GI Infections

Question 1

Clostridia Botulinum

Answer 1

Anaerobic

Canned/vacuumed packed foods

Botulin toxin –> Descending paralysis

Blocks Ach release

Give antitoxin

Question 2

Clostridia Perfringens

Answer 2

Anaerobic

Reheated meats

Superantigen enterotoxin

8-16 hrs incubation

Watery diarrhoea + cramps

Lasts 24 hours

Also causes gas gangrene

Question 3

Clostridia Difficile

Answer 3

Anaerobic

2 exotoxins A, B

Pseudomembranous colitis

Tx: Metronidazole (and then vancomycin)

Question 4

Bacillus cereus

Answer 4

Aerobic

Reheated rice

Superantigen

4 hrs incubation

Question 5

Staph Aureus

Answer 5

Aerobic

Catalse coagulase positive

Beta haemolytic on blood agar

Superantigen

Prominent vomiting and watery non-bloody diarrhoea

Self-limiting

Question 6

E. Coli

Answer 6

Gram negative enterobacteriaceae

Facultative anaerobes oxidase negative

Lactose fermenting

ETEC

EIEC

EHEC

HUS

EPEC

Question 7

ETEC

Answer 7

Enterotoxigenic Escherichia coli

Toxigenic

Traveler’s diarrhoea

Heat labile LT stimulates adenyl cyclase and cAMP
Heat stable stimulates guanylate cyclase

Question 8

EIEC

Answer 8

Enteroinvasive Escherichia coli

Invasive dysentery

Question 9

EHEC

Answer 9

Enterohemorrhagic Escherichia coli

Haemorrhagic

Verotoxin

Question 10

EPEC

Answer 10

Enteropathogenic E. coli

P = paediatric infection

infantile diarrhoea

Question 11

Salmonella Typhi

Answer 11

(and paratyphi)

Non-lactose fermentors

Enteric fever

Multiply in Peyers patches

Slow onset fever and CONSTIPATION

Relative bradycardia

Splenomegaly

Rose spots

Anemia

Leukopenia

Tx: Ceftriaxone or ciprofloxacin

Question 12

Salmonella enteritides

Answer 12

Non-lactose fermentor

Poultry, eggs and meat

Small and large bowel invasion

Non-bloody diarrhoea

Tx: ceftriaxone or ciprofloxacin if required

Question 13

Shigella

Answer 13

Non-lactose fermentor

Distal ileum + colon

Mucosal inflammation

Fever

Pain

Bloody diarrhoea

Shiga enterotoxin

Ciprofloxacin if required

Question 14

Yersina enterocolitis

Answer 14

Non-lactose fermentor

Enterocolitis

Mesenteric adenitis

Necrotising granuloma

Erythema nodosum

Cold enrichment 4’C

Question 15

Vibriosis Cholera

Answer 15

Comma shaped

Late lactose fermentors

Oxidase positive

Rice water stool

Increased cAMP –> open Cl- channel

Question 16

Vibriosis parahaemolyticus

Answer 16

Comma shaped

Late lactose fermentors

Oxidase positive

Ingestion of raw undercooked seafood (common in Japan)

3/7 diarrhoea

Self-limiting

Doxycycline

Question 17

Vibriosis Vulnificus

Answer 17

Comma shaped

Late lactose fermentors

Oxidase positive

Cellulitis in shell-fish handlers

fatal sepsis and D&V in HIV patients

Doxycycline

Question 18

Campylobacter Jejuni

Answer 18

Curved, comma, or S-shaped

Microaerophilic

Oxidase positive

Unpastuerised milk

Prodrome: headache, fever, abdo cramps

Bloody diarrhoea (foul smelling)

Assoc with Guillian-Barre, Reactive arthritis

Question 19

Listeria monocytogenes

Answer 19

Beta haemolytic

Tumbling motility

Aesculin positive

Watery diarrhoea

Cramps, headache, fever, some vomiting

Ampicillin, Ceftriaxone, Co-trimoxazole

Question 20

Entamoeba histolytica

Answer 20

Protozoa

MSM
Food, water and soil

Motile trophozoite in diarrhoea

Non-motile cyst in non-diarrhoeal illness

4 nuclei

Flask-shaped ulcer

Dysentery
Wind
Tenesmus

chronic weight loss and RUG pain due to liver abscess

Metronidazole + Paromomycin

Question 21

Giardia Lamblia

Answer 21

Protozoa

Travellers, Hikders, MSM, psych units

Pear shaped trophozoites / cysts found in stool

cysts in water

Malabsorption of fat and protein

Foul smelling bloody diarrhoea

ELISA string test

Tx: Metronidazole

Question 22

Cryptosporidium Parvum

Answer 22

Protozoa

Jejunum

Severe diarrhoea in immunocompromised

Modified Kinyoun acid fast stain —> see oocysts

Tx: Paromomycin

Question 23

Viral diarrhoea

Answer 23

Rotavirus

Adenovirus

Norovirus

Poliovirus

Enteroviruses (coxsackie, ECHO)