GI Diarrheal Micro Chart

Bug Lab SourceFood or

waterEmesis? Cramps? Fever? Onset Toxin Other Sx Dx Tx Other Path Morphology

Campylobacter

Jejuni

Gram negative curved rods

(seagull wings)

Microaerophilic;

growth at 42°C

undercooked poultry,

unpasteurized milk,

pets, large animal

reservoir

Food X X 1-7 d

MC bacterial cause of

gastroenteritis in US; flu like

sx, > 10 BM/day

blood + PMNs in

stool, cultureerythromycin DOC

GBS

reactive arthritis

(O:19)

cryptitis, crpyt

abscesses, presevered

crypt architecture

EHEC

0157: H7

gram negative rod, lactose

postive on MCA, indole positive;

colorless on SMAC (sorbitol

MacConkey agar) unable to

ferment sorbitol

Hamburger,

unpasteurized milk,

juices, petting zoos,

spinach, green onions;

P2P, F/O

Food X (50%) X 3-4 d

shiga like toxin

inhibits protein

synthesis

not invasive! Blood is 2* to

toxin; (invade/destroy colonic

epi); resolution in 4-10 d

screen on SMAC,

biochemical tests,

MCA,

immunoassay for

toxin

HUS (esp kids):

anemia, ↓ plts, renal

failure

TTP

EIEC



pink on SMAC (sorbitol

MacConkey agar)

X X shiga like invasive symptoms

blood + PMNs in

stool, culture; pink

on SMAC vs EHEC

rare in US

Shigella

P2P, low infective dose, acid

resistant, peds, daycare; taken

up my M cells → excapes from

vacuole → lyses M cell/infects

epi cell → replicates in cytosol

→ polymerizes F acAn →

propels to new cell;

blood + PMNs in

stool, culture;

MCCA, H2S neg,

ELISA, PCR

self limiting

abx tx to prevent

spread

Ampicillin DOC

TMP-SMX alt

HUS

mild: sonnei (MC in

US)

more severe: flexneri

(MC 3rd world) &

boydii

worst: dysentariae

L colon, hemorragic,

ulcerate mucosa, ?

Pseudomembrane,

apthous ulcers,

possible distorted

crypt architecure

Shigella

dysentariae

shiga toxin inhibits

protein synthesis

bacillary dysentery → PMNs,

RBCs, mucus in stool

supportive;

abx might ↑ toxinHUS

Non-typhoidal

Salmonella

poultry, eggs, dairy,

reptiles (turtles,

snakes, lizards),

tomatoes, jalapeno

peppers, peanut

butter

Food X X X 6-48 h

host response to ↑ cAMP not

a toxin!

Lasts 2-7 d, self limiting

supprotive

no abx unless patient

has septicemia

P2P

enteritidis MC

causes osteomyelitis

in sickle cell

Typhoidal

SalmonellaP2P X X X 10-14 d

taken up by M or epi cell →

destroys cell → replicates in

phagocytic cells; low infectious

dose; GB reservior for carriers;

HA, myalgia, anorexia, rose

spots

Fluoroquinolones

(DOC)

ceftriaxone in

preg/kids

tx carriers for 1-3 m

P2P only; fecal oral,

kids, not common in

US (must have travel

hx)

term ileum peyers

patch enlarged, oval

ulcers along axis

spleen: prominent

phagocyte hyperplasia

liver: scattered

necrossi →

macrophage

aggregates

Gram negative, lactose

negative, H2S positive, motile

(Salmon swim upstream)

Black pigment on

Hektoen enteric

agar

H2S positive

Bloody Diarrhea (ALL watery → bloody)

Blood + PMNs = inflammatory invasive diarrhea; large intestine

GI EXAM II Micro

Gram-negative rods, facultative

anaerobes, oxidase-, lactose-,

and H2S-negative

kids, P2P

MSM (asx colon

carriers)

fecal oral (not found in

environment)

X X 1-3 dP2P,

food


waterEmesis? Cramps? Fever? Onset Toxin Other Sx Dx Tx Other Path

Virbio cholerae Water ~ X 2-3 d

A/B toxin: B binds

to ganglioside

receptor, A1 ADP-

ribosylates

regulators of cAMP

→ ↑ cAMP → loss

of cell nutrients →

profuse diarrhea

rice water stool (no blood,

pus); rushes of peristalsis; 60%

death if untreated, < 1% c tx;

warmer months

fluid and electrolyte

replacement (glucose

c Na, Cl, K, HCO3)

Tetracycline shortens

course

TMP-SMX in kids

water borne

not P2P

S. America, India, SE

Asia

2 vaccines available

but not highly

effective

minimal

Virbrio

parahaemolyticusFood X X

X (low

grade)5-72 h

thermostable direct

hemolysin; ↑

intracellular Ca →

↑ Cl secreAon)

MC vibrio spp in US,

yearround; explosive D, HA,

abx

fluid and lyteswater borne

ETEC




MacConkey agar)

water borne

human fecal

contaimination

Food X X 1-2 d

1) heat labile (LT):

similar to cholera

(↑ cAMP)

2) heat stable (ST):

↑ guanylate

cyclase → ↑ cGMP

→ fluid secreAon

Traveler's diarrhea,

kids in dev countries;

nausea

Gram-negative,

ferments lactose,

indole positive

Ferments sorbitol

(SMAC agar - pink)

water borne

kids

EPEC




MacConkey agar)

X

babies and young kids

pathophys: disruption of

microvillus

bundle forming pili,

intimin (adhesion)

Clostridium difficile

Slender Gram-positive

sporulating anaerobe

Found in small numbers in GI

tract

X X 4-8 d

toxin A

(enterotoxin):

chemotactic for

PMNs → cytokine

release →

cytopathic → ↑

permeability of GI

wall → watery

diarrhea; toxin B

cytotxin

abx (clindamycin, lincomycin)

associated GI disease; SX:

profuse, watery, mucoid

green, foul smelling, diarrhea;

pseudomembranous colitis

Immunoassays for

toxin in stool

Isolation of

organism in stool

does not = disease

C. difficile is

normal flora

1) Stop broad-

spectrum antibiotic

treatment

2) PO vancomycin or

metronidazole

water borne

spores resistant to

disinfectants,

nosocomially spread

mucopurulent

exudate from cyrpts

like volcano

Yersinia

enterocolitica

Gram negative rod

Can grow at 4°C in culture

contaminated meat

(many types of

animals), milk, water

Food X X 1-10 d

mesenteric adentitis (enlarged

mesenteric lymph nodes);

children

cold enrichmentself limited;

Tetracylcine DOCrare in US

ileum, appendix, R

colon, lymph node

and peyers patch

hyperplasia, apthous

ulcers

Salmonella Chicken

Gram negative, curved rods

(comma shaped)

Oxidase positive, ferment

sucrose

Serotype O1:

1) classical

2) El Tor (mild D, carriers >

cases, survives longer)

Non O1: O139 in south inida

(new O antigen)

shellfish

halophilic marine

organism (found freely

living in environment)

reservoir is asx human

carriers

Small, rarely seen

on stool Gram

stain;

Darkfield

microscopy; TCBS

green → orange

Watery Diarrhea

toxin or virus; small intestine

Infections



S. AuresGram positive cocci, catalase

positive

Processed meats,

salted pork, custard

filled pastries, potato

salad, ice cream

XX 1-6 h

C. Perfringens

Commonreheated meat X 8-20 h

C. Perfringens

Rare

inadequately cooked

meat, esp porkX

C. BotilinumGram positive rods

Anaerobic, spore former

adult: canned food

infants: honeyX 12-36 h

Heat-labile

neurotoxin

Inhibits release of

acetylcholine

A, B, E, and F toxins

flaccid paralysis, initial

weakness and dizziness,

blurred vision, constipation,

dry mouth, dilated pupils

clinical

fecal sample

(infants) and food

source

infants: abx and

antitoxin

contraindicated

adults: antitoxin,

support, lavage

adults eat toxin

infants colonized by

bacteria

floppy baby

syndrome

Emetic

Bacillus cereus

reheated food, rice,

pulses

XX

rapid

onset

X < 6 hheat stable toxin

MOA ?

duration: < 24 h

intoxication

Diarrheal Bacillus

cereus

contaminated meat,

vegetables, saucesX 18 h

heat labile toxin: ↑

cAMP

duration: > 24 h;

not intoxication!

Bacteria multiply in GI tract,

release toxin



Rotavirus

cubic symmetry and outer

capsid coat arranged like spokes

of wheel; dsDNA

X

infants; destroys epi cells →

villous atrophy → osmoAc D,

projectile vomiting; cough,

coryza

↑ virus in stool< 2 years old

colder months

small intestine, villus

surface replaced by

immature secretory

cells

Norovirus

(Calcivirus)

ssRNA

virus binds to ABH histo-blood

group antigens

Food X X Xcruise ship, older pts; HA,

myalgia, fever, NVD

highly infections,

rapid spread; colder

months

small intestine, mild

villous shortening, epi

vaculoization, loss of

microvillus brush

border, crypt

hypertophy

Tropheryma

whippeliiGram-positive rod X X

Whipple disease: wasting

illness characterized by

arthralgias, arthritis, fever, and

diarrhea, steatorrhea, weight

loss, GI bleed

PCR

PAS positive

prolonged > 1 yr TMP-

SMX, pcn,

streptomycin

Very rare disease

foamy macrophages,

PAS positive, villous

expansion

Listeria

monocytogenes

gram + coccobacillus

food borne (unpast. Milk)Affects on fetus:

Heat labile enterotoxin, serotype A; enzymatic lysis; α toxin

(phosplopase C) hydrolyses cell phosphorylchorine in cell membrane →

cell death

heat stable, resistant to enzymes; A MC, B

psuedomembranous, C/D: dairy; Severe

vomiting and watery diarrhea

superantigen; α toxin causes pore formation → loss of nutrients →

cell death

NO DIARRHEA

Reheating food degrades toxin

self limited, lasts 24-48 h

β-toxin producing serotype C; pts have ↓ protein diet → ↓ intesAnal

trypsin → bacterial able to make trypsin sensiAve toxin

acute necrotizing disease "Pig-bel:" Bloody

diarrhea, abd pain, 50% mortality 2* abd

perforation

Gram-positive rods, aerobic

spore former

Culture and Gram

stain of

suspected food

Isolation from

fecal sample not

usually performed

due to

contamination

supportive;

Vancomycin DOC

alts: clindamycin,

cipro, or gentamicin

fetal death or malformations; premature delivery, neonatal septicemia, pna c abscesses or granuloms

Other

Intoxications aka true food poisoning

Watery Diarrhea

toxin or virus; small intestine

Gram positive rods

Anaerobic, spore formers

β-hemolytic

GI Diarrheal Micro Chart

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