Aerobic Gram Negative Bacteria

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  1. Most species of Enterobacteriaceae are normal flora to the GI tract, what species are NOT?
    • Salmonella
    • Shigella
    • Yersinia
  2. What clinical conditions are associated with Enterobacteriaceae?
    • Nosocomial infections
    • UTIs
    • Gastroenteritis
    • Septicemia
    • Food poisoning
    • Wound infections
    • Peritonitis
    • Pneumonia
    • Meningitis
  3. What 4 serological characteristics does the Enterobacteriaceae exhibit?
    • O (somatic) antigen - cell wall antigen (heat stable)
    • K (envelope) antigen - Capsular antigen (heat labile)
    • H (flagellar) antigen - Flagellar antigen (heat labile)
    • Vi antigen - Capsular antigen of Salmonella Typhi (heat labile)
  4. What tests and results are performed to identify Enterobacteriaceae (as a family)?
    • Facultative anaerobes
    • Ferment glucose
    • Nitrate - POS
    • Catalase - POS
    • Oxidase - NEG
  5. Name some enteric media
    • MAC - to differentiate lactose fermenters
    • EMB (eosin-methylene blue) - to differentiate lactose fermenters
    • HE (hektoen enteric) - lactose and sucrose fermenters
    • XLD (xylose-lysine- desoxycholate) - lactose and sucrose fermenters
    • SS (Salmonella-Shigella) - Lactose fermenters
    • Bismuth sulfite - lactose fermenters and Salmonella typhi
    • Brilliant green - for growth of non-lactose fermenters
    • Selenite broth - enhancement medium for stool, salmonella is enhanced, prohibits gram positive and normal flora
  6. What are the clinical conditions associated with E. coli?
    • UTIs
    • Appendicitis
    • Peritonitis
    • Gallbladder infections
    • Endocarditis
    • Meningitis in newborans
    • Gasteroenteritis
    • Food poisoning
  7. What bacteria:
    IMViC  ++--
    Lactose fermenter
    Motility - POS
    ONPG - POS
    H2S - NEG
    Urease - NEG
    TSI - A/A (Acid over Acid)
  8. What clinical conditions does Enterohemorrhagic E. coli (EHEC) cause?
    • Hemorrhagic colitis
    • Hemolytic uremic syndrome (HUS)
    • Leads to kidney failure in young children
  9. How is Enterohemorrhagic E. coli (EHEC) spread?
    • Eating undercooked hamburger
    • Eating/Drinking contaminated foods like apple cider, basil, sprouts
  10. What is the principall virulence factor in Enterohemorrhagic E. coli and how does it work?
    • Shiga toxin (Stx) 1 and 2
    • Many belong to the group O157:H7
  11. What tests and results are performed to identify E. coli O157:H7?
    • Growth of colorless colonies on SMAC (sorbitol-MacConkey)
    • Confirmatory testing is by detection of Stx-1 and Stx-2
  12. What clinical condition does Enterotoxigenic E. coli (ETEC) cause?
    Severe epidemic diarrhea
  13. What clinical conditions are caused by Enteroinvasive E. coli (EIEC)
    Bloody diarrhea by invading the intestinal epithelium
  14. What clinical condition is caused by Enteropathogenic E. coli (EPEC)?
    Watery diarrhea
  15. What clinical conditions are associated with Shigella?
    • Shigellosis - form of bacterial dysentery, with abdominal pain, fever, and diarrhea
    • Infections - in children and elderly
    • Food poisoning - by direct fecal contamination
  16. What is the incubation period for Shigella?
    1-7 days
  17. What are the 4 serogroups of Shigella, based on O antigens?
    • S. dysenteriae (serogroup A)
    • S. flexneri (serogroup B)
    • S. boydii (serogroup C)
    • S. sonnei (serogroup D)
  18. What clinical conditions are associated with Shigella dysenteriae?
    • Enterotoxin - affects the large intestines
    • Neurotoxin - may result in paralysis
  19. What bacteria:
    Associated with Produces mild diarrhea and Shigellosis (most common cause)
    Mannitol Positive 
    ONPG Positive (delayed lactose fermenter)
    TSI - Alkaline over acid (K/A)
    IMViC ++--
    H2S - NEG
    Motility - NEG
    Urease - NEG
    Lactose - NEG
    Shigella sonnei
  20. What bacteria:
    Associated with mild diarrhea
    Mannitol Positive 
    ONPG Negative
    TSI - Alkaline over acid (K/A)
    IMViC ++--
    H2S - NEG
    Motility - NEG
    Urease - NEG
    Lactose - NEG
    • Shigella dysenteriae
    • Shigella flexneri
    • Shigella boydii
  21. What bacteria:
    Associated with UTIs, Pneumonia, Nosocomial infections, Klebsiella pneumonia
    TSI - A/A (Acid over acid) with gas
    MAC plate - pink colonies that are mucoid due to capsule production
    IMViC  --++
    H2S - NEG
    Lactose Positive
  22. What bacteria
    The causative agent of ganuloma inguinale
    Sexually transmitted disease
    Does not Gram stain or grow on laboratory media
    Use Wright or Giemsa stains - Donovan bodies may be seen (intracellular pleomorphic bipolar staining bacterial cells)
    Klebsiella (Calymmatobacterium) granulomatis
  23. What are the most common and Enterobacter species?
    • Enterobacter cloacae (most common)
    • Enterobacter aerogenes (2nd most common)
  24. What bacteria:
    Associated with Respiratory tract infections, Wound infections, Blood infections
    IMViC --++
    H2S - NEG
    Lactose - POS (except E. taylorae)
    E. aerogenes - arginine negative and lysine positiveE. cloacae - arginine positive and lysine negative
  25. What is the most common clinical isolate of Serratia?
    Serratia marcescens
  26. What bacteria:
    Associated with Opportunisitic infections in chemotherapy and immunocompromised patients
    IMViC ++--
    DNase - POS
    Gelatinase - POS
    Lipase - POS
    ONPG - POS (delayed lactose fermenter)
  27. How is Salmonella spread?
    • Contaminated water
    • Undercooked food (especially chicken)
  28. What clinical conditions are associated with Salmonella typhi?
    Typhoid fever - septicemia followed by a GI tract infection
  29. What bacteria:
    Associated with Moderate to severe gastroenteritis and Salmonellosis (due to serotypes belonging to the species S. enterica)
    IMViC -+-+
    H2S - POS
    Motility - POS
    Urease - NEG
    Lactose - NEG
    Colonies on HE agar are green with black centers
  30. What are the most common isolates of Proteus?
    • Proteus vulgaris
    • Proteus mirabilis
  31. What bacteria:
    IMViC ++-+
    H2S - POS
    Urease - POS
    TDA (tryptophan deaminase) - POS
    PDA (phenylalanine deaminase) - POS
    ONPG - NEG
    Lactose - NEG
  32. What bacteria:
    Causes plague
    Potential bioterrorism agent
    Transmitted by fleas
    Yersinia pestis
  33. What bacteria:
    Spread by drinking contaminated water or eating meat
    Yersinia enterocolitica
  34. What bacteria:
    IMViC -+--
    Urease - POS
    ONPG - POS
    Delayed lactose fermenter
    Sucrose - POS
    TSI - A/A (Acid over acid)
    Yersinia enterocolitica
  35. What clinical condition is associated with Yersinia pseudotuberculosis?
    Lymphadenitis in children
  36. What medium is selective for Yersinia enterocolitica?
    Cefsulodin-irgasan-novobiocin (CIN) medium
  37. What bacteria:
    IMViC -+--
    Urease - NEG
    Mot - NEG
    Oxidase - NEG
    Yersinia pestis
  38. What is the most common isolate for Edwardsiella?
    E. tarda
  39. What bacteria
    IMViC ++--
    H2S - POS
    ONPG - NEG
  40. What is the most common species isolated for Citrobacter?
    Citrobacter freundii
  41. What bacteria:
    IMViC -+-+
    Indole POS
    Mannitol POS
    Citrobacter diversus
  42. What bacteria:
    IMViC -+-+
    Indole NEG
    Mannitol NEG
    H2S POS
    C. freundii
  43. What bacteria:
    Indole - POS
    VP - NEG
    Citrate - NEG
    PDA - POS
    TDA - POS
    Morganella morganii
  44. What is the most common isolate for Providencia?
    Providencia rettgeri
  45. What bacteria:
    PDA - POS
    TDA - POS
    Indole - POS
    Citrate - POS
    VP - NEG
Card Set:
Aerobic Gram Negative Bacteria
2013-05-13 03:16:21

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