Enterobacteriaceae II Flashcards
E. Coli diseases (non-diarrheal)
UTI, pneumonia, bacteremia
Klebsiella
Diseases
Capsule type
Ampicillin susceptiblity
Often seen in what type of patient?
Multiple nosocomial infections (biliary infection, peritonitis, wound infection, UTI, pneumonia)
Mucoid capsule
Resistant to ampicillin - has beta-lactamase
Alcoholics
What does sputum of someone with Klebsiella pneumoniae infection look like?
Currant-jelly
Associated with long-term use of urinary catheters
Produces urease, causing crystal formation
Highly motile and forms biofilms
Proteus mirabilis
What cousins of Proteus also cause urinary infection due to long-term catheters?
Morganella, Providencia
Enterobacter - opportunistic pathogen
Endogenous location?
Lactose fermentation
Antimicrobial resistance
- Intestinal flora
- Ferments lactose
- Highly resistant - B-lactamase, high mutation rate, plasmids
What is disk approximation test?
Plate has cefoxitin disk as well as a 2nd antibiotic disk. Streak plate with organism resistant to cefoxitin.
If growth around cefoxitin is smaller than around 2nd disk, antagonism (inducible resistance) has occurred.
Serratia marcescens - opportunistic pathogen
- Colony color
- Location in environment
- Types of patients it infects
- Diseases
- Red
- Water
- Nosocomial, IV drug users
- Endocarditis, osteomyelitis
Citrobacter
Diseases
Catheter-associated UTI
C. diversus: brain abscess in neonates
Enterotoxigenic E. Coli (ETEC)
Diseases
Prevention/Treatment
Watery, non-inflammatory diarrhea
Leading cause of travelers’ diarrhea and leading cause of mortality among young children in developing countries
Prevent: Boil, cook, peel
Treat: Bismuth subsalicylate, antibiotics are effective but not necessary
Pathogenesis by ETEC strains
- Fimbriae adhere to intestinal mucosa
- Releases enterotoxins:
- Heat stable (ST) increases cGMP
- Heat labile (LT) incrases cAMP
- Both act on CFTR to cause secretion of chloride into lumen
What is an enterotoxin?
Exotoxin that acts upon GI epithelia to increase fluid secretion
Enterohemorrhagic E. coli (EHEC)
Diseases Toxin/Pathogenesis Reservoir Most important clone Lab Diagnosis Treatment
- Bloody and watery diarrhea, abdominal cramping, HUS (hemolytic uremic syndrome)
- Shiga toxin - destroys ribosomal protein synthesis
- Stx1 and Stx2 (encoded on bacteriophage)
- LEE pathogenicity island
- Attaching and effacing, loss of microvilli
- GI tract of cattle/large herbivores
- O157:H7
- Lab diagnosis: culture on sorbitol-MAC, PCR, enzyme immunoassay
- Treatment: supportive, antibiotics are contraindicated
What are schistocytes?
RBC’s that have been sheared apart and fragmented
What three things are seen in HUS/hemolytic uremic syndrome?
Renal failure, hemolytic anemia, thrombocytopenia
