BOC Microbiology exam Study test2| Questions
with Revised Answers| Verified 100% Correct
A specimen from a 15 year old burn patient was cultured after debridement, and the
following results were obtained:
=========================================
Oxidase pos, Catalase pos, Ornithine neg, Arg pos, Penicillin res, Lysine neg, Motility pos,
Glucose pos (open tube), Maltose neg (open tube), aminoglycosides susceptible,
colistin(polymixin b) susceptible. - ✔✔Pseudomonas aeruginosa ( Acinetobacter spp.
is oxidase negative and Moraxella spp. are highly susceptible to penicillin)
A yellow pigment-producing organism that is oxidase positive, nonmotile, and does not
grow on MacConkey agar is? - ✔✔Chryseobacterium meningosepticum (Oxidase
positive, yellow pigment, and do not grow on Mac agar.)
Which reagent(s) is (are) used to develop the red color indicative of a positive reaction
in the nitrate reduction test? - ✔✔Sulfanilic acid and Alpha-naphthylamine
A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar
that gave the following results:
========================================
Oxidase pos, KIA= K/K(H2S pos), Nitrate reduction pos, Motility pos single polar
flagellum, ornithine decarb pos, DNase pos, Growth at 42C neg. - ✔✔Shewanellae
putrefaciens (S. putrefaciens produces abundant H2S on KIA or TSI. Shewanellae are the
only nonfermenters that produce H2S on these media
Chryseobacterium spp. and B. cepacia are easily differentiated by which test? -
✔✔Motility (B. cepacia(93%) are weakly oxidase positive and motile.
chryseobacterium spp. are oxidase positive but are nonmotile)
, A 15-year old female complained of a severe eye irritation after removing her soft-
contact lenses. A swab of the infected right eye was obtained by an opthamalmologist,
who ordered a culture and sensitivity test. The culture was plated on blood agar and
MacConkey agar. At 24 hours, growth of a gram-negative rod that tested positive for
cytochrome oxidase was noted. The Mueller-Hinton sensitivity plate showed a bluish
green "lawn" of growth that proved highly resistant to most of the antibiotics tested
except amikacin, tobramycin, and ciprofloxacin. What is the most likely identification? -
✔✔Pseudomonas aeruginosa
Which of the listed Pseudomonas spp. is associated with the following virulence factors:
exotoxin A, endotoxins, proteolytic enzymes, antimicrobial resistance, and production of
alginate? - ✔✔Pseudomonas aeruginosa
A 20-year old horse groomer exhibited a "glanders-like" infection. His history indicated
he had suffered several open wounds on his hands 2 weeks beforethe swelling of his
lymph nodes. A gram-negative rod was recovered from a blood coulture that grew well
on blood and Mac agars. Most of the biochemical tests were negative, including the
cytochrome oxidase test. What is the most likely identification? - ✔✔Burkholderia
mallei (a causative agent in mules, donkeys and horses)
A vietnam war veteran presented with "glanders-like" infection (melioidosis). Several
blood cultures produced gram-negative rods that were positive for cytochrome oxidase ,
oxidized glucose and xylose, and grew at 42C. What is the most likely organism? -
✔✔Burkholderia pseudomallei (Latent stages often seen, and may surface years
later. Infections often produce abscess in organs (liver, spleen, lungs) as well as on the
skin, in soft tissue, and in joints and bones.)
Cytochrome oxidase-positive, nonfermentative gram negative bacilli were recovered
from teh stool of a cystic fibrosis (CF) patient. The isolates produced wet (mucoidy)
colonies on blood agar. Which identification is most likely? - ✔✔Pseudomonas
aeruginosa (P. aeruginosa produces alginate that accounts for the "wet, mucoidy"
appearance of colonies. This overproduction of alginate is thought to cause the
inhibition of phagocytosis.
with Revised Answers| Verified 100% Correct
A specimen from a 15 year old burn patient was cultured after debridement, and the
following results were obtained:
=========================================
Oxidase pos, Catalase pos, Ornithine neg, Arg pos, Penicillin res, Lysine neg, Motility pos,
Glucose pos (open tube), Maltose neg (open tube), aminoglycosides susceptible,
colistin(polymixin b) susceptible. - ✔✔Pseudomonas aeruginosa ( Acinetobacter spp.
is oxidase negative and Moraxella spp. are highly susceptible to penicillin)
A yellow pigment-producing organism that is oxidase positive, nonmotile, and does not
grow on MacConkey agar is? - ✔✔Chryseobacterium meningosepticum (Oxidase
positive, yellow pigment, and do not grow on Mac agar.)
Which reagent(s) is (are) used to develop the red color indicative of a positive reaction
in the nitrate reduction test? - ✔✔Sulfanilic acid and Alpha-naphthylamine
A culture from an intra-abdominal abscess produced orange-tan colonies on blood agar
that gave the following results:
========================================
Oxidase pos, KIA= K/K(H2S pos), Nitrate reduction pos, Motility pos single polar
flagellum, ornithine decarb pos, DNase pos, Growth at 42C neg. - ✔✔Shewanellae
putrefaciens (S. putrefaciens produces abundant H2S on KIA or TSI. Shewanellae are the
only nonfermenters that produce H2S on these media
Chryseobacterium spp. and B. cepacia are easily differentiated by which test? -
✔✔Motility (B. cepacia(93%) are weakly oxidase positive and motile.
chryseobacterium spp. are oxidase positive but are nonmotile)
, A 15-year old female complained of a severe eye irritation after removing her soft-
contact lenses. A swab of the infected right eye was obtained by an opthamalmologist,
who ordered a culture and sensitivity test. The culture was plated on blood agar and
MacConkey agar. At 24 hours, growth of a gram-negative rod that tested positive for
cytochrome oxidase was noted. The Mueller-Hinton sensitivity plate showed a bluish
green "lawn" of growth that proved highly resistant to most of the antibiotics tested
except amikacin, tobramycin, and ciprofloxacin. What is the most likely identification? -
✔✔Pseudomonas aeruginosa
Which of the listed Pseudomonas spp. is associated with the following virulence factors:
exotoxin A, endotoxins, proteolytic enzymes, antimicrobial resistance, and production of
alginate? - ✔✔Pseudomonas aeruginosa
A 20-year old horse groomer exhibited a "glanders-like" infection. His history indicated
he had suffered several open wounds on his hands 2 weeks beforethe swelling of his
lymph nodes. A gram-negative rod was recovered from a blood coulture that grew well
on blood and Mac agars. Most of the biochemical tests were negative, including the
cytochrome oxidase test. What is the most likely identification? - ✔✔Burkholderia
mallei (a causative agent in mules, donkeys and horses)
A vietnam war veteran presented with "glanders-like" infection (melioidosis). Several
blood cultures produced gram-negative rods that were positive for cytochrome oxidase ,
oxidized glucose and xylose, and grew at 42C. What is the most likely organism? -
✔✔Burkholderia pseudomallei (Latent stages often seen, and may surface years
later. Infections often produce abscess in organs (liver, spleen, lungs) as well as on the
skin, in soft tissue, and in joints and bones.)
Cytochrome oxidase-positive, nonfermentative gram negative bacilli were recovered
from teh stool of a cystic fibrosis (CF) patient. The isolates produced wet (mucoidy)
colonies on blood agar. Which identification is most likely? - ✔✔Pseudomonas
aeruginosa (P. aeruginosa produces alginate that accounts for the "wet, mucoidy"
appearance of colonies. This overproduction of alginate is thought to cause the
inhibition of phagocytosis.
