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Zebu cattle (Bos indicus) is reported to be more resistant towards harmful environmental factors than taurine cattle (Bos taurus). A few hundred zebu cattle are kept in Switzerland and in contrast to the Swiss indigenous breeds, infectious hoof disease in zebu is not observed. Therefore, we compared the prevalence of three ruminant hoof pathogens in zebu and taurine cattle. These included Treponema spp., Fusobacterium necrophorum and Dichelobacter nodosus which are associated with bovine digital dermatitis (BDD), different bovine hoof diseases and ovine footrot, respectively. Interdigital swabs and punch biopsies from hind feet of slaughter animals were tested for the three pathogens by PCR. Sixty zebu from eight farms were compared to a convenience sample of 20 taurine cattle from 17 farms. Treponema spp. associated with BDD were not detected in zebu while 23 % of animals and 50 % of farms were positive for benign D. nodosus, with results indicating environmental contamination rather than colonization. Taurine cattle showed 35 % of animals and 41 % of farms positive for T. phagedenis while 90 % of animals and 94 % of farms were colonized by D. nodosus as indicated by a 500-fold higher bacterial load than in zebu. The difference in prevalence of the two pathogens between zebu and taurine cattle was highly significant. F. necrophorum was as well only detected in taurine cattle with values of 15 % of animals and 17.7 % of farms, being significantly different at the animal level. Furthermore, genetic analysis of Swiss zebu indicates high genomic diversity and clear separation from taurine cattle. This is the first evidence that zebu show resistance towards colonization by bacterial hoof pathogens in contrast to taurine cattle., Competing Interests: Declaration of Competing Interest None, (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Fusobacterium necrophorum is a Gram-negative anaerobic bacterium responsible for localized infections of the oropharynx that can evolve into bacteremia and/or septic thrombophlebitis of the jugular vein or peritonsillar vein, called Lemierre's syndrome. To identify microbial genetic determinants associated with the severity of this life-threatening disease, 70 F. necrophorum strains were collected and grouped into two categories according to the clinical presentation: (i) localized infection, (ii) bacteremia with/without Lemierre's syndrome. Comparative genomic analyses revealed two clades with distinct genetic content, one clade being significantly enriched with isolates from subjects with bacteremia. To identify genetic determinants contributing to F. necrophorum pathogenicity, genomic islands and virulence factor orthogroups (OVFs) were predicted. The presence/absence profiles of OVFs did not group isolates according to their clinical category, but rather according to their phylogeny. However, a variant of lktA, a key virulence factor, with a frameshift deletion that results in two open reading frames, was associated with bacteremia. Moreover, a genome-wide association study identified three orthogroups associated with bacteremic strains: (i) cas8a1, (ii) a sodium/solute symporter, and (iii) a POP1 domain-containing protein. Further studies must be performed to assess the functional impact of lktA mutation and of these orthogroups on the physiopathological mechanisms of F. necrophorum infections., (© 2024. The Author(s).)

Background: Legionella pneumonia is one of the most severe types of atypical pneumonia, impairing multiple organ systems, posing a threat to life. Diagnosing Legionella pneumonia is challenging due to difficulties in culturing the bacteria and limitations in immunoassay sensitivity and specificity., Case Presentation: This paper reports a rare case of sepsis caused by combined infection with Legionella pneumophila and Fusobacterium necrophorum, leading to respiratory failure, acute kidney injury, acute liver injury, myocardial damage, and electrolyte disorders. In addition, we systematically reviewed literature on patients with combined Legionella infections, analyzing their clinical features, laboratory results and diagnosis., Conclusions: For pathogens that require prolonged incubation periods and are less sensitive to conventional culturing methods, metagenomic next-generation sequencing (mNGS) can be a powerful supplement to pathogen screening and plays a significant role in the auxiliary diagnosis of complex infectious diseases., (© 2024. The Author(s).)

Background and Purpose: Fusobacterium necrophorum ( F necrophorum ) is an anaerobic bacteria that causes invasive head and neck infections in children. Several studies have demonstrated an increasing prevalence of F necrophorum as the causative agent in acute mastoiditis in children, with associated high rates of intracranial complications such as epidural abscess and sinus venous thrombosis, to name a few. F necrophorum requires a treatment protocol that differs from the empiric treatment that is tailored to more common pathogens (eg, group A streptococci, Streptococcus pneumonia), and hence expediting the diagnosis is important. For evaluating complicated acute mastoiditis in children, cranial CT venography remains the imaging study of choice in most medical centers due to its availability in emergency situations. Based on our clinical experience, our hypothesis is that children with F necrophorum -associated complicated acute mastoiditis can be differentiated from those with other etiologies using CT venography., Materials and Methods: CT venography studies of 76 children hospitalized and treated for complicated acute mastoiditis were retrospectively reviewed. Retrieved imaging data included intracranial complications (epidural abscess, sinus venous thrombosis), cranial bone-related complications, and extracranial complications (subperiosteal abscess, temporomandibular joint abscess, and soft-tissue inflammation). The cohort was divided into children with F necrophorum -related disease (study group) and those with non- F necrophorum -related disease (control group)., Results: Thirty-seven children (49%) comprised the study group, and 39 children in whom the causative agents were other bacteria comprised the control group. There were significantly higher rates of complications in the study group: sinus venous thrombosis ( P < .001), perisigmoid epidural abscess ( P  = .036), and extramastoid osteomyelitis ( P  < .001). Thrombosis in venous sites beyond the sigmoid sinus and jugular foramen (a pattern consistent with an otogenic variant of Lemierre syndrome) and emphysematous osteomyelitis were found only among children in the F necrophorum -related study group (32% and 22% accordingly)., Conclusions: In children with complicated acute mastoiditis, CT venography findings of emphysematous osteomyelitis and/or thrombosis in venous sites beyond the sigmoid sinus and jugular foramen (a pattern consistent with the otogenic variant of Lemierre syndrome) should lead the radiologist to suggest F necrophorum -related mastoiditis., (© 2024 by American Journal of Neuroradiology.)

Objectives: Fusobacterium necrophorum is a common cause of pharyngotonsillitis. However, no guidelines exist on when to diagnose or treat it. We aimed to investigate associations between clinical criteria and F. necrophorum-positivity in pharyngotonsillitis and assess the predictive potential of a simple scoring system., Methods: Pharyngotonsillitis patients who were tested for F. necrophorum (PCR) and presented to hospitals in the Skåne Region, Sweden, between 2013-2020 were eligible. Data were retrieved from electronic chart reviews and registries. By logistic regression we investigated associations between F. necrophorum-positivity and pre-specified criteria: age 13-30 years, symptom duration ≤ 3 days, absence of viral symptoms (e.g. cough, coryza), fever, tonsillar swelling/exudate, lymphadenopathy and CRP ≥ 50 mg/L. In secondary analyses, associated variables were weighted by strength of association into a score and its predictive accuracy of F. necrophorum was assessed., Results: Among 561 cases included, 184 (33%) had F. necrophorum, which was associated with the following criteria: age 13-30, symptom duration ≤ 3 days, absence of viral symptoms, tonsillar swelling/exudate and CRP ≥ 50 mg/L. Age 13-30 had the strongest association (OR5.7 95%CI 3.7-8.8). After weighting, these five variables had a sensitivity and specificity of 68% and 71% respectively to predict F. necrophorum-positivity at the proposed cut-off., Conclusion: Our results suggest that F. necrophorum cases presenting to hospitals might be better distinguished from other pharyngotonsillitis cases by a simple scoring system presented, with age 13-30 being the strongest predictor for F. necrophorum. Prospective studies, involving primary care settings, are needed to evaluate generalisability of findings beyond cases presenting to hospitals., (© 2024. The Author(s).)

Tonsillar Fusobacterium necrophorum PCR Ct-values were higher in participants with asymptomatic tonsillar carriage than patients with pharyngeal infections. However, Ct-values were not associated with severity of disease or predictive of development of complications and hence lacked clinical usefulness. The reporting of F. necrophorum Ct-values in clinical samples is not recommended., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Fusobacterium necrophorum causes a range of mild to life threatening infections and there is uncertainty in terms of diagnosis and treatment due to the lack of knowledge on their pathogenic mechanisms. This study characterised genomes of F. necrophorum to compare their virulence factors and investigate potential infection markers. 27 isolates of F. necrophorum from patients with pharyngotonsillitis were subjected to whole genome sequencing and compared with 42 genomes published in the NCBI database. Phylogenomics, pangemome, pan-GWAS and virulome were analysed to study strain variations with reference to virulence factors. Core genome based phylogenomic tree exhibited three clades of which Clade A belonged to F. necrophorum subsp necrophorum, clades B and C were F. necrophorum subsp funduliforme. Pan-GWAS and Pan-Virulome suggest some marker genes associated with clinical sources of isolation that needs further validation. Our study highlights some interesting features of the pathogenesis of F. necrophorum infections. Although the animal isolate genomes had some marker genes, the genomes of human isolates did not exhibit clear correlation to their clinical sources of isolation. This prompts to think of other mechanisms such as co-infections or host factors that can be involved in the pathogenesis., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Fusobacterium necrophorum can cause liver abscess, foot rot in ruminants, and Lemire syndrome in humans, Also, its virulence factors can induce the apoptosis of macrophages and neutrophils. However, the detailed mechanism has not been fully clarified. This study investigated the mechanisms of apoptosis and inflammatory factor production in F. necrophorum -induced neutrophils and macrophages (RAW246.7). After infection of macrophages with F. necrophorum , 5-ethynyl-2'-deoxyuridine labeling assays indicated that F. necrophorum inhibited macrophage proliferation in a time- and dose-dependent manner. Hoechst staining and DNA ladder assays showed significant condensation of the nucleus and fragmentation of genomic DNA in F. necrophorum -infected macrophages, Annexin V (FITC) and propidium iodide (PI) assay confirmed the emergence of apoptosis in the macrophages and sheep neutrophils with F. necrophorum compared with the control. The group with significant apoptosis was subjected to RNA sequencing (RNA-Seq), and the sequencing results revealed 2581 up- and 2907 downregulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of the differentially expressed genes showed that F. necrophorum drove apoptosis and production of inflammatory factors by activating genes related to the Nuclear Factor-κB (NF-κB) and death receptor pathways. Meanwhile, quantitative reverse transcription PCR and Western blot validation results were consistent with the results of transcriptome sequencing analysis. In conclusion, F. necrophorum induced apoptosis and production of pro-inflammatory factors through the NF-κB and death receptor signaling pathway, providing a theoretical basis for further mechanistic studies on the prevention and control of F. necrophorum disease treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Wang, Zhao, He, Jiang, Wang, Xiao, Sun and Guo.)

Fusobacterium necrophorum, a Gram-negative anaerobe, is the primary etiologic agent of liver abscesses of beef cattle. The bacterium, a member of the microbial community of the rumen, travels to the liver via portal circulation to cause abscesses. The severity of liver abscesses vary from mild with one or two small abscesses to severe with medium to large multiple abscesses. Leukotoxin, a secreted protein, is the critical virulence factor involved in the infection. Our objective was to compare leukotoxin production between strains of F. necrophorum isolated from mild and severe liver abscesses collected from slaughtered cattle. The quantification of leukotoxin was based on assays to measure cytotoxicity and protein antigen concentration. One-hundred strains, 50 from mild and 50 from severe abscesses, were utilized in the study. Cell-free supernatants were prepared from cultures grown in anaerobic broth at 9 and 24 h incubations. The leukotoxic activity was quantified by measuring cytotoxicity based on the release of lactic dehydrogenase from bovine lymphocyte cells, BL3, treated with the culture supernatant. Leukotoxin protein concentration was quantified by a sandwich ELISA assay with a leukotoxin-specific monoclonal antibody as the capture antibody. The leukotoxin activity and concentration were highly variable among the strains within each severity of liver abscesses. Although the leukotoxic activity was unaffected by incubation time, leukotoxin protein concentration was consistently higher at 24 h compared to 9 h incubation. Strains from severe liver abscesses had significantly higher leukotoxic activity and higher protein concentration compared to strains from mild liver abscesses (P < 0.0001) at both 9 and 24 h culture supernatants. Across all strains, the correlation coefficients between leukotoxic activity and leukotoxin concentration at 9 and 24 h were 0.14 (P = 0.17) and 0.47 (P < 0.0001), respectively. In conclusion, strains isolated from severe liver abscesses had significantly higher leukotoxic activities and leukotoxin protein concentrations compared to strains isolated from mild liver abscesses., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A 1-mo-old reticulated giraffe had progressive anorexia and died at the Ordos Zoo. Autopsy revealed necrotic stomatitis with severe bilateral necroulcerative lesions at the base of the tongue and of the cheeks near the commissures of the mouth. There was also severe bilateral confluent bronchopneumonia with a pronounced bronchial pattern and multifocal fibrinous pleuritis. Histologically, there was serofibrinous-suppurative bronchopneumonia with necrosuppurative bronchiolitis and necrotic arteritis. Filamentous bacteria with morphology consistent with Fusobacterium necrophorum were observed at the advancing edge of the necrotic tissue in the tongue and cheeks, as well as in the affected alveolar spaces and bronchioles. Aggregates of slender, gram-negative, rod-like or filamentous bacteria were identified in the lung impression smear. PCR results of 16S rDNA of the tongue and lung lesions had 100% homology to the F. necrophorum subsp. funduliforme B35 sequence (EF447425.1). The gross, histologic, Gram stain, and PCR product sequencing features in our case were consistent with oral and pulmonary necrobacillosis in ruminants, a rare disease of giraffes.

Ulcers of the oral cavity, esophagus, and gastric compartments of South American camelids are uncommon. Multifocal-to-coalescing ulcers were identified in the oral cavity, esophagus, and/or gastric compartments of 5 alpacas submitted for postmortem examination. Fusobacterium necrophorum was isolated from the lesions in all alpacas, in combination with other aerobic and anaerobic bacteria. In 4 of these cases, F. necrophorum -associated lesions were considered secondary to neoplasia or other chronic debilitating conditions; in 1 case, the alimentary ulcers were considered the most significant autopsy finding. It is not known if this agent acted as a primary or opportunistic agent in mucosal membranes previously damaged by a traumatic event, chemical insult, immunodeficiency, or any other debilitating condition of the host.

Objective: To evaluate in children the clinical severity and evolution of otogenic lateral sinus thrombosis (OLST) due to Fusobacterium necrophorum compared with other bacterial otogenic thrombosis and propose a specific management flowchart for Fusobacterium OLST., Design: A retrospective multicentre cohort study., Settings: Four French ENT paediatric departments., Participants: A total of 260 under 18 years old admitted for acute mastoiditis were included. Initial imaging was reviewed to focus on complicated mastoiditis and 52 OLST were identified. Children were then divided into two groups according to bacteriological results: 28 in the "OLST Fusobacterium group" and 24 in the "OLST other bacteria group"., Results: There was a significant association between F necrophorum and OLST (P < .001). When compared to the OLST other bacteria group, children in the OLST Fusobacterium group were significantly younger (61 months vs 23 months, P < .01) and had a more severe clinical presentation: higher CRP (113 mg/L vs 175.7 mg/L, P = .02) and larger subperiosteal abscess (14 mm vs 21 mm, P < .01). Medical management was also more intensive in the OLST Fusobacterium group than in the OLST other bacteria group: increased number of conservative surgeries (66.7% vs 92.9%, P = .03) and longer hospital stay (13.7 days vs 19.8 days, P = .02). At the end of follow-up, the clinical course was good in both groups without any neurological sequelae., Conclusions: Thrombotic complications are very frequent in case of Fusobacterium mastoiditis and clinicians should be aware of the initial severity of the clinical presentation. Under appropriate management, the clinical course of Fusobacterium OLST is as good as that of other bacterial otogenic thrombosis., (© 2019 John Wiley & Sons Ltd.)

Objective: Peritonsillar abscess (PTA) is a common infectious complication of pharyngeal infection managed by otolaryngologists and emergency room physicians. Streptococcus and Fusobacterium (e.g., Fusobacterium necrophorum, FN) species are commonly isolated pathogens. The aim of this study was to determine the implication of culture results on abscess recurrence following drainage., Methods: Single-institution retrospective review of patients treated at the University of Michigan between 2000 and 2017. Demographic and clinical outcome data were analyzed, including treatment details, culture data, and recurrence., Results: One hundred fifty-six of the 990 patients in our study developed recurrence of their abscess (16%). The age ranges most susceptible to recurrence included adolescent (22.9%) and young adult groups (17.1%). Recurrent patients were more likely to have experienced acute progression of symptoms (79% vs. 71%, P = 0.03), trismus (67% vs. 55%, P = 0.006), voice changes (65% vs. 57%, P = 0.04), and dysphagia (72% vs. 61%, P = 0.01) compared to nonrecurrent patients. They were also more likely to have clinical lymphadenopathy noted on initial examination (67% vs. 56%, P = 0.009). Culture data was sent for 852 patients (86%). The presence of FN was significantly more prevalent in the recurrent group (P < 0.0001)., Conclusion: There is a high observed prevalence of FN species within PTA aspirates in the recurrent PTA population. PTA aspirate should be sent for anaerobic growth to screen for Fusobacterium species. In addition, follow-up and lower threshold for subsequent tonsillectomy should be considered in this at-risk group., Level of Evidence: 3 Laryngoscope, 129:1567-1571, 2019., (© 2018 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective and Importance: Lemierre's syndrome (LS) is a rare condition that typically starts with a bacterial oropharyngeal infection complicated by a thrombophlebitis of the internal jugular vein and septic emboli to the lungs or other organs. The most common organism isolated is Fusobacterium necrophorum, although other causative organisms are isolated in rare cases., Case Presentation: We discuss a case of LS in a 44-year-old, previously healthy man presenting with an oropharyngeal infection. F. necrophorum was isolated from blood cultures and Computed tomography of the chest demonstrated septic emboli in the lungs. Magnetic resonance imaging showed a thrombophlebitis of the sigmoid and transverse vein with continuity to the internal jugular vein., Methods: Case report and literature review., Results: F. necrophorum isolates show in vitro susceptibility to metronidazole, clindamycin, beta-lactam/beta-lactamase inhibitor combinations and carbapenems with no signs of resistance or reduced sensitivity. Anticoagulation is believed to play a favourable role in recovery of the disease because of the potential for faster resolution of thrombophlebitis and bacteraemia. Conflicting results exist in literature with many studies or reviews indicating a favourable outcome both with and without anticoagulation. Anticoagulation for LS consists in most cases of Warfarin or Low molecular weight heparins, with the last being the first choice in children. Indications for the use of anticoagulation in literature are significant clot burden, complication of septic emboli, arterial ischemic stroke, poor response to antibiotics, thrombophilia and cerebral infarction., Conclusions: Antibiotics are considered the mainstay of treatment, although statistically valid trials to evaluate optimal treatment regimens have not yet been conducted due to the low incidence of the infection. The use of anticoagulation in LS is still heavily debated as a result of conflicting results in literature. Due to the disease's low incidence, statistically valid trials that evaluate anticoagulation are lacking. Further prospective and randomized research is needed to establish the benefit of anticoagulation in the treatment of LS.

Fusobacterium necrophorum is a Gram negative, rod-shaped and aero tolerant anaerobe. In animals, it is an opportunistic pathogen frequently associated with necrotic infections, generally called necrobacillosis, such as calf diphtheria, foot rot and liver abscesses in cattle. Two subspecies exist: subsp. necrophorum and subsp. funduliforme. Among several virulence factors, leukotoxin (Lkt) is considered to be a major factor and a protective antigen. The objective of the study was to utilize BL3 cells and measure the release of lactic dehydrogenase to quantify Lkt activity of F. necrophorum. The assay was used to examine the effects of storage and handling conditions, growth media, polymyxin B addition on the cytotoxicity and evaluate Lkt activities of F. necrophorum strains isolated from bovine liver abscesses and foot rot. The Lkt activity peaked at 9 h of incubation. There was a significant decrease in the cytotoxicity measured in the samples after each freeze and thaw cycle. No difference was observed in the cytotoxicity for the samples handled aerobically versus anaerobically. Lkt activities of strains grown in anaerobic Brain-Heart Infusion broth were higher compared to Vegitone broth. A small reduction in the cytotoxicity activity was observed after the addition of polymyxin. The Lkt activity was consistently higher in strains of subsp. necrophorum than subsp. funduliforme of liver abscess origin. Among the strains isolated from cattle foot rot, Lkt activities of subsp. necrophorum strains appear to be much more variable. Use of BL3 cells in combination of lactic acid dehydrogenase assay appears to be a simple and valid assay to measure Lkt activity of F. necrophorum., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Recent reports have reported an increase in the incidence of acute mastoiditis because of Fusobacterium necrophorum. However, the crude incidence and the specific clinical and laboratory characteristics of F. necrophorum mastoiditis in children have not been described. Our aim was to describe these features to identify high-risk patients., Methods: The electronic medical records of all children with acute mastoiditis at a tertiary medical center between July 2011 and December 2015 were analyzed. Using a stepwise logistic regression to identify independent risk factors for F. necrophorum, we formulated a predictive model., Results: F. necrophorum was identified in 13% (19/149) of mastoiditis cases with an identifiable agent. Its incidence increased 7-fold from 2.8% in 2012 to 20.4% in 2015 (P = 0.02). F. necrophorum infection had unique clinical, laboratory and prognostic features. The vast majority had complications and underwent surgical intervention. The predictive model used 4 parameters to define high-risk patients for F. necrophorum infection at admission: females, winter/spring season, prior antibiotic treatment and a C-reactive protein value >20 mg/dL (area under receiver operating characteristic curve 0.929)., Conclusions: Clinicians should be aware of the increasing incidence of F. necrophorum mastoiditis and consider anaerobic cultures and specific anaerobic coverage in high-risk patients.

Fusobacterium species are components of the normal microbiota of the oral cavity, gastrointestinal tract, and female genital tract. They are increasingly recognized as causative agents of oral, laryngeal, and tonsillar infections. Several fusobacterial species are involved in infections, with F. necrophorum and F. nucleatum being the most commonly cultured subtypes. In this study, we aimed to investigate clinical and prognostic differences in terms of mortality and association with malignancy between F. necrophorum and F. nucleatum detected by culture and 16S rRNA gene sequencing. This is a systematic, comparative, retrospective, non-interventional study. Data were extracted from the Department of Clinical Microbiology, Region Zealand, Denmark: all patients with F. necrophorum or F. nucleatum detected by culture or 16S rRNA gene sequencing from 1st of January 2010 to 30th of June 2015 were included. In total, F. necrophorum was detected in samples from 75 patients, and F. nucleatum in samples from 68 patients (total: n = 143). Thirteen patients had a current cancer diagnosis at the time of fusobacterial sampling. Multivariate analyses revealed a significant association of "current cancer" with 30-day mortality. Fusobacterial subtype was not associated with mortality neither in overall nor in subgroups with or without current cancer. Despite differences in clinical disease pattern between F. necrophorum and F. nucleatum, mortality was unaffected by fusobacterial subtype. Mortality was significantly related to comorbidity, especially a current diagnosis of cancer. Our data highlights the current debate whether fusobacterial involvement in cancer may have disease-altering properties, rather than being opportunistic pathogens secondary to cancer disease.

Fusobacterium necrophorum has recently been suggested to be associated with tonsillopharyngitis, peritonsillar abscess, and recurrent tonsillitis. Between the 2 subspecies of F. necrophorum, subsp. funduliforme is known to be a major human pathogen. To better understand the epidemiology of F. necrophorum subsp. funduliforme (FNSF), we studied the prevalence of FNSF in the tonsils of patients undergoing elective tonsillectomy (TE) for different indications. Adult patients who underwent elective TE from October 2014 to November 2015 were included. The tonsils were sent for aerobic and anaerobic tissue culture within 30 min of excision; the presence of FNSF was detected using PCR with gyrB primers and 16S rRNA. A total of 32 patients were enrolled. The prevalence of FNSF identified by either culture or gyrB PCR did not significantly differ between infectious and noninfectious TE indications. The constant presence of FNSF might not be associated with recurrent pharyngotonsillitis.

The objective of this study was to determine the prevalence and identification of leukotoxin gene, lktA, variant strains of Fusobacterium necrophorum in the footrot lesions of sheep. The detection of F. necrophorum was carried out by PCR targeting the lktA gene fragment and identification of lktA variant strains was done by PCR-single stranded conformational polymorphism (PCR-SSCP) and gene sequencing. Of the 450 swabs collected from footrot lesions of sheep, 117 were lktA-positive for F. necrophorum. Of the 50 swabs collected from apparently asymptomatic sheep, only one was lktA-positive for F. necrophorum. The overall prevalence of F. necrophorum in footrot affected sheep in Kashmir valley was 26%, and ranged from 20 to 34.8%, respectively. PCR-SSCP of lktA gene fragment analysis revealed three lktA variants, designated as JKS-F1/F2/F3, while two samples (1.7%) showed multiple lktA variant strains of F. necrophorum in a single footrot-affected sheep hoof. This appears to be the first report on the presence of more than one lktA variant of F. necrophorum in a footrot lesion of sheep. The JKS-F3 lktA variant was the most frequent (75.4%), followed by JKS-F2 (14.4%) and JKS-F1 (8.4%), respectively. Among the three lktA variants identified, JKS-F3 was detected in 74 (86.0%) samples from severe footrot affected sheep with a lesion score of 4. The data suggest that JKS-F3 is the predominant lktA variant of F. necrophorum and is associated with severe footrot in sheep. Hence, JKS-F3 may be a significant variant contributing to the severity and duration of the disease in sheep., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fusobacterium necrophorum is associated with various diseases in humans and animals. Reservoirs (sites where the pathogen persists in the absence of disease) of F. necrophorum are believed to be present in healthy individuals e.g. tonsillar epithelium, or their environment e.g. soil, but for most diseases the reservoir sites are unknown. Strain typing of F. necrophorum would facilitate linking specific reservoirs with a specific disease. The aim of this study was to develop multiple locus variable number tandem repeat analysis (MLVA) as a strain typing technique for F. necrophorum, and to test the use of this scheme to analyse both isolates and mixed communities of bacteria. Seventy-three tandem repeat regions were identified in the F. necrophorum genome; three of these loci were suitable and developed as a MLVA scheme. The MLVA scheme was sensitive, specific, and discriminatory for both isolates and communities of F. necrophorum. The MLVA scheme strain typed 46/52F. necrophorum isolates including isolates of both subspecies and from different countries, host species and sample sites within host. There were 12 unique MLVA strain types that clustered by subspecies. The MLVA scheme characterised the F. necrophorum community in DNA from 32/49 foot- and 28/33 mouth swabs from sheep. There were 17 community types in total. In 31/32 foot swabs, single strains of F. necrophorum were detected while in the 28 mouth swabs there were up to a maximum of 8 strains of F. necrophorum detected. The results demonstrate the potential for this method to elucidate reservoirs of F. necrophorum., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Infectious suppurative thrombophlebitis of the portal venous system, referred to as pylephlebitis, is a rare complication of intra-abdominal inflammatory processes. Advances in diagnostics and antibiotics have improved survival, but mortality remains remarkably high even in the most recent literature. The majority of patients have concomitant bacteraemia on presentation most commonly with typical gastrointestinal (GI) organisms. On rare occasion, patients have culture positive Fusobacterium , which has recently been associated with occult GI and genitourinary malignancies. Here, we describe a patient presenting with pylephlebitis and Fusobacterium bacteraemia who responded well to medical therapy, review pertinent literature and discuss the benefits of screening endoscopy in this patient population., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Fusobacterium necrophorum is the oropharyngeal pathogen usually associated with Lemierre's syndrome, a pharyngeal infection which evolves to sepsis, septic emboli and thrombophlebitis of the adjacent neck vessels. It is an uncommon causative bacteria of a liver abscess, and an extensive workup should, therefore, be performed in order to rule out potential sources of the infection. This case report describes the workup that led to the diagnosis of a colorectal carcinoma, which was deemed to be the source of the Fusobacterium bacteraemia., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Leukotoxin is a well-known virulence factor of animal isolates of Fusobacterium necrophorum subspecies necrophorum, and is also expressed by animal isolates of subspecies funduliforme, whereas its presence in isolates from humans has not been fully established. In this study we found that the leukotoxin gene was present in all tested F. necrophorum isolates from humans. Three sequence variants were found, two of which have not been described previously. The sequence types correlated to source of infection. Further studies are needed to examine the role of the leukotoxin in human infections., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Fusobacterium necrophorum , an obligate anaerobic bacterium, was recently reported to be an important cause of bacterial pharyngitis with a prevalence as high as that of group A Streptococcus (GAS) in adolescents and young adults. Importantly, F. necrophorum is the primary causative agent of the life-threatening Lemierre's syndrome, and screening of pharyngeal samples may be warranted for its early detection and prevention. The aim of this study was to determine the prevalences of F. necrophorum and groups A and C/G streptococci as agents of bacterial pharyngitis in children. Pharyngeal samples ( n = 300) were collected from pediatric patients presenting to the emergency department with signs and symptoms of pharyngitis. Overall, 10 (3.3%), 79 (26.3%), and 4 (1.3%) patients were PCR positive for F. necrophorum , GAS, and group C/G streptococci, respectively. The prevalence of F. necrophorum was significantly higher in patients between the ages of 14 and 20 years at 13.5% than in patients aged 14 years and younger (1.9%, P < 0.001). All positive patients presented with signs and symptoms similar to GAS pharyngitis. Our data demonstrated a potential role for F. necrophorum as a pathogen of pharyngitis among young adults, but suggests that the prevalence of F. necrophorum is low in preadolescent patients., (Copyright © 2017 American Society for Microbiology.)

Case Presentation: A 19-year-old previously healthy man presented, minimally responsive, in respiratory distress to an ED after a 2-week history of headache, photophobia, and neck stiffness. Associated symptoms included low-grade fevers, malaise, and dark urine. He had no recent travel, ill contacts, consumption of undercooked meat, new sexual contacts, or illicit drug use. The patient resided in a campus dormitory and did not consume alcohol or tobacco., (Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to review the current evidence for an association between Fusobacterium necrophorum (FN) and acute tonsillitis (AT), to assess the prevalence of FN in AT, to identify the better FN detection method, and to characterize the clinical characteristics of FN-positive patients with uncomplicated AT. A systematic literature search was conducted in the PubMed, EMBASE, and SweMed+ databases for studies reporting on the recovery rates of FN in patients with AT. A total of 498 unique records were identified. Eleven studies were included in a qualitative synthesis and six studies were included in a meta-analysis. Considerable heterogeneity (I 2 = 60 %) and risk of bias and confounders was found among the studies, though a subset of studies (prospective) had lower heterogeneity and higher study quality. FN was recovered significantly more frequently from patients (21.2 %) compared to healthy controls (7.6 %) (p < 0.001). FN recovery rates were similar between culture-based studies (20.3 %) and studies using polymerase chain reaction (PCR) methodology (22.2 %) (p = 0.462). The typical FN-positive AT patient was a smoking young (15-25 years) male presenting with tonsillar exudates and a Centor score of 2 or higher. A clear association between FN and AT was found. FN is likely to be a significant and prevalent pathogen in AT, especially in teenagers and young adults. However, no evidence for causality between FN and AT has been established and it is unexplored if timely antibiotic therapy directed against FN accelerates the resolution of symptoms and decreases the risk of complications.

Fusobacterium necrophorum findings in Denmark and estimation of the incidence of F. necrophorum bacteraemia was described using data from the nationwide Danish microbiology database (MiBa). All microbiological reports on any Fusobacterium species in Denmark were extracted for a period of 5 years from 2010 to 2014 from MiBa and from the local department of clinical microbiology. The overall incidence of F. necrophorum bacteraemia from 2010 to 2014 was 2.8 cases per million/year vs 9.4 in the age group 15-24 years. F. necrophorum was rare in blood cultures from children and middle-aged patients and then raised again. However, 48 of 232 cases of Fusobacterium bacteraemia were not identified to species level, so the incidences of F. necrophorum bacteraemia may be underestimated in our study. F. necrophorum was found in throat swabs in the age group between 13 and 40 years and in otitis media in children below 2 years in those departments which performed anaerobic culture. The incidence of F. necrophorum bacteraemia found was comparable to earlier reported figures for Lemierre's syndrome. Fusobacterium bacteraemia should always be identified to species level., (© 2016 APMIS. Published by John Wiley & Sons Ltd.)

Fusobacteria belong to the normal population of the pharyngeal mucosa as well as the mucosa of the upper airways and the gastrointestinal tract. Infections are comparatively rare. The most common causative organism is Fusobacterium necrophorum. A well-known infection caused by this germ is Lemierre's syndrome. In the presented case, a 19-year-old man (123 kg body weight, 186 cm body length) was found dead in his bed in the morning after having complained of muscular fatigue and vomiting the previous day. Autopsy was carried out only two days after death. At that time, the body showed marked putrefaction with partial greenish discoloration and marbling of the skin although it had been stored in a refrigerator at +2 degrees C in the meantime. While the autopsy itself revealed no cause of death, microbiological examination of a smear from the left lower pulmonary lobe demonstrated Staphylococcus aureus and Fusobacterium necrophorum. Toxicological investigations produced negative results throughout. The cause of death was defined as sepsis caused by Fusobacterium necrophorum.

There is an increased recovery of Fusobacterium necrophorum from cases of otitis media and mastoiditis in the pediatric population. These infections may be highly severe, causing local osteomyelitis, bacteremia, and Lemierre's syndrome. The severity and difficulties in providing optimal treatment for these infections may be especially difficult in this age group due to immunological immaturity and delayed presentation. In this review of literature, we present and analyze the clinical presentation, management, and outcome of otic infections caused by F. necrophorum in infants and young toddlers less than 2 years old. Search in Pubmed was conducted for reported cases in the English literature for the time period of the last 50 years. Twelve well-described cases were retrieved with F. necrophorum otitis and mastoiditis and complications reported in all cases. Treatment included both intravenously with antimicrobial agents (beta lactams plus metronidazole) and mastoidectomy. Lemierre's syndrome and Lemierre's syndrome variants developed in 60 % of the patients. Dissemination of the infection as distal osteomyelitis and septic shock were also reported. The outcome was favorable in all the cases. Otitis and mastoiditis infections in children less then 2 years old are invasive infections, and severe complications can occur.

Purpose: This study aimed at reviewing our experience with infections caused by Fusobacterium in children., Methods: A retrospective analysis of medical records of children admitted to Hadassah-Hebrew University Medical Center from 2000 to 2013, in whom Fusobacterium spp. was identified in any specimen., Results: A total of 22 patients (males = 12) at a mean ± SE age of 5 ± 1 (range 1-17) years, were identified. The most common complication was abscess formation (n = 11, 50 %). Eight children (36.4 %) had intracranial complications, including brain abscess (n = 4), meningitis (n = 4) and cerebral sinus vein thrombosis (CSVT, n = 5). Seventeen children (77 %) had bacteremia. Primary site of infection was otogenic (n = 9), oropharyngeal (n = 7), respiratory (n = 2), sinuses (n = 2), intra-abdominal (n = 1) and mucositis (n = 1). Fourteen cases were caused by Fusobacterium necrophorum, including four cases with CSVT, 7/8 cases of mastoiditis, four of them with subperiosteal abscess formation; all four cases with meningitis and two brain abscesses. Fifteen (68 %) patients required surgical intervention and 3 (14 %) received anti-coagulation therapy. Excluding one patient with overwhelming sepsis with fatal outcome, all patients recovered., Conclusions: Fusobacterium infections in children can cause a diverse spectrum of disease and is associated with high rates of abscess formation and intracranial complications. Although Fusobacterium nucleatum is abundant in the oral cavity, F. necrophorum is the main pathogen that causes severe infections in healthy children.

The aim of this study was to determine the proportion of Dichelobacter nodosus, Fusobacterium necrophorum and Treponema spp. in sheep with different clinical manifestations of footrot compared to healthy sheep both at flock and individual level. The second aim was to characterise D. nodosus with respect to virulence, presence of intA gene and the serogroups. Swab samples (n=1000) from footrot-affected (n=10) and healthy flocks (n=10) were analysed for the presence of D. nodosus, F. necrophorum and Treponema spp. by real-time PCR and culturing (D. nodosus only). Dichelobacter nodosus isolates (n=78) and positive swabs (n=474) were analysed by real-time PCR for the aprV2/B2 and the intA genes and by PCR for the fimA gene (isolates only). D. nodosus was more commonly found in flocks affected with footrot than in clinically healthy flocks. A significant association was found between feet with severe footrot lesions and the aprV2 gene and between feet with moderate or no lesions and the aprB2 gene, respectively. F. necrophorum was more commonly found in flocks with footrot lesions than in flocks without lesions. No significant association was found between sheep flocks affected with footrot and findings of Treponema spp. or the intA gene. Benign D. nodosus of six different serogroups was detected in twelve flocks and virulent D. nodosus of serogroup G in one. In conclusion, D. nodosus and F. necrophorum were more commonly found in feet with footrot than in healthy feet. The majority of D. nodosus detected was benign, while virulent D. nodosus was only detected in a single flock., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Fusobacterium necrophorum is a well-known cause of Lemirre's disease and accumulating evidence support its pathogenic role in peritonsillar abscess while its role in recurrent and chronic tonsillitis is uncertain. The objective of this study was to assess the prevalence of oropharyngeal colonisation with F. necrophorum and Beta-haemolytic streptococci in a cohort of patients scheduled for tonsillectomy due to recurrent or persistent throat pain, and to evaluate the dynamics of colonisation with repeated sampling during a follow-up time of 6 to 8 months., Methods: Fifty-seven (57) patients aged 15-52 years scheduled for tonsillectomy due to chronic/recurrent tonsillitis or recurrent peritonsillar abscess were included. Throat swabs for the detection of F. necrophorum and Beta-haemolytic streptococci and clinical data was collected at inclusion, at the time of surgery and 6 to 8 months after surgery. Statistical analysis was performed using the Chi-square, Fisher's exact and Mc Nemar tests., Results: Fusobacterium necrophorum was found in 28, 30 and 16% of the patients at inclusion, surgery and follow up respectively. The corresponding results for beta-haemolytic streptococci were 5, 9 and 5%. Patients colonised with F. necrophorum at follow-up, after tonsillectomy, were equally relieved from their previous throat pain as non-colonised patients. Looking at individual patients, the culture results for F. necrophorum varied over time, indicating a transient colonisation., Conclusion: Fusobacterium necrophorum was frequently found in throat cultures in this cohort of patients with recurrent or chronic throat pain leading to tonsillectomy. Colonisation was equally frequent in the asymptomatic cohort post-tonsillectomy, indicating that F. necrophorum is not alone causative of the symptoms. In an individual perspective, colonisation with F. necrophorum was transient over time.

Fusobacterium necrophorum, a Gram-negative anaerobe, is the primary etiologic agent of liver abscesses in cattle. There are two subspecies; subsp. necrophorum and subsp. funduliforme, which differ in morphological, biochemical, molecular characteristics, and virulence. The subsp. necrophorum, which is more virulent, occurs more frequently in liver abscesses than the subsp. funduliforme. Bacterial adhesion to the host cell surface is critical to the pathogenesis of several bacterial infections, and in F. necrophorum, outer membrane proteins (OMP) have been shown to mediate adhesion to bovine endothelial cells. The objective of this study was to identify potential adhesins that are involved in adhesion of F. necrophorum subsp. necrophorum to the host cells. An OMP of 42.4 kDa, which binds with high affinity to the bovine endothelial cells and is recognized by the sera from cattle with liver abscesses, was identified. N-terminal sequencing of the protein showed 96% homology to the FomA protein of F. nucleatum. The PCR analysis showed that this fomA gene was present in several strains of subsp. necrophorum, subsp. funduliforme of bovine and subsp. funduliforme of human origin. The purified native and recombinantly expressed protein when preincubated with the endothelial cells, prevented the attachment of subsp. necrophorum significantly. In addition, the polyclonal antibody produced against the protein prevented the binding of subsp. necrophorum to bovine endothelial cells., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The role of Fusobacterium necrophorum in tonsillitis in adolescents and young adults was retrospectively investigated by culture examination. We compared the prevalence of F. necrophorum in 212 subjects with confirmed clinical tonsillitis and in 176 subjects with confirmed no clinical tonsillitis. The prevalence of F. necrophorum was significantly higher (p < 0.001) in subjects with clinical tonsillitis (27%) compared to subjects with no clinical tonsillitis (6%). These results clearly demonstrate the role of F. necrophorum in tonsillitis. By diagnosing and treating F. necrophorum tonsillitis with, for example, penicillin, metronidazole, or both, we might prevent some cases of Lemierre syndrome., (Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

The injection of drugs into the neck is unusual and thrombosis of the internal jugular vein can be a rare clinical presentation with a high risk for severe complications. We report a case of a 31-year-old male intravenous drug user presenting with fever, shortness of breath and right neck oedema. Laboratory studies revealed elevated inflammation parameters. X-ray imaging revealed a broken syringe needle inside the soft tissues of the neck. Computed tomography (CT) scans of the thorax and brain were unremarkable, while cervical CT showed a fully thrombosed, right internal jugular vein. Intravenous antibiotics were initiated, and modified after identification of an anaerobic Gram-negative oropharynx-derived pathogen (Fusobacterium necrophorum). The patient was discharged after resolution of symptoms under treatment. Septic internal jugular vein thrombosis should always be included in the differential diagnosis of local neck inflammation and systemic sepsis in intravenous drug users. Prompt and aggressive antibiotic treatment is vital, whereas the role of anticoagulation therapy is not definitely known.

Gradenigo's syndrome is a rare but life threatening complication of acute otitis media (AOM), which includes a classic triad of otitis media, deep facial pain and ipsilateral abducens nerve paralysis. The incidence of Fusobacterium necrophorum infections has increased in recent years. We describe two cases of Gradenigo's syndrome caused by F. necrophorum. Additional four cases were identified in a review of the literature. Gradenigo's syndrome as well as other neurologic complications should be considered in cases of complicated acute otitis media. F. necrophorum should be empirically treated while awaiting culture results., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Anaerobic bacterial infection is often accompanied by abscess formation; however, few in vivo studies have been published with descriptive data specifically evaluating antimicrobial activity in the presence of abscesses. The aim of this study was to establish a murine model of anaerobic infection with abscess formation and to verify the utility of this model for evaluating the in vivo efficacy of an antimicrobial agent. A clinical isolate of Fusobacterium necrophorum was inoculated into the caudal vein of immunocompetent BALB/c mice at 10(8) c.f.u. per mouse. Changes in body weight, bacterial load and histopathology of key organs were evaluated. After inoculation, bacterial counts in the liver increased from 10(4) to 10(8) c.f.u. after 1-3 days, and liver abscess formation was observed on the day following infection. Abscess formation and bacterial growth were not observed in other organs. In this model, 3 days of treatment with 5 mg metronidazole kg(-1) eradicated F. necrophorum in the liver; however, a reduction in bacterial load was not observed with 0.05 mg metronidazole kg(-1). In this study, we established a novel murine model of F. necrophorum liver abscess via haematogenous infection that may be useful for investigating in vivo antimicrobial activity against anaerobic abscesses and understanding the pathogenesis of F. necrophorum infection.

We report the case of a 71-year-old woman who presented a primary spinal epidural abscess caused by Fusobacterium necrophorum. This is the second report in the medical literature to associate this organism with a primary spinal epidural abscess without spondylodiscitis. After treatment with emergency laminectomy followed by 8 weeks of antibiotic treatment the patient was cured. Oral metronidazole (500 mg every 8 h) was the definitive choice of treatment. F. necrophorum spinal epidural abscess is rare, although samples for anaerobic culture should be collected in order to improve detection of anaerobic spinal infections. PCR amplification and sequencing of the 16S rRNA permits early diagnosis in anaerobic infections., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In the present case a 30-year-old African American man was admitted with fever and chills secondary to two large hepatic abscesses diagnosed on an ultrasound. The patient was started on antibiotics after blood cultures were drawn. Initially the abscess was drained and showed dramatic improvement upon repeat imaging. The blood cultures revealed Gram-negative rods that were identified as Fusobacterium necrophorum. At that time the patient was switched to levofloxacin and metronidazole based on sensitivities. On this new antibiotic regime the patient improved dramatically. After just 5 days the patient was discharged home on oral antibiotics and was scheduled to follow-up in 1 week. In the present case we present a healthy 30-year-old man with no significant co-morbidities who developed a hepatic abscess from F necrophorum but successfully recovered after appropriate antibiotic treatment.

Severe oropharyngeal infection can result in Lemierre's disease, a syndrome with high mortality secondary to inflammation and thrombosis of cervical and intracranial veins with involvement of contiguous structures; however arterial involvement is rare. We report a case of Lemierre's disease in a 12 year old boy with severe narrowing of the left cavernous carotid artery., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Fusobacterium necrophorum, a Gram-negative, anaerobic bacterium, is an opportunistic animal and human pathogen that causes a variety of infections termed necrobacillosis. There are 2 subspecies of F. necrophorum (subsp. necrophorum and subsp. funduliforme) that differ morphologically and biochemically and in virulence. Leukotoxin, a secreted protein, is considered to be the major virulence factor. In camelids, F. necrophorum causes a variety of infections, generally involving the lips, tongue, pharynx, interdigital spaces, foot pad, larynx, mandible, or maxillary bones. The objective of the current study was to characterize the presumptive Fusobacterium isolates from a variety of necrotic infections in llama (Lama glama) and alpaca (Vicugna pacos) and determine whether the strains possess leukotoxin activities. A total of 7 isolates from alpaca and 2 isolates from llama were characterized. Based on growth characteristics in broth culture, and biochemical and polymerase chain reaction analyses, all 9 isolates belonged to subsp. necrophorum and possessed the putative hemagglutinin gene. Western blot analysis with antileukotoxin antibodies raised in rabbit showed the presence of leukotoxin protein in the culture supernatant of all isolates. Furthermore, flow cytometry of the culture supernatants demonstrated cytotoxicity to bovine and alpaca polymorphonuclear leukocytes (PMNs). The extent of cytotoxicity to either alpaca or bovine PMNs differed among camelid strains. The cytotoxicity of many of the camelid strains was higher (P < 0.05) toward alpaca PMNs compared to bovine PMNs. Fusobacterium necrophorum isolates from llama and alpaca are similar to bovine isolates, and leukotoxin may be a major virulence factor.

Periodontal diseases (PD) are diseases of polymicrobial aetiology and constitute major health problems in captive macropods. Increasing knowledge of the causal pathogens is therefore crucial for effective management and prevention of these diseases. PCR survey and sequence analyses of potential periodontopathogens in captive wallaby populations revealed a co-incidence of the diseases with the detection of Fusobacterium necrophorum subsp. necrophorum (Fnn) and its encoded leukotoxin (lktA) gene. Sequence analyses showed that the outer membrane protein of Fnn in the GenBank database shared significant homology (99%) with the Fnn encoded haemagglutinin-related-protein gene fragment identified in this study. In addition, this report suggests the existence of a variant of Fnn with no detectable lktA gene and thus warrants further studies. In contrast to reports associating Porphyromonas gingivalis and F. nucleatum with PD, this study revealed that PD in macropods are associated with Porphyromonas gulae and Fnn and raises the question: is there a possible host pathogen co-evolution in the pathogenesis of PD in animals and humans? These findings contribute to the understanding of the aetiology of periodontal disease in macropods as well as opening up a new direction of research into the microbial interactions involved in the pathogenesis of PD in macropods., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Fusobacterium necrophorum, a Gram-negative anaerobe, is frequently associated with suppurative and necrotic infections of animals and humans. The organism is a major bovine pathogen, and in cattle, the common fusobacterial infections are hepatic abscesses, foot rot, and necrotic laryngitis. The species comprises two subspecies: F. necrophorum subsp. necrophorum and F. necrophorum subsp. funduliforme. Bacterial adhesion to the host cell surface is a critical initial step in the pathogenesis, and outer membrane proteins (OMP) play an important role in adhesion and establishment of certain Gram-negative bacterial infections. The means by which F. necrophorum attaches to epithelial or endothelial cells has not been determined. We evaluated whether OMP of F. necrophorum, isolated from a liver abscess, mediated adhesion to bovine endothelial cells (adrenal gland capillary endothelial cell line). The extent of binding of subsp. necrophorum to the endothelial cells was higher than that of F. necrophorum subsp. funduliforme. Trypsin treatment of bacterial cells decreased their binding to endothelial cells indicating the protein nature of adhesins. Preincubation of endothelial cells with OMP extracted from F. necrophorum decreased the binding of bacterial cells. In addition, binding of each subspecies to endothelial cells was inhibited by polyclonal antibodies raised against respective OMP and the antibody-mediated inhibition was subspecies specific. The western blot analysis of OMP bound to endothelial cells with anti-OMP antibodies showed four OMP of 17, 24, 40 and 74 kDa. We conclude that OMP of F. necrophorum play a role in adhesion of bacterial cells to the endothelial cells., (Copyright © 2012 Elsevier B.V. All rights reserved.)