMG) strains at the Ryukyu University Hospital obtained in 1999 and 2000, was identified and tested for susceptibility to 12 antibiotics. The percentage of strains with intermediate susceptibility to penicillin G was relatively high (14%). Cefaclor and cefotiam, with a MIC 90 of 2 μg/ml, were less active than cefotaxime. Strains nonsusceptible to erythromycin, clindamycin, and azithromycin were found with a frequency of 8%, 5%, and 4%, respectively. Almost all of the SMG strains were susceptible to fluoroquinolones (except for 1% of the strains nonsusceptible to levofloxacin), and sitafloxacin (DU-6859a) was the most active agent among the 12 tested antibiotics. [ABSTRACT FROM AUTHOR]

Actinomyces turicensis was first identified in 1995. To the best of our knowledge, pleural empyema caused by A. turicensis has never been reported. In the case reported herein, a patient with pleural empyema was treated surgically, and in the bacterial samples, A. turicensis was isolated. [ABSTRACT FROM AUTHOR]

Healthy CD45 KO mice show a Th2-type cytokine secretion profile in their small intestines. Dietary supplementation with human infant formula induced colitis and a shift toward a Th1-type profile, suggesting that diet can alter cytokine secretion. [ABSTRACT FROM AUTHOR]