DIAGNOSTIC BACTERIOLOGY :A STUDY GUIDE 2024-2025
|COMPLETE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS ) A GRADE.
The gram stain of a lemon-yellow colony shows gram-positive cocci
in tetrads. This organism is most likely: - ANSWER-Micrococcus spp.
A nasal swab is inoculated onto MSA plate and incubated overnight at
35 C. An examination of the plate shows numerous colonies on yellow
agar. This culture is most likely to contain: - ANSWER-S. aureus
Which of the following media are appropriate for culturing
coagnegative staph? - ANSWER-blood agar and CNA
A GPC from a urine culture gives the following reactions:
Catalase: positive
Staph latex agglutination: negative
The technologist should: - ANSWER-Perform a novobiocin
susceptibility
The disease that S. saprophytic most often causes is: - ANSWER-UTI
A GPC gives the following reactions:
Catalase: bubbles
Slide coagulase: clumps in saline
Clumps when plasma is added
The technologist should: - ANSWER-Perform tube coagulase
,A GPC gives the following reactions:
Catalase: bubbles
Bacitracin: small zone of inhibition
Furazolidone: no zone of inhibition
Modified oxidase: blue color
The technologist should now: - ANSWER-ID and report the organism
as Micrococcus spp.
A technologist performs a thermonuclear test on a staph isolate as
follows:
1. A drop of broth culture is placed on a DNAse agar well
2. The plate is incubated for 2 hours at 35 C
3. A pink halo is present in the agar surrounding the well
The technologist should: - ANSWER-Repeat the test; boil the broth
culture for 15 min
The reagent used to differentiate streptococci from staphylococci is: -
ANSWER-hydrogen peroxide
The CAMP test is performed by streaking group B streptococci
perpendicular to a streak of: - ANSWER-S. aureus
The streptococcus that most often causes newborn infections:
(biochemical ID) - ANSWER-hydrolyzes hippurate
A beta-hemolytic streptococci gives the following reactions:
,CAMP: positive
Bacitracin: susceptible
The technologist should: - ANSWER-Perform a Lancefield grouping
test
A physician submits a throat specimen for a rapid antigen test for a
group A Streptococci. The latex agglutination test shows no
clumping. The technologist should now: - ANSWER-report the results
as negative and set up a throat culture
A gamma-hemolytic streptococcus gives the following reactions:
Bile-esculine: black
Optochin: growth occurs up to disk
The technologist should: - ANSWER-perform a 6.5% salt-tolerance
test
What nutrients are required by satelliting streptococci? - ANSWER-
Thiol, Vitamin B6, Pyridoxal
Which of the following are alpha-hemolytic?
Group A streptococcus, Viridans streptococcus, Nonenterococcal
group D streptococcus, S. pneumoniae - ANSWER-Viridans strep,
nonenterococcal group D strep, S. pneumoniae
T or F: Streptococci usually require CO2 to grow - ANSWER-false
, T or F: Leuconostoc spp. are resistant to vancomycin - ANSWER-True
When a catalase test was performed on a Lab's QC strain of
Lactobacillus, no bubbles appeared after 15 seconds. The technologist
should: - ANSWER-accept the results
The laboratory received a specimen labeled "pharyngeal
pseudomembrane". This specimen should be inoculated onto: -
ANSWER-Blood agar, Loeffler medium, and Cystine-Tellurite agar
The biochemical tests performed on a gram-positive rod were
consistent with C. diphtheria. The technologist should now: -
ANSWER-Perform an Elek test to determine if the isolate is toxigenic
An 18 Hour old culture of an infant's cerebrospinal fluid had the
following characteristics:
Blood agar: growth (colonies surrounded by clear zones)
Chocolate agar: growth
Gram stained smear: blue/purple coccobacilli
Catalase: positive
Test appropriate for identifying the organism are: - ANSWER-
Bileescule and motility
A hog farmer complaining of red sores on his hands was seen by his
physician. One of the lesions was biopsied and cultured. The culture
grew an organism with the following characteristics:
Hemolysis: gamma
Catalase: negative
|COMPLETE QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS ) A GRADE.
The gram stain of a lemon-yellow colony shows gram-positive cocci
in tetrads. This organism is most likely: - ANSWER-Micrococcus spp.
A nasal swab is inoculated onto MSA plate and incubated overnight at
35 C. An examination of the plate shows numerous colonies on yellow
agar. This culture is most likely to contain: - ANSWER-S. aureus
Which of the following media are appropriate for culturing
coagnegative staph? - ANSWER-blood agar and CNA
A GPC from a urine culture gives the following reactions:
Catalase: positive
Staph latex agglutination: negative
The technologist should: - ANSWER-Perform a novobiocin
susceptibility
The disease that S. saprophytic most often causes is: - ANSWER-UTI
A GPC gives the following reactions:
Catalase: bubbles
Slide coagulase: clumps in saline
Clumps when plasma is added
The technologist should: - ANSWER-Perform tube coagulase
,A GPC gives the following reactions:
Catalase: bubbles
Bacitracin: small zone of inhibition
Furazolidone: no zone of inhibition
Modified oxidase: blue color
The technologist should now: - ANSWER-ID and report the organism
as Micrococcus spp.
A technologist performs a thermonuclear test on a staph isolate as
follows:
1. A drop of broth culture is placed on a DNAse agar well
2. The plate is incubated for 2 hours at 35 C
3. A pink halo is present in the agar surrounding the well
The technologist should: - ANSWER-Repeat the test; boil the broth
culture for 15 min
The reagent used to differentiate streptococci from staphylococci is: -
ANSWER-hydrogen peroxide
The CAMP test is performed by streaking group B streptococci
perpendicular to a streak of: - ANSWER-S. aureus
The streptococcus that most often causes newborn infections:
(biochemical ID) - ANSWER-hydrolyzes hippurate
A beta-hemolytic streptococci gives the following reactions:
,CAMP: positive
Bacitracin: susceptible
The technologist should: - ANSWER-Perform a Lancefield grouping
test
A physician submits a throat specimen for a rapid antigen test for a
group A Streptococci. The latex agglutination test shows no
clumping. The technologist should now: - ANSWER-report the results
as negative and set up a throat culture
A gamma-hemolytic streptococcus gives the following reactions:
Bile-esculine: black
Optochin: growth occurs up to disk
The technologist should: - ANSWER-perform a 6.5% salt-tolerance
test
What nutrients are required by satelliting streptococci? - ANSWER-
Thiol, Vitamin B6, Pyridoxal
Which of the following are alpha-hemolytic?
Group A streptococcus, Viridans streptococcus, Nonenterococcal
group D streptococcus, S. pneumoniae - ANSWER-Viridans strep,
nonenterococcal group D strep, S. pneumoniae
T or F: Streptococci usually require CO2 to grow - ANSWER-false
, T or F: Leuconostoc spp. are resistant to vancomycin - ANSWER-True
When a catalase test was performed on a Lab's QC strain of
Lactobacillus, no bubbles appeared after 15 seconds. The technologist
should: - ANSWER-accept the results
The laboratory received a specimen labeled "pharyngeal
pseudomembrane". This specimen should be inoculated onto: -
ANSWER-Blood agar, Loeffler medium, and Cystine-Tellurite agar
The biochemical tests performed on a gram-positive rod were
consistent with C. diphtheria. The technologist should now: -
ANSWER-Perform an Elek test to determine if the isolate is toxigenic
An 18 Hour old culture of an infant's cerebrospinal fluid had the
following characteristics:
Blood agar: growth (colonies surrounded by clear zones)
Chocolate agar: growth
Gram stained smear: blue/purple coccobacilli
Catalase: positive
Test appropriate for identifying the organism are: - ANSWER-
Bileescule and motility
A hog farmer complaining of red sores on his hands was seen by his
physician. One of the lesions was biopsied and cultured. The culture
grew an organism with the following characteristics:
Hemolysis: gamma
Catalase: negative
