Gram negative Enteric bacteria

Microbiology 1 with Swierkosz at Saint Louis University

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By: Brian Nguyen
Created: 2011-02-04
Size: 28 flashcards
Views: 5

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Enterotoxigenic E. coli (affected site, diarrhea, fever, pathogenic mechanism)

Small intestine (actin polymerization leads to loss of microvilli), non bloody copious diarrhea, no fever.

LT binds, activated adenylate cyclase, produces cAMP, pumps out ions and water

ST elevates cGMP

Enteropathogenic E. coli (affected site, diarrhea, fever, pathogenic mechanism)

Small intestine, copious non-bloody, fever.

Organism binds to epithelial cell, rearranges cytoskeleton (effective loss of microvilli)

Enterohemorrhagic E. coli (affected site, diarrhea, fever, pathogenic mechanism)

Binds to large intestine, copious bloody diarrhea, no fever

Binds to brush border, makes toxin (verotoxin) that destroys microvilli, toxin enter blood causing damage and platelet aggregation. Thrombi cause ischemic damage to colon and kidneys

Enteroinvasive E. coli (affected site, diarrhea, fever)

"Invades" large intestine, bloody purulent diarrhea, fever

Extraintestinal diseases E. coli

UTIs

From bladder infxn (cystitis) to kidney infection (pyelonephritis)

Symptoms just dysuria to obstructed urinary flow, fever, chills, etc

Neonatal meningitis, nosocomial infections (in compromised pts)

Salmonella

Both intra and extraintestinal infections

Gram neg, motile, H2S pos, rods, facultative, oxidase neg, lactose neg

S. typhi - encapsulated, exclusively human pathogen

High infectious dose (>10^5 orgs)

Salmonellosis (gastroenteritis)

Nausea, vomiting, diarrhea (non-bloody, maybe bloody)

Mostly self-limited, localized

May move to osteomyelitis in the compromised, possible disseminated infection (bacteremia, pneumonia, meningitis)

Enteric (typhoid) fever

Caused by S. typhi

Sever, life-threatening systematic disease with high fever/chills, abd symptoms

Infection disseminates into blood

ATM transmission, human-to-human

Can hide in biliary tract

Shigella (properties)

Gram neg, facultative, oxidase neg, lactose neg, h2s neg, non-motile, non encapsulated

Mostly enteric infection - bloody, mucus diarrhea, painful abdominal cramping

Humans only reservoir, low infectious dose (<200orgs)

Shigella (pathogenesis)

Invasion of M cells in large intestine, rarely penetrates deeper

Invades neighboring cells, mucosal abscess when infected cell dies

Shiga toxin with enterotoxic and cytotoxic properties, inflammation

Campylobacter (properties)

Gram neg, curvy S-shaped

Darting motility

Oxidase pos, urease neg

Microaerophilic, thermophilic

Mostly in GI, but can get out

C. jejuni (diarrhea), C fetus (systematic)

Campylobacter (epidemiology)

Many zoonotic reservoirs - cattle, poultry, dogs, etc

Fecal-to-oral transmission

Most common cause of bacterial diarrhea

C. jejuni (pathogenesis)

Low infectious dose

Colonizes mucosa, invades underlying tissue

Acute enteritis, self-limiting

C. jejuni associated Guillain-Barre syndrome

Demyelinating neuropathy

Autoimmune cross reaction between neuron gangliosides and LPS on the microbe

Vibrionaceae (properties)

Gram neg, curved comma shaped

Highly motile

Facultative, oxidase pos,

Inside GI tract

Vibrionaceae (epidemiology)

No animal reservoir

Human to human, contaminated water --> seafood, undercooked shellfish

V. cholerae (O:1) - epidemic cholera

Vibrionaceae cholerae (pathogenesis)

Large infectious dose, organisms lack acid resistance

Adhere to brush border in small intestine

Non invasive

Choleragen toxin (CTX) - A-B toxin (same mechanism of ETEC)

ADP ribosylation raises cAMP levels, excretion of ions and water

Non-cholera vibrios

From brackish, salt water

V. parahaemolyticus - diarrhea, to dysenteric

V. vulnificus - soft tissue infections, systematic disease in compromised patients

Yersinia (properties)

Gram neg, lac neg

Grows well at low temps

Yersinia (epidemiology)

Transmitted from food/water contaminated with animal feces (dogs, cattle, cats)

Yersinia (pathogenesis)

Enterocolitis similar to shigella/salmonella

Rarely systematic, except in compromised pts

Ulcerative lesions in ileum, fever, pain, bloody diarrhea

Yersinia (identification)

Isolated on selective media

Needs to be serotyped because it looks like salmonella

Heliobacter (properties)

gram neg, curved S-shaped rods, oxidase pos, urease pos

Microaerophilic, campy-like

Heliobacter (epidemiology)

Colonizes stomach

Causes gastritis, peptic ulcers

Heliobacter (pathogenesis)

Penetrates mucosal layer, urease produces ammonia

Ammonia damages mucus cells, neutralizes pH and protects organisms

Damage to mucus cells expose underlying tissue to stomach acid

Heliobacter (diagnosis and management)

Urea breath test to check, then biopsy to confirm

Antacids, proton-pump inhibitors, heavy antibiotics to eradicate the organisms

No vaccine.

Klebsiella pneumoniae (properties)

Gram neg rod, lactose +, urease +, non-motile

Luxorious polysacchride capsule - major virulence factor

Respiratory pathogen

Ubiquitous in nature

Klebsiella pneumoniae (pathogenesis)

Adherence in lung leads to lung disease.

Inflammatory infiltrates, lung abscesses, necrotic destruction of alveolar spaces

Produces bloody sputum (currant like jelly)

Left shift of cells to fight infection, banded neutrophils

About this deck

By: Brian Nguyen
Created: 2011-02-04
Size: 28 flashcards
Views: 5

About StudyBlue

“I have been getting MUCH better grades on all my tests for school. Flash cards, notes, and quizzes are great on here. Thanks!”
Kathy