fusobacterium fusobacterium fusobacterium is a genus of anaerobic, gram-negative, non-sporeforming bacteria belonging to gracilicutes. individual cells are slender, rod-shaped bacilli with pointed ends. fusobacterium fusobacterium novum in liquid culture scientific classification domain: bacteria phylum: fusobacteriota class: fusobacteriia order: fusobacteriales family: fusobacteriaceaestaley and whitman 2012 genus: fusobacteriumknorr 1922 type species fusobacterium nucleatumknorr 1922 species f. animalis f. canifelinum f. equinum f. gastrosuis f. gonidiaformans "f. hwasookii" "f. massiliense" f. mortiferum f. naviforme f. necrogenes f. necrophorum f. nucleatum f. perfoetens f. periodonticum f. polymorphum "f. pseudoperiodonticum" "ca. f. pullicola" f. russii f. simiae f. ulcerans f. varium f. vincentii f. watanabei strains of fusobacterium cause several human diseases and infections, including periodontal diseases, lemierre's syndrome, oral, head, and neck infections, as well as colorectal cancer and topical skin ulcers. it has also been tied to hiv infection and suboptimal immune recovery. detection of fusobacterium is typically through surgical retrieval of tissue as well as testing of fecal matter and blood given the patient is showing symptoms. early detection is preferred and best to avoid further development. although older sources state that fusobacterium is part of the normal flora of the human oropharynx, the current consensus is that fusobacterium should always be treated as a pathogen. fusobacterium currently has 13 strains; the main one affecting humans is f. nucleatum while f. necrophorum follows as well as affecting animals, mainly cattle. clinical relevance fusobacterium is often associated with ulcerative colitis. research of colon cancer has also shown an overrepresentation of fusobacterium, both in feces of patients and tumor issue itself. fusobacterium has also been seen increased in individuals infected with hiv as well as in individuals with suboptimal immune recovery as compared to patients who were not infected and had optimal responses. f. nucleatum is found in humans more so than any other species of fusobacterium. it is commonly found in the oral cavity as well as in the intestinal tract. some of it's pathogenic ties includes it's extraction from amnoitic fluid sourced from spontaneous premature labor without reason/a given source. a few additional sources of it's pathogenic nature inclue it's association with oral inflammation diseases, cancers such as pancreatic, oral, and colorectal, as well as infections of the head and neck. this association is due to the high increase in the prevalence of f. nucleatum in those infected areas. f. nucleatum can worsen or initiate colorectal cancer by stimulating other gram-negative bacteria such as streptococcus, campylobacter spp. and leptotrichia as well as cancerous gene expression from beta-catenin signaling. f. nucleatum can be detected in tissues, genomic dna, and feces using methods such as (fq, q, and dd) polymerase chain reaction and fluorescence in situ hybridization. however, these are limited because tissues can only be tested after surgery and fecal matter can return false positive results. f. necrophorum has been found as a common pathogen in the diagnostic of peritonsillar abscess and is more prevalent than other bacteria regarding this infection. it is also the most frequent leading cause associated with lemierre syndrome and is not proven to be a normal part of the human oral bacterium population. f. necrophorum commonly infects animals, causing liver abscesses and necrodic diseases, and can combine with other pathogenic bacteria to cause various infections such as foot rot and uterine infections. f. ulcerans is very similar to f. varium and is commonly extracted from tropical ulcers. f. necrogenes is also closely related to f. ulcerans and f. varium and has been found in chickens and ducks. however, it is not often extracted from any infections sourced from both humans and animals. this is the same case for f. perfoetans which is sourced from fecal matter. f. gonidiaformans is typically found in the intestines of humans and is not found orally like the other fusobacterium. f. russi is a common bacteria in canine and feline oral cavities and can lead to the infection of puncture wounds if transferred to humans from bites. another common oral bacteria is f. simae which can be sourced from monkeys. the bacterium is a big anchor for biofilms. it is usually susceptible to clindamycin, while approximately 20% of the clinical strains are resistant to penicillin. in contrast to bacteroides spp., fusobacterium has a potent lipopolysaccharide. fusobacterium infections often cause clinical symptoms such as a fever, inflammation, and a diseased appearance. further diagnosis can confirm suspicions of fusobacterium infection through blood testing or culturing the tissue. upon diagnosing the infection, action to treat it involves the application of antibiotics over a 2 week period which could be in the form of penicillin or other variants as well as using anaerobic antibiotics like clindamycin and metronidazole which work when the fusobacterium can break down the beta-lactams. leaving fusobacterium untreated could lead to more severe developments of the infection and early testing is recommended.by testing early, fatal diseases such as lemierre syndrome can be avoided. however, this requires the family physician to be conscious of the danger as infections such as lemierre syndrome affects younger populations and especially those of male gender. phylogeny