GI infections Flashcards
Clostridium botulinum
Canned/vacuum food (honey for kids, beans for students).
Ingest preformed toxin. Inactivated by cooking.
Blocks ACh release, so paralysis, descending (cf GBS).
Tx: antitoxin.
Clostridium perfringens
Reheated meats, superAg enterotoxin.
8-16 hours incubation.
Acts on small bowel. Watery diarrhoea, cramps, 24 hours.
Clostridium difficile
Caused by Abx (cephalosporins/fluoroquinalones (-floxacin)).
Exotoxins A and B. Pseudomembranous colitis.
Metronidazole, or vancomycin if bad.
Bacillius cereus
Reheated rice (spores). SuperAg, ^cAMP. 4 hours incubation. Sudden vomiting. Watery diarrhoea. Self-limiting.
Staph. aureus
G+. Catalase +, coagulase +. Tetrads. Beta-haemolytic.
Protein A stops IgG. Enterotoxin (superAg, IL1 IL2):
Prominent vomiting, water diarrhoea.
Self-limiting.
E coli
From human faeces.
G- enterobacter.
Facultative anaerobes, ferment lactose, oxidase -.
Self-limiting, but can give ciprofloxacin if dire.
ETEC
Toxigenic / Traveller’s E coli.
Heat labile toxin LT stimulates adenyl cyclase ^cAMP;
ST stimulates guanylate cylase ^cGMP. (stable Ground)
Jejunum and ileum.
EIEC
Invasive dysentery E coli.
EHEC
Haemorrhagic E coli, so bloody diarrhoea. Verotoxin.
EPEC
Paediatric E coli: infantile diarrhoea.
HUS
Anaemia, thrombocytopaenia, renal failure,
due to E coli 0157:H7 toxin.
Salmonellae
?
Salmonella typhi
Typhoid fever. Only transmitted by humans. Multiplies in Peyer's patches. Slow onset fever, *constipation*, spleen, rose spots, anaemia, leukopaenia. Ceftriaxone or ciprofloxacin.
Salmonella enteridis
Poultry, eggs, meat.
Invades small and large bowel; rarely bacteraemia.
Diarrhoea.
Self-limiting.
Shigella (dysenteriae)
Shiga enterotoxin,
Bloody diarrhoea
due to musocal inflam in distal ileum and colon.
Self-limiting.
Yersinia enterocolitis
Domestic animal poo.
Enterocolitis, mesenteric adenitis, necrotising granulomata, reactive arthritis, erythema nodosum.
4oC “cold enrichment”.
Vibrio cholerae
Human faeces, ? in shellfish.
cAMP opens Cl channel, lose Cl and water: massive diarrhoea without inflam.
Supportive Tx.
Vibrio parahaemolyticus
Raw seafood (Japan).
3 days diarrhoea.
Self-limiting, or Doxycycline.
Vibrio vulnificus
Shellfish - cellulitis in handlers.
In HIV: fatal septicaemia with D+V.
Doxycycline.
Campylobacter jejuni
Unpasteurised milk, poultry.
Curved, motile, oxidase +.
Prodrome: headache and fever.
Bloody foul smelling diarrhoea, abdo cramps.
Assoc: Guillain-Barré, reactive arthritis (Reiter’s).
Erythromycin (or cipro if early). (Sensitive to nalidixic acid, first quinolone).
Listeria monocytogenes
Refrigerated unpasteurised food.
L-shaped, beta-haemolytic, aesculin +, tumbling.
Sepsis / meningitis / diarrhoea, cramps, headache, fever.
Perinatal infection, immunocompromised.
Outbreaks of febrile gastroenteritis.
Ampicillin, ceftriaxone, cotrimoxazole.
Entamoeba histiolytica
Ingestion of cysts (MSM).
Motile trophozoite (or in non-diarrhoeal, non-motile cyst). nuclei.
Flask-shaped ulcers. Colonise colon.
Dysentery (blood, tenesmus), weight loss, RUQ pain (liver abscess).
Metronidazole + paramomycin.
Giardia lamblia
Ingest cysts from water. Travellers/MSM/mentals.
Pear-shaped trophozoites.
Malabsorption of protein and fat, so foul smelling diarrhoea.
Dx: ELISA string test.
Metronidazole.
Cryptosporidium parvum
Severe diarrhoea from infected jejunum in immunocompromised.
Oocysts in stool - modified Kinyoun acid fast stain.
Paramomycin.
