Diarrhea Bacteria Flashcards
Escherchia coli
Diarrhea •Gr (-) Rod •Facultative anaerobe •*Oxidase (-) •*Ferment lactose •Live in the intestines of humans and other animals, found in feces •Highly motile •causes Gastroenteritis, dysentery, HUS, urinary tract infections, septicemia, & neonatal meningitis/sepsis
enterotoxogenic E. coli
ETEC
Diarrhea •adults, children •Worldwide •Sudden onset *watery diarrhea for 3-5 days •Ingestion of contaminated food or water; associated with travel in U.S. = “**Traveler’s diarrhea” •Fecal-oral transmission (all) •Adhere to jejunum & ileum by pili Virulence •pili •Heat-labile toxin (LT) •Heat-stabile toxin (ST)
enteropathogenic E. coli
EPEC
Diarrhea
•Infants
•Fecal-oral transmission
•Main reservoir: humans
Disease
-produces *watery diarrhea
•Potentially fatal diarrhea for infants in developing countries
Virulence
-has *bundle-forming pili
•Forms *“attaching and effacing lesions” on enterocytes in the small intestines that destroy the microvilli
•Uses host cell *actin to form *pedestals beneath site of attachment → watery diarrhea
enteroagreggative E. coli
EAEC
Diarrhea
•watery diarrhea that may be accompanied by mucus or blood
•persistent diarrhea in young children
•chronic diarrhea in immunocompromised
•Colonize the mucosa of small and large intestines
Virulence
•aggregative adhesion fimbriae (AAF) to form a unique biofilm
•cytotoxins & enterotoxins
enterohemorrhagic E. coli
EHEC
Diarrhea
•effects young children, the elderly & immunosuppressed
•Fecal-oral transmission
•Main reservoir: cattle
•Most infections due to ground beef & beef products, and produce
•*bloody diarrhea, hemorrhagic colitis, hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura
•Colonize the distal ileum & large bowel in humans
Virulence
•produces *Shiga toxin
•pili
•pedestal
enteroinvasive E. coli
EIEC
Diarrhea •Primarily seen in children -fecal-oral transmission •Main reservoir: humans Disease -*“mild bacillary dysentery”; watery diarrhea, bloody diarrhea Virulence -enterotoxin
Vibrio cholera
Diarrhea •Gr (-) curved rod, comma shaped •*Oxidase (+) •*ferments sucrose •MacConkey – colorless •Reservoir: Marine environments •Colonizes small intestine Disease -causes *"rice-water stool" Virulence •*O1-biotype •O139-capsule •flagella •pili •*mucinase •*cholera toxin
V. parahemolyticus
Diarrhea
•Ingestion of raw or undercooked seafood (eg, oysters), very common in Japan
•Causes watery diarrhea, abdominal cramps, fever for ~3 days; self-limited
•Hemolysins act like CT; grows on 8% NaCl; green colonies on TCBS agar
V. vulnificus
Diarrhea
•A marine organism (likes Gulf of Mexico & oysters); grows on 8% NaCl; green colonies on TCBS agar
•Cause gastroenteritis if healthy, cellulitis (especially for shellfish handlers)
•Potentially fatal wound infections or septicemia for immunocompromised; treat with doxycycline
Shigella species
Diarrhea -Slender, non-motile gram-negative rods -Facultative anaerobes -Fecal-oral transmission -Associated with crowded & unsanitary conditions, MSM -ass. fruits & vegetables Disease -causes shingellosis aka *bacillary dysentery -causes "current jelly" stool Labs -Non-lactose fermenting -No H2S or gas production -MacConkey agar & EMB -Selective growth on Hektoen enteric (HE) agar or Salmonella–Shigella (SS) agar Virulence -produce *shiga toxin
Salmonella species
Diarrhea
-Motile, gram-negative rods
-Facultative anaerobes
-fecal-oral transmission
-Reservoir: Humans only
-May colonize the gastrointestinal tracts of mammals, reptiles & birds including their eggs
-Risk factors: more severe if very young or very old or HIV-positive
Disease
-causes Typhoid fever and Salmonellosis (gastroenteritis)
Labs
- Non-lactose fermenting
-Produces H2S & gas
-Grows on MacConkey agar & EMB
-Selective growth on Hektoen enteric (HE) agar or Salmonella–Shigella (SS) agar
Virulence
-Survive at the low pH of the stomach
-Evade multiple defenses of the small intestine
-Preferentially enter M cells by inducing “membrane ruffling”
-Resistance to bile salts
-Produces Vi, an antiphagocytic capsular antigen
Campylobacter jejuni
Diarrhea
-Curved gram-negative rod
-often in pairs look like “seagulls” or are S-shaped
-Main reservoir: domestic animals
-Transmission: fecal-oral
-More common in the summer
-Also, associated with travel
Disease
-Begins with foul-smelling watery diarrhea, then bloody diarrhea with fever; nausea, vomiting, severe abdominal pain (mimics appendicitis), headache; self-limited
-Bacteremia leading to meningitis, hepatitis, cholecystitis, pancreatitis, septic abortion
-Reactive arthritis
-Antecedent to *Guillain-Barré syndrome
Labs
-Microaerophilic
-Grows at 42°C; thermophilic
-Non-spore forming
-Do not break down carbohydrates, so amino acids & metabolic intermediates are used for energy
-Oxidase-positive & catalase-positive
Yersinia enterocolitica
Yersinia pseudotuberculosis.
Diarrhea
- Pleomorphic gram-negative bacilli; can look like coccobacilli
- Bipolar staining; “safety pins”
- Facultative anaerobe
- Primarily animal pathogens
- Intestinal tracts of pigs, dogs, cats, rodents, rabbits, sheep, horses & cattle
- Transmission: Fecal-oral
- Most important sources are pigs & pig products
- More common in Europe than the U.S.
- Disease more common in children
Clostridium difficile
Diarrhea •Gr+ rod •ubiquitous •obligate anaerobe •leading cause antibiotic-associated diarrhea hospitals, long-term care facilities -creates *pseudomembranes Risk Factors CDAD •**antibiotic use!!! •hospitalization •advanced age •severe illness Virulence •*endospores •(+) flagella •*toxin A (enterotoxin) •*toxin B (cytotoxin) Disease -Clostridium difficile-associated diarrhea (CDAD) •diarrhea with colitis o**WATERY DIARRHEA, foul-smelling ocan have 10-15X/day olower abdominal pain, cramping, low grade fever, leukocytosis •**pseudomembranous colitis= above plus pseudomembranes •fulminant colitis Diagnosis -*PCR of stool -*stool ELISA Tx •discontinue implicated antibiotic •fluid replacement •metronidazole to vancomycin or fidaxomicin •*FECAL TRANSPLANT
