ENTEROBACTERIACEAE, VIBRIO, CAMPYLOBACTER AND HELICOBACTER Faculty: Dr. Alvin Fox

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Key Words Opportunistic diseases Shigella Diarrhea Bacillary dysentery Diarrhea Shiga toxin Salmonella enteritidis Urinary tract infections Lactose positive/negative Salmonellosis Salmonella cholerae-suis Enteropathogenic E. coli Enterotoxigenic E. coli Salmonella typhi Heat stable toxin Typhoid Heat labile toxin Vi Yersinia entercolitica Enteroinvasive E. coli Enterohemorrhagic E. coli Vibrio cholerae Vero toxin (Shiga-like) Choleragen (cholera toxin) Campylobacter jejuni Hemolysin pili Helicobacter pylori ٢

Opportunistic diseases -Enterobacteriaceae – – – –

septicemia, pneumonia, meningitis urinary tract infections Citrobacter Enterobacter Escherichia Hafnia Morganella Providencia Serratia

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Enterobacteriaceae • gastrointestinal diseases – Escherichia coli – Salmonella – Shigella – Yersinia entercolitica

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Reiter's syndrome • Histocompatibility antigen (HLA) B27 – Enterobacteriaceae *Salmonella *Shigella *Yersinia – Not Enterobacteriaceae *Campylobacter *Chlamydia ٥

Enterobacteriaceae • community acquired • otherwise healthy people – Klebsiella pneumoniae * respiratory diseases * prominent capsule –urinary tract infection –fecal contamination *E. coli *Proteus – urease (degrades urea) – alkaline urine

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Enterobacteriaceae • gram negative facultative anaerobic rods – oxidase negative (no cytochrome oxidase)

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Feces • E. coli – lactose positive – not usually identified – lactose positive sp. common, healthy intestine • Shigella, Salmonella,Yersinia – lactose negative – identified ٨

Enterobacteriaceae • other sites – identified biochemically

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Serotypes • reference laboratory – antigens • O (lipopolysaccharide) • H (flagellar) • K (capsular)

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Diarrhea and Dysentery

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Escherichia coli

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Escherichia coli • E. coli and Shigella – genetically very similar – many similarities in diseases

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Enteropathogenic E. coli destruction of surface microvilli • fever • diarrhea • vomiting • nausea • non-bloody stools

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Enterotoxigenic E. coli • diarrhea like cholera • milder • travellers diarrhea

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Enterotoxigenic E. coli • Heat labile toxin – like choleragen – Adenyl cyclase activated – cyclic AMP – secretion water/ions • Heat stable toxin – Guanylate cyclase activated – cyclic GMP – uptake water/ions

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Enteroinvasive E. coli (EIEC ) • Dysentery - resembles shigellosis

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Enterohemorrhagic E. coli • Usually O157:H7 Flagella

Transmission electron micrograph

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Meat • Hemorrhagic – bloody, copious diarrhea – few leukocytes – afebrile • hemolytic-uremic syndrome – hemolytic anemia – thrombocytopenia (low platelets) – kidney failure ١٩

Enterohemorrhagic E. coli • Vero toxin – “shiga-like” • Hemolysins

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Treatment -gastrointestinal disease • fluid replacement • antibiotics – not used usually unless systemic – e.g. hemolytic-uremia syndrome

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E. coli fimbriae Type 1 mannose

P

galactose – glycolipids – glycoproteins ٢٢

Shigella • S. flexneri, S. boydii, S. sonnei, S. dysenteriae – bacillary dysentery – shigellosis • bloody feces • intestinal pain • pus

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Shigellosis • within 2-3 days – epithelial cell damage

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Shigella sonnei

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Shiga toxin • enterotoxic • cytotoxic • inhibits protein synthesis – lysing 28S rRNA

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Shigellosis • man only "reservoir" • mostly young children – fecal to oral contact – children to adults • transmitted by adult food handlers – unwashed hands ٢٧

Treating shigellosis • manage dehydration • patients respond to antibiotics – disease duration diminished

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Salmonella Flagella

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Salmonella • 2000 antigenic "types” • genetically single species – S. enterica

• disease category – S. enteritidis – many serotypes

– S. cholerae-suis – S. typhi

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Salmonellosis • S. enteritidis – the common salmonella infection – poultry, eggs – no human reservoir – Gastroenteritis • • • •

nausea vomiting non-bloody stool self-limiting (2 - 5 days) ٣١

Salmonellosis

uncomplicated cases (the vast majority) antibiotic therapy not useful

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S. cholerae-suis • much less common • septicemia • antibiotic therapy essential

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Typhoid • • • • •

enteric fever severest salmonella disease Salmonella typhi rare in US epidemics – third world – Europe * historical ٣٤

Salmonella typhi • human reservoir – carrier state common

• contaminated food • water supply • poor sanitary conditions ٣٥

Typhoid

septicemia - occurs 10-14 days – lasts 7 days

gall bladder –shedding, weeks acute phase, gastroenteritis

gastrointenteritis

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S. typhi • Vi (capsular) antigen – protective

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Typhoid -Therapy • Antibiotics – essential • Vaccines – ineffective

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Yersiniosis • Yersinia entercolitica – gastroenteritis – Scandinavia common – US *colder regions

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Yersiniosis • transmission – fecal contamination, domestic animals • water • milk

– meat

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Yersinia

Diarrhea fever abdominal pain antibiotic therapy recommended occassional bacteremia ٤١

Yersinia -isolation cold enrichment

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Y. pseudotuberculosis • similar • less severe disease

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Vibrio cholerae

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Vibrios • Gram negative rods • comma shaped • facultative anaerobes • oxidase positive • simple nutritional requirements • readily cultivated

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Occurrence -cholera • third world • US – uncommon *traveler *ingestion of sea-food

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Transmission - V. cholerae feces

water – fresh – salt

food

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Cholera - attachment

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Cholera toxin- Choleragen • B binds to gangliosides • provides channel for A • A catalyses ADP-ribosylation – regulator complex – activates adenylate cyclase ٤٩

Cholera -therapy • massive secretion of ions/water into gut lumen • dehydration and death • therapy – fluid replacement – antibiotic therapy • vaccination – partially effective – not generally used – international travelers ٥٠

Vibrio parahemolyticus • raw sea-food • grows best in high salt • not common in US • diarrhea

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CAMPYLOBACTER & HELICOBACTER • Gram negative rods • curved or spiral • genetically related

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Campylobacter

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C. jejuni • infects the intestinal tract of animals – cattle and sheep – major cause of abortions

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Transmission • milk • meat products

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Campylobacter

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Isolation - Campylobacter • microaerophilic • grows best 42oC

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Campylobacter - symptoms • diarrhea • malaise • fever • abdominal pain • usually self-limiting • antibiotics occassionally • bacteremia –small minority ٥٨

Helicobacter pylori • stomach mucosa • ulcers

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Urease • Important in neutralizing stomach acid

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Diagnosis -Helicobacter • Culture - urease NH4+ CO2 • mucosal endoscopy NH4 • radioactive CO2 breath after feeding radioactive urea

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Therapy -Helicobacter • Antibiotics – cures ulcers

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Summary statement • sanitary measures – protect the water supply • food/water borne epidemics – rare US – common third world • zoonotic infections – contaminated animal products – less well controlled – common US and elsewhere

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Therapy • severe diarrhea – fluid replacement essential • antibiotic therapy sometimes used in local infection but always in systemic disease

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