Should the risk of Fusobacterium necrophorum pharyngotonsillitis influence prescribing empiric antibiotics for sore throats in adolescents and young adults?

Fusobacterium necrophorum, a gram-negative anaerobe, causes pharyngotonsillitis primarily in adolescents and young adults (approximately 15-30 years old). The same age group has the highest incidence of peritonsillar abscess and the Lemierre syndrome. The same organism, F. necrophorum, is the most common cause of peritonsillar abscess in this age group and causes at least 80% of Lemierre syndrome cases. We outline the case for empiric antibiotic treatment of some patient in this age group who have a significant probability that F. necrophorum is the cause of their pharyngotonsillitis.

Bactericidal activity of hexylresorcinol lozenges against oropharyngeal organisms associated with acute sore throat.

OBJECTIVE: For the majority of people with acute sore throat, over-the-counter treatments represent the primary option for symptomatic relief. This study evaluated the in vitro bactericidal activity of lozenges containing the antiseptic hexylresorcinol against five bacteria associated with acute sore throat: Staphylococcus aureus, Streptococcus pyogenes, Moraxella catarrhalis, Haemophilus influenzae and Fusobacterium necrophorum. RESULTS: Hexylresorcinol 2.4 mg lozenges were dissolved into 5 mL of artificial saliva medium. Inoculum cultures were prepared in triplicate for each test organism to give an approximate population of 108 colony-forming units (cfu)/mL. Bactericidal activity was measured by log reduction in cfu. Greater than 3log10 reductions in cfu were observed at 1 min after dissolved hexylresorcinol lozenges were added to S. aureus (log10 reduction cfu/mL ± standard deviation, 3.3 ± 0.2), M. catarrhalis (4.7 ± 0.4), H. influenzae (5.8 ± 0.4) and F. necrophorum (4.5 ± 0.2) and by 5 min for S. pyogenes (4.3 ± 0.4). Hexylresorcinol lozenges achieved a > 99.9% reduction in cfu against all tested organisms within 5 min, which is consistent with the duration for a lozenge to dissolve in the mouth. In conclusion, in vitro data indicate that hexylresorcinol lozenges offer rapid bactericidal activity against organisms implicated in acute sore throat.

Characterization of Fusobacterium necrophorum subsp. necrophorum outer membrane proteins.

Liver abscesses are of major economic importance to the cattle industry. These are mainly associated with the presence of Fusobacterium necrophorum, a non-spore forming and Gram-negative anaerobe. There are two main subspecies, F. necrophorum subspecies necrophorum and subsp. funduliforme, and they differ molecularly, morphologically, biochemically and in virulence. Previous studies have shown that the outer membrane proteins (OMP) of F. necrophorum subsp. necrophorum are important for its successful binding to immobilized bovine adrenal gland capillary endothelial (EJG) cells. In this study, a 42.4 kDa OMP of F. necrophorum subsp. necrophorum with the highest binding capacity to EJG cells was characterized. The gene was cloned into pFLAG-CTS vector and the proteins were subsequently expressed on the surface of E. coli BL21 DE3 cells. When E. coli carrying the recombinant plasmid (SM 2013) was induced using IPTG, there was significant enhancement in the binding to immobilized EJG cells compared to both uninduced SM 2013 and the E. coli carrying control vector only. When fixed EJG cells were incubated with purified native OMP, SM 2013 showed lowered levels of binding, compared to the uninduced SM 2013 and the E. coli carrying control vector only. Pre-incubation of induced SM 2013 with polyclonal antibodies made against the OMP reduced the binding to immobilized EJG cells to uninduced SM 2013 levels. This gain of function by recombinant E. coli confirms the ability of this protein to act as an adhesion to help binding of F. necrophorum subsp. necrophorum to host cells.

Analysis of the tonsillar microbiome in young adults with sore throat reveals a high relative abundance of Fusobacterium necrophorum with low diversity.

Fusobacterium necrophorum (Fn), a gram-negative anaerobe, is increasingly implicated as an etiologic agent in older adolescents and young adults with sore throat. Inadequately treated Fn pharyngitis may result in suppurative complications such as peritonsillar abscess and Lemierre's syndrome. Data from the literature suggest that the incidence of life-threating complications in these age groups from Fn pharyngitis (Lemierre's syndrome) in the United States exceeds those associated with group A beta-hemolytic streptococcal (GAS) pharyngitis (acute rheumatic fever). Using real-time PCR, we previously reported about a 10% prevalence of Fn in asymptomatic medical students and about 20% in students complaining of sore throat at a university student health clinic (p = 0.009). In this study, a comprehensive microbiome analysis of the same study samples confirms that Fn pharyngitis was more common than GAS pharyngitis. Eighteen patients were found to have Fn OTU values exceeding an arbitrary cutoff value of 0.1, i.e. greater than 10% of total sequences, with five subjects reaching values above 0.7. By contrast only 9 patients had GAS OTU values greater than 0.1 and none exceeded 0.6. When the data were analyzed using five separate assessments of alpha diversity, in each case for Fn there were statistically significant differences between Fn positive_high (OTU abundance > 0.1) vs control, Fn positive_high vs Fn negative (OTU abundance = 0), Fn positive_high vs Fn positive_low (OTU abundance > 0 and < 0.1). When the data were analyzed using three beta diversity indexes (Bray-Curtis, weighted unifrac, and unweighted unifrac), there were statistically significant differences between Fn positive_high (OTU abundance ≥ 0.1) vs control for all three. Statistically significant differences remained if we chose somewhat different OTU abundance cutoffs of 0.05 or 0.15. We conclude that Fn appears to play a dominant role in bacterial pharyngitis in the older adolescent and young adult age groups and that the development of a productive mucosal infection with Fn is linked to a significant decrease in the diversity of the associated tonsillar microbiome.

Pathogenesis and Treatment of Bovine Foot Rot.

Bovine foot rot (BFR) is an infectious disease of the interdigital skin and subcutaneous tissues of beef and dairy cattle that occurs under a variety of management and environmental settings. The anaerobic, gram-negative bacteria Fusobacterium necrophorum, Porphyromonas levii, and Prevotella intermedia are commonly isolated from lesions. A multitude of host, agent, and environmental factors contribute to the development of BFR. Initiation of systemic antimicrobial therapy early in the course of disease commonly leads to resolution. Delays in treatment may result in extension of infection into deeper bone, synovial structures, or ligamentous structures, and the prognosis for recovery is reduced.

Mixed species biofilms of Fusobacterium necrophorum and Porphyromonas levii impair the oxidative response of bovine neutrophils in vitro.

Biofilms composed of anaerobic bacteria can result in persistent infections and chronic inflammation. Host immune cells have difficulties clearing biofilm-related infections and this can result in tissue damage. Neutrophils are a vital component of the innate immune system and help clear biofilms. The comparative neutrophilic response to biofilms versus planktonic bacteria remains incompletely understood, particularly in the context of mixed infections. The objective of this study was to generate mixed species anaerobic bacterial biofilms composed of two opportunistic pathogens, Fusobacterium necrophorum and Porphyromonas levii, and evaluate neutrophil responses to extracellular fractions from both biofilms and planktonic cell co-cultures of the same bacteria. Purified bovine neutrophils exposed to culture supernatants from mixed species planktonic bacteria showed elevated oxidative activity compared to neutrophils exposed to biofilms composed of the same bacteria. Bacterial lipopolysaccharide plays a significant role in the stimulation of neutrophils; biofilms produced substantially more lipopolysaccharide than planktonic bacteria under these experimental conditions. Removal of lipopolysaccharide significantly reduced neutrophil oxidative response to culture supernatants of planktonic bacteria. Oxidative responses to LPS-removed biofilm supernatants and LPS-removed planktonic cell supernatants were similar. The limited neutrophil response to biofilm bacteria observed in this study supports the reduced ability of the innate immune system to eradicate biofilm-associated infections. Lipopolysaccharide is likely important in neutrophil response; however, the presence of other extracellular, immune modifying molecules in the bacterial media also appears to be important in altering neutrophil function.

The role of Fusobacterium necrophorum in pharyngotonsillitis - A review.

Fusobacterium necrophorum is a gram-negative anaerobic bacterium that is the causative agent of the invasive disease Lemierre's syndrome. In addition, it is also associated with peritonsillar abscess formation and otitis media in small children. Recent research has shown that F. necrophorum may be involved in pharyngotonsillitis especially in adolescent and young adults and that it may be the second most common bacterial cause of pharyngotonsillitis after Streptococcus pyogenes (Group A streptococci). Peritonsillar abscesses and Lemierre's syndrome due to F. necrophorum are also found in this age group, suggesting that they may be complications of F. necrophorum pharyngotonsillitis. In this review we present the present knowledge about the role of F. necrophorum in pharyngotonsillitis with special emphasis on the age distribution. We argue that F. necrophorum is an important pathogen involved in pharyngotonsillitis in the age group of 13-40 years of age and we urge clinical microbiology labs to set up the appropriate techniques to be able to detect F. necrophorum from throat swabs.

Fusobacterium necrophorum otitis and mastoiditis in infants and young toddlers.

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.

First study of pathogen load and localisation of ovine footrot using fluorescence in situ hybridisation (FISH).

Analysis of bacterial populations in situ provides insights into pathogen population dynamics and potential reservoirs for disease. Here we report a culture-independent study of ovine footrot (FR); a debilitating bacterial disease that has significant economic impact on sheep farming worldwide. Disease begins as an interdigital dermatitis (ID), which may then progress to separation of the hoof horn from the underlying epidermis causing severe footrot (SFR). Dichelobacter nodosus is the causative agent of ovine FR, however, the role of Fusobacterium necrophorum and other bacteria present in the environment and on the feet of sheep is less clear. The objective of this study was to use fluorescence in situ hybridisation (FISH) to detect, localise and quantify D. nodosus, F. necrophorum and the domain Bacteria from interdigital skin biopsies of healthy, ID- and SFR-affected feet. D. nodosus and F. necrophorum populations were restricted primarily to the epidermis, but both were detected more frequently in feet with ID or SFR than in healthy feet. D. nodosus cell counts were significantly higher in feet with ID and SFR (p<0.05) than healthy feet, whereas F. necrophorum cell counts were significantly higher only in feet with SFR (p<0.05) than healthy feet. These results, together with other published data, indicate that D. nodosus likely drives pathogenesis of footrot from initiation of ID to SFR; with D. nodosus cell counts increasing prior to onset of ID and SFR. In contrast, F. necrophorum cell counts increase after SFR onset, which may suggest an accessory role in disease pathogenesis, possibly contributing to the severity and duration of SFR.

A molecular survey of a captive wallaby population for periodontopathogens and the co-incidence of Fusobacterium necrophorum subspecies necrophorum with periodontal diseases.

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.

Adhesion of Fusobacterium necrophorum to bovine endothelial cells is mediated by outer membrane proteins.

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.

Fusobacterium necrophorum endocarditis Case report and review of the literature.

Fusobacterium necrophorum is a gram-negative anaerobic bacillus that can cause serious systemic infections typically in previously healthy young adults. Lemierre's syndrome, also known as post-anginal sepsis or necrobacillosis, is the infection most usually associated with F. necrophorum. However, F. necrophorum is also a very rare cause of anaerobic endocarditis. Mortality and rates of thromboembolism are high with F. necrophorum endocarditis. In this article, we describe a case of F. necrophorum native valve infective endocarditis. The patient was treated with penicillin plus clindamycin followed by penicillin alone for 6 weeks resulting in complete resolution of infection.

[Lemierre syndrome]. / Syndrome de Lemierre.

Lemierre's syndrome is a rare and severe condition, with a primary focus in the cervicofacial area and followed by thrombosis of the internal jugular vein and metastatic infections, most often pulmonary. The principal pathogen is Fusobacterium necrophorum. Less rare and associated with high mortality before antibiotics, Lemierre syndrome had became exceptional until the increase in the number of cases in recent years. Recovery is usually the rule, but often only after long convalescence and often surgical intervention. The reemergence of this disease calls for a review of the literature to update knowledge about its epidemiologic, clinical, and therapeutic aspects.

Fusobacterium necrophorum: a ruminal bacterium that invades liver to cause abscesses in cattle.

Fusobacterium necrophorum, a Gram-negative, rod-shaped, and an aerotolerant anaerobe, is a normal inhabitant of the rumen of cattle. The organism is in ruminal contents and adherent to the ruminal wall. Its role in ruminal fermentation is to metabolize lactic acid and degrade feed and epithelial proteins. The ruminal concentration is higher in grain-fed than forage-fed cattle. From the rumen, the organism gains entry into the portal circulation and is trapped in the liver to cause abscesses. The organism is an opportunistic pathogen and a primary causative agent of liver abscesses, an economically important disease of grain-fed cattle. Liver abscesses are often secondary to ruminal acidosis and rumenitis in grain-fed cattle. Two subspecies of F. necrophorum, subsp. necrophorum (biotype A) and subsp. funduliforme (biotype B), are recognized that can be differentiated based on morphological, biochemical, biological and molecular characteristics. The subsp. necrophorum is more virulent and is isolated more frequently from infections than the subsp. funduliforme. Several toxins or secreted products have been implicated as virulence factors. The major factors contributing to ruminal colonization and invasion into the liver are hemagglutinin, endotoxin and leukotoxin, of which leukotoxin is the protective antigen. In some conditions, the organism synergistically interacts with Arcanobacterium pyogenes, a facultative anaerobic organism and a secondary etiologic agent, to cause liver abscesses.

Frequency, microbial interactions, and antimicrobial susceptibility of Fusobacterium nucleatum and Fusobacterium necrophorum isolated from primary endodontic infections.

This study assessed the prevalence and microbial interactions of Fusobacterium nucleatum and Fusobacterium necrophorum in primary endodontic infections from a Brazilian population and their antimicrobial susceptibility to some antibiotics by the E-test. One hundred ten samples from infected teeth with periapical pathologies were analyzed by culture methods. Five hundred eighty individual strains were isolated; 81.4% were strict anaerobes. F. nucleatum was found in 38 root canals and was associated with Porphyromonas gingivalis, Prevotella spp., and Eubacterium spp. F. necrophorum was found in 20 root canals and was associated with Peptostreptococcus prevotii. The simultaneous presence of F. nucleatum and F. necrophorum was not related to endodontic symptoms (p > 0.05). They were 100% susceptible to amoxicillin, amoxicillin/clavulanate, and cephaclor. Fusobacterium spp. is frequently isolated from primary-infected root canals of teeth with periapical pathologies. Amoxicillin is a useful antibiotic against F. nucleatum and F. necrophorum in endodontic infections and has been prescribed as the first choice in Brazil.

Stimulation of epithelial cell matrix metalloproteinase (MMP-2, -9, -13) and interleukin-8 secretion by fusobacteria.

BACKGROUND/AIMS: Bacterial pathogens involved in periodontal diseases exert their destructive effects primarily by stimulating the host cells to increase their secretion of proinflammatory cytokines and matrix metalloproteinases (MMPs). This study aimed to determine the epithelial cell matrix metalloproteinase and interleukin-8 (IL-8) secretion upon exposure to fusobacteria. METHODS: Eight different oral and non-oral Fusobacterium strains were incubated with HaCaT epithelial cells. Gelatin zymography and Western blot analysis were performed to detect collagenase 3 (MMP-13), gelatinase A (MMP-2), gelatinase B (MMP-9), and IL-8 secretion by epithelial cells. RESULTS: All Fusobacterium strains, especially Fusobacterium necrophorum ATCC 25286, Fusobacterium nucleatum ATCC 25586, and Fusobacterium varium ATCC 51644, increased MMP-9 and MMP-13 secretion. Fusobacterium simiae ATCC 33568, and to a lesser extent F. nucleatum and F. necrophorum, increased epithelial MMP-2 secretion. F. nucleatum and F. necrophorum also increased IL-8 secretion. F. varium ATCC 27725, a strain that only weakly stimulated MMP production, strongly increased the IL-8 production, suggesting that their expression is differently regulated. CONCLUSION: We conclude that the pathogenic potential of fusobacteria may partly result from their ability to stimulate secretion of MMP-9, MMP-13, and IL-8 from epithelial cells.

Minimum requirements for a rapid and reliable routine identification and antibiogram of Fusobacterium necrophorum.

Three hundred fifty-seven isolates of Fusobacterium necrophorum from human infections in Denmark were consecutively collected over a 3 year period for the purpose of establishing the minimum requirements for rapid and reliable routine identification of Fusobacterium necrophorum using phenotypic characters. The first 40 isolates were fully characterized by the most common phenotypic tests mentioned in the literature, while the last 317 where identified solely by the established minimum requirements for rapid and reliable routine identification of Fusobacterium necrophorum. All but one isolate were identical in all phenotypic tests. The outlying strain differed in morphology and the ability to agglutinate erythrocytes. On the basis of our findings it should be possible within 3-4 days to identify and differentiate F. necrophorum from other species including other Fusobacterium spp. by the unique but subspecies specific colony morphology, susceptibility to kanamycin and metronidazole, the smell of butyric acid, chartreuse colour fluorescence, and beta-haemolysis on horse blood agar. Three-hundred fifty-six isolates were identified as F. necrophorum subsp. funduliforme while one strain was F. necrophorum subsp. necrophorum. The species and subspecies level was confirmed for the first 40 isolates by real-time PCR. MIC in mg/l was determined for the 40 isolates. MIC(90) was 0.047 for penicillin, 0.047 for clindamycin, 0.25 for metronidazole, 0.38 for cefuroxime, >32 for imipenem, 0.012 for meropenem, and 2 for erythromycin. All 357 isolates were susceptible to penicillin and metronidazole indicating that these antibiotics are still the drugs of choice in antibiotic therapy of F. necrophorum infections, but therapy with clindamycin may be an alternative. Erythromycin should be avoided.