M05 - Enterobacteriacae and Biochemical Test Media

  1. A positive DNase test would be seen with

    B)  Serratia marcescens
  2. Which of the following growth characteristics is typical for Escherichia coli?

    C)  Beta-hemolytic on sheep blood agar (BAP)
  3. Which of the following organisms produce a positive phenylalanine deaminase reaction?

    A)  All of the above
  4. Identify the Gram-negative bacillus that can be described as:
    lactose: negative
    oxidase: negative
    indole: negative
    citrate: positive
    methyl red: positive
    urease: negative
    H S: positive
    clear colonies with black center on XLD

    B)  Salmonella enteritidis.
  5. Which species of Shigella is most commonly associated with diarrheal disease in the USA?

    A)  sonnei
  6. Shigella sp are genetically related to Escherichia coli but can easily be distinguished from each other using certain biochemical tests. List two biochemical tests you could perform to help you differentiate between these two organisms. Discuss the reactions you would expect to see for Shigella sp versus Escherichia coli for the biochemical tests you choose. *Note: ONE of your biochemical tests can be selective/differential plate media.
    Shigella can be differentiated from E.coli with HE agar plates. E. coli's ability to ferment lactose would produce acid and cause oranging of the agar while Shigella would not. Shigella from E. coli can also be differentiated using the TSI test as the shigella result would be K/A, alkaline over acid as it utilizes the peptones and E. coli would be A/A plus gas as it ferments the carb's producing acid and gas.
  7. A leg wound culture from a hospitalized 70-year-old diabetic man grew motile, lactose-negative colonies on MAC. Given the following biochemical reactions at 24 hours, what is the most probable organism?
    H S: negative
    Indole: negative
    MR/VP: negative/positive
    phenylalanine deaminase: negative
    DNase: positive
    citrate: positive
    urease: negative
    ornithine decarboxylase: positive
    lysine decarboxylase: positive
    arginine dehydrolase: negative
    Gelatin hydrolysis: negative

    C)  Serratia marcescens
  8. What amino acid is the substrate in indole test broth?

    D)  Tryptophan
  9. Which genera of Enterobacteriaceae are usually nonmotile at 35°C?

    D)  Shigella, Klebsiella, and Yersinia
  10. (T/F) The Moeller Decarboxylase Test requires an overlay of mineral oil to provide an anaerobic environment for decarboxylation, or hydrolysis of the amino acids to occur.
  11. Three blood cultures taken from a 30-year-old cancer patient receiving chemotherapy and admitted with a UTI grew "swarming" colonies of lactose-negative, motile, Gram-negative rods prior to antibiotic therapy. Given the following biochemical reactions, which is the most likely organism?
    H S: positive
    indole: negative
    MR/VP: positive/negative
    phenylalanine deaminase: positive
    DNase: negative
    citrate: positive
    urease: positive (rapid)
    gelatin hydrolysis: positive
    ornithine decarboxylase: positive

    A)  Proteus mirabilis
  12. A number of vacationers who traveled outside the U.S. have had their vacations interrupted by a case of "traveler's diarrhea," which is commonly associated with which etiologic agent?

    D)  Enterotoxigenic E. coli (ETEC)
  13. The medium used to determine whether an organism is oxidative or fermentative with respect to its metabolic activities is

    A)  OF medium
  14. Four blood cultures were taken over a 24-hour period from a 20-year-old woman with severe diarrhea. The cultures grew motile Gram negativerods. A urine specimen obtained by catheterization also showed Gram-negative rods, 100,000 col/mL. Given the following results, which is the most likely organism?
    TSI: A/A +gas
    Indole: positive
    MR/VP: positive/negative
    H S: negative
    citrate: negative
    urease: negative
    lysine decarboxylase: positive
    phenylalanine deaminase: negative

    A)  Escherichia coli
  15. (T/F) The purpose of the inverted Durham tube placed inside Carbohydrate Fermentation test tubes is to identify which organisms can grow anaerobically inside the Durham tube.
  16. Which test is used to presumptively identify verotoxin-producing Escherichia coli such as O157:H7.

    D) MUG
  17. The most appropriate biochemical test to differentiate between K. pneumoniae and K. oxytoca is

    A)  Indole
  18. Cefsulodin-irgasan-novobiocin (CIN) agar is recommended for the recovery of

    B)  Yersinia enterocolitica
  19. Which of the following organisms is considered an "anaerogenic biotype of E. coli?"

    A)  Shigella spp
  20. Which pathogen can exhibit the stain characteristics shown in the photograph
    Image Upload 1

    C)  Yersinia spp
  21. A foot wound from a nursing home patient was cultured and grew on MAC as pink to dark pink, oxidase-negative mucoid colonies. Further results were:
    Indole: negative
    MR/VP: negative/postiive
    Citrate: positive
    Urease: positive
    Motility: negative
    H S: negative

    The most likely organisms is:

    C)  Klebsiella pneumoniae
  22. Which of the following media and/or biochemical tests may be used to distinguish E.coli O157:H7 from commensal E.coli?

    D)  MAC and SMAC
  23. Plesiomonas shigelloides is a relatively new member of the Enterobacteriaceae. What characteristic separates it from other members of the Enterobacteriaceae?

    D)  it is oxidase positive
  24. A 64-year-old male with lymphoma has a positive blood culture at 18 hours incubation. The organism is a non-lactose fermenting Gram negative bacillus on MAC. Further testing gives the following reactions:
    ornithine decarboxylase=negative
    phenylalanine deaminase=positive

    The genus is:

    D)  Providencia
  25. Infection with the bubonic form of plague disease occurs by which route?

    A)  flea bite
  26. The Methyl Red test detects which end product of glucose fermentation?

    D)  mixed acids
  27. What substance is added to triple sugar iron (TSI) to detect the production of hydrogen sulfide gas?

    B)  Ferrous sulfate
  28. Match the statement from the left column with the best corresponding organism(s) in the right column.

    +Enterotoxigenic E. coli (ETEC)
    +Shigella infection
    +Salmonella enterica ss typhi
    +Enterohemorrhagic E. coli (EHEC)
    +Klebsiella spp.
    +Uropathogenic E. coli

    -Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
    -Scant stool with blood, mucus and pus
    -Traveler's diarrhea
    -Major nosocomial pathogen; non-motile
    -Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
    -Associated with eggs, dairy products, and cold-blooded animals
    -Iron chelation
    • Enterotoxigenic E. coli (ETEC): Traveler's diarrhea
    • Shigella infection: Scant stool with blood, mucus and pus
    • Salmonella enterica ss typhi: Associated with eggs, dairy products, and cold-blooded animals
    • Enterohemorrhagic E. coli (EHEC): Can lead to hemolytic uremic syndrome (HUS), produces Shiga toxin
    • Klebsiella spp.: Major nosocomial pathogen; non-motile
    • Uropathogenic E. coli: Iron chelation
  29. Which of the pathogenic E.coli is known for its stacked brick colony formation on the intestinal mucosa?

    C) EAEC
  30. Yersinia pestis is characteristically

    A)  Urease negative
  31. Which of the following organisms would produce a yellow slant and a yellow butt plus gas on TSI agar after incubating 18 hours?

    B)  Escherichia coli
  32. The K antigen of the family Enterobacteriacea is

    C)  Heat labile
  33. The majority of clinical isolates of Klebsiella are

    A)  K. pneumoniae
  34. Which of the following is not true of Shigella?

    A)  Large numbers of organisms must be ingested to produce disease.
  35. Hemolytic uremic syndrome is a complication after infection with

    C)  E. coli O157:H7
  36. Which member of the Enterobacteriaceae is a causative agent of caseous swellings called pseudotubercules?

    D)  Yersinia pseudotuberculosis
  37. One of the most common etiologic agents of community-acquired uncomplicated cases of cystitis is

    A)  Escherichia coli
  38. Reptiles kept as pets are sometimes associated with the transmission of

    D)  Salmonella
  39. (T/F) These organisms are always considered pathogens, not commensal organisms, when they are isolated from patient specimens: Salmonella, Shigella, Yersinia.
  40. Which test is performed on isolates of Klebsiella pneumoniae to identify if the isolate is a potential cause of pyogenic liver abscesses

    B)  String test
Card Set
M05 - Enterobacteriacae and Biochemical Test Media
M05 - Enterobacteriacae and Biochemical Test Media