GI Infections Flashcards
Staph aureus infection
- Spreads from hands of poultry workers
ONSET WITHIN 6H
- Presents with watery, non-bloody vomiting and diarrhoea lasting 24h
5 C’s of S. aureus:
- Cocci
- Clusters
- Catalase +ve
- Coagulase +ve
- Clusters (yellow clusters form on blood agar)
Bacillus cereus infection
- Associated with reheating fried rice
- ONLY 4 HOURS INCUBATION !
- Spore-producing bacteria
- Produces 2 toxins:
Heat-stable emetic toxin
- Causes symptoms (vomiting) when food is not reheated properly
Heat-labile diarrhoea toxin
- Causes symptoms when food is not cooked to a high enough temperature
Symptoms resolve in 24h but B. cereus can sometimes cause cerebral abscesses
Clostridium botulinum
- Associated with tinned food and vacuum-packed food
- Honey should not be given to infants <1y due to risk of infection
- Inactivated by cooking
- Causes paralysis
- Manage with antidote
Clostridium difficile
- Associated with antibiotic use, thought to be HAI
- Causes pseudomembranous colitis
- Tx with mentronidazole ± vancomycin and stop other Abx where possible.
4 C’s - Culprits of C. diff
- Cephalosporins
- Co-amoxiclav
- Clindamycin
- Ciprofloxacin
Clostridium perfringens
- Associated with not cooking food properly
- <24h incubation
- Watery diarrhoea and cramps lasting 24h
- Superantigen acts on the collon but not in small bowel
Listeria monocytogenes
- Associated with refrigerated food especially non-pasteurised milk
- Febrile gastroenteritis with watery diarrhoea
- Babies are susceptible
- Tx with ampicillin
Listeria monocytogenes is:
- beta-haemolytic
- Aesculin +ve
- Tumbling mobility
E. coli
2 Enterotoxins:
- Heat labile toxin - acts on adenylyl cyclase and CAMP
- Heat stable toxin - acts on guanylate cyclase
Different subtypes:
- EPEC - Pathogenic, infantile diarrhoea
- EIEC - Invasive, dysentery
- ETEC - Toxinogenic, travellers
- EHEC - haemorrhagic - o157 is the shiga-like verotoxin that causes HUS
12-48 INCUBATION
Mx - supportive care and avoid Abx
Salmonella - overview
- Gram negative
- Non-lactose fermenters
12-48H INCUBATION
- Recurrent Salmonella infections can occur in association with reptiles as pets
Salmonella enteritidis
- From poultry, eggs and meat
- Binds to epithelium and subepithelium in the jejunum and ileum but not in the large bowel
- Causes watery, non-bloody diarrhoea
- Blood culture -ve but stool sample +ve
- Mx - none needed
Salmonella typhoides (Typhoid enteric fever)
- Multiplies in Peyer’s patches and spreads through reticuloendothelial system
- Slow onset fever and CONSTIPATON
- Blood culture +ve
- Causes splenomegaly, rose spots, bradycardia, leukopenia, haemorrhage, shock
- mx with ceftriaxone
Salmonella antigens
- Cell wall O
- Flagellar H
- Capsular IV
Shigella
- Non-lactose fermenter and non-hydrogen sulphide producer
- Produces Shiga toxin which invades the mucosa of distal ileum and colon
48 - 72H INCUBATION
- Causes DYSENTERY
- Usually self-limiting, supportive tx only
- CIprofloxacin can be used if needed
Vibrio cholerae
- Comma shaped
- Found in water contaminated with human faeces e.g. shellfish
- There is colonisation of the small bowel and RICE WATER STOOL
- Supportive tx
Vibrios haemolyticus
- Raw seafood/sushi
- Self-limiting, lasts 3 days
- Only grows on salty agar - (seawater is salty)
- Supportive care
Vibrio vulnificus
- Causes cellulitis in shellfish handlers
- In HIV patients, can cause severe sepsis and D&V
- Tx with doxycycline
