THE GENUS HELICOBACTER Gram –ve rod, curved microaerophilic oxidase + strong urease activity At least 22 species included in this genus Majority colonize mammalian stomach or intestine Human pathogens : H. pylori, H. cinaedi, H. fennelliae

H. pylori : * Mode of transmission is unclear oral-oral, fecal-oral houseflies, ingestion * Cultured from feces and dental plaque * 50% of adults older than age 60 are infected * Highest rates of initial infection occur by age 10 especially between ages 4-5 year

Pathogenesis & Pathogenicity  colonizes the mucous layer of the antrum and fundus of stomach  does not invade the epithelium  ability to colonize the gastric mucosa  genome is the most variable sequence, changing the expression of OMP  persist host immune defense  cause host tissue damage Gastritis, peptic ulcer, gastric cancer

Duodenal peptic ulcer

Virulence factor :  surface is covered with urease enzyme produce ammonia (base) from urea in the host, help to protect from acid  adhesins for colonization of mucosal surfaces  stimulate cell to initiate mediators of inflammation  cytotoxin causes damage to gastric epithelial cells

H. cinaedi and H. fennelliae * cause proctitis, enteritis, sepsis in homosexual men * septicemia, cellulitis and meningitis in immunocompromised patients

H. pylori in cats : * has been cultured from feces, salivary secretion, gastric fluid and dental plaque of naturally-infected cats * infected cats had moderate to severe lymphofollicular gastritis * clinical sign : vomiting, weight loss possibly diarrhea (subclinical sign) Feline isolates shown to be genetically similar to human isolate (99.7% identity in 16s rRNA)

Human to cats to human transmission of H. pylori as a reverse zoonosis? * Epidemiologic studies H. pylori infection and animal contact are conflicing * Overall rate of colonization of stray cats much lower than that of humans * Humans may the 1 ry reservoir of the organism humancat

Dogs and cats H. felis H. bizzozeronii H. salomonis (naturally infected dog)  asymptomatic, some show intermittent vomiting, weight loss and emaciation  possibility of zoonotic infection has been considered

H. heilmannii  associated highest infection rates in dogs and cats (group confinement)  % human gastric cases species resembling H. heilmannii isolated from cats and dogs

H. bizzozeronii * found in gastric mucosa * pig contact is an important risk for humans * infection of humans: milder from of chronic gastritis than H. pylori and may be self-limiting swine, dog, and cat, human)

Other Helicobacter : H. mustelae- hypergastrinemia in ferret H. acinomyx- gastritis in cheetah H. cinaedi- part of flora of hamster H. suis - swine, gastric ulcer

There has been no report pointing to a direct relationship of human infection by animal helicobacter spp. and gastric disorder in human caused by H. pylori

Direct Detection : * Warthin-Starry stain, silver stain, Giemsa biopsy specimens * placing crush tissue biopsy in urea broth * Urea breath test * H. pylori stool antigen tests

Isolation & Identification * Demonstration of histologic evidence of inflammatory changes accompanied by spiral organism in mucosa Biopsy speciman : Gastric mucosa e.g. chocolate agar, brucella agar + 5% sheep blood 4-7 days of incubation

Biochemical test typical cellular morphology Positive results for : Oxidase Catalase Rapid urease test etc. (from table)