Microbiology of Diarrhea Flashcards Preview

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Flashcards in Microbiology of Diarrhea Deck (23):
1

Rotavirus (reoviridae)

Genetic material, # of capsids, envelope?

Pop

CM

Transmission

Pathophys

dsRNA, 2, naked

Day care

Fever, NV, watery diarrhea (4-8days)

F/O- low infectious dose

Infect enterocytes in middle/upper villi- destroy epithelial cells- dec absorptive surface in SI, dec transfer of fat/carb

2

Noravirus (calciviridae)

Genetic material, envelope?

Typical areas

Incubation sx

CM

Transmission

ssRNA, naked, heat resistant capsid

cruise ship/plane/nursing

V/D

watery diarrhea for 2-3 days

F/O via food/water or surfaces/fomites

3

Shigella
Salmonella

E coli

Gram - rods

Camp

oxidase -, Lactose nonfermenter
oxidase -, lactose nonfermenter

lactose fermenter



4

Vibrio cholerae

Shape

Phage encodes

Transmission

CM

Gram -, vibrio

cholera toxin

food/water w feces

watery diarrhea (rice water), voluminous, vomiting/fever

5

Vibrio parahaemolyticus

Commonly transmitted via

CM

Lasts

shellfish

watery diarrhea, NV

10 days

6

Cholera disease pathway

A1 catalyzes

leads to

Ingested- release endotoxisns- binds to GM1 ganglioside

Gs w loss of GTPase activity

AC activation, inc cAMP/kinases- diarrhea, loss of electrolytes

7

C diff

Pathophys

A and b toxins cause

Detect toxins becasue

spores introduced, germinate, inc undigested carbs- watery diarrhea

epithelial cells to detach, ulcers to form, psuedomemebrane

Toxin mediated dz

8

Giardia lamblia

Type

Exposure areas

Cyst stage

trophozoite

Pathophys

Dx

anaerobic, flagellated protozoa

water/day care/pets

infectious (4 nuclei)

reproductive/pathogenic

troph to BB, attaches disk, blunts MV, fat malabsorption= steatorrhea

Stool antigen test/trophozoites (stingray w 2 nuclei

9

Crypto

CM competent

IC

Pathophys

Dx

ab pain, nausea, wl

chronic, watery diarrhea

oocysts in SI- sporozoites attach to epithelial cells-replicate in IC vacuole

acid fast oocysts in stool

10

ETEC patho

leads to

stimulates (LT)
ST

Dx

labile heat toxin binds GM1

travelers/watery diarrhea

AC-cAMP-secretion
GC

serology for toxin

11

EHEC patho

transmission

CM

Dx

bactera attaches, MV damaged, delivers toxin to EC fluid

undercooked meat

bloody diarrhea, no fever

0157H7 in stool

12

Campylobacter

Type

CM

Pathophys

gram - curved rod, microaerophilic

fever, malaise, watery diarrhea- blood, tenesmus, leukocytes (if bloody)

invades epithelium-inflamm- RBC/WBC in stool

13

Salmonella

Type

Infectious dose

Incubation time

Pathophys

diarrhea resolves in, fever in

Gram neg rod

high

24-72 hrs

bacteria invade enterocytes in SI/colon- migrate to LP of iliocecal region- cytokines cause cap dilation/PMN relase- water leaks into lumen

3-7 days
7 days

14

Shigella

Type

Infectious dose

CM

Due to shiga toxin, stools area*****

Shiga toxin targets

Complications

gram neg rod

low

high fever, ab pain, bloody diarrhea

frequent

60s ribosome- stops protein synthesis

TM and HUS

15

Shigella Pathophys

invades epithelial cell

uses actin tails to invade

uptake by M cells- macros- apoptosis and inflamm

release PMN- use T3SS to release toxin/rearrange cytoplasm- cells die (bloody/mucus)

neighboring epithelial cells

16

Yersinia

Type

Grows in

Incubation

CM

Avg length of time

Pathophys

Mimics

Encodes

Gram neg, urease pos rod

Cold temp

4-6 days

HA/anorexia/fever/bloody and mucus diarreha

2 wks

invades ileal epi- enters LP/PP- drains to LN- intestinal inflamm sheds PMNs/RBC in lumen

appendicitis

iron uptake system for virulence/dissemination

17

Entamoeba histolytic

Incubation time

Transmission

CM

Dx

Complication

2-6 wks

cysts from fecal/oral

lower ab pain, bloody mucoid stool, wl

amebic cysts (4 nuclei) or trophs (RBC)

infects liver, RUQ pain- abscess

18

Life cycle of entamoeba histolytic

ingested then

cysts released in

forms trophs- penetrates intestinal wall- multiplies- invasion



feces

19

Nematodes

body style

transmission

ingested

invasion of skin

round, unsegmented

eggs- enterobius/ascaris/trichuris

larval form- necator/stronglyoids

20

Ascaris

pathophys

complications

MC

dx

ingest egg- larvae to lungs- aspirate- enter SI

eosinophilia/IO/BDO

helminth

knobby eggs in stool

21

Enteriudes vermicularis incubation time

4-6 wks

22

Necator

Larvae penetrate

Strongyloides

Larvae penetrate

SX

intact skin of bare feet

intact skin, do not mature

Duodenitis/PNA/colits/malabsorption

23

Trichuris trichuria

transmission

pathophys

F/O or through soil

larva enter SI to cecum- release eggs in stool