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Clinical Bacteriology > 1st Unit > Flashcards

1st Unit Flashcards

1
Q

Which of the following is true about jumping genes?
A. RNA sequences that jump from one location of the chromosome to another
B. all of the choices
C. always carry essential genes; required for bacterial replication
D. may either be a transposon or an insertion sequence
E. circular piece of DNA that is not part of the chromosome

A

D

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2
Q

The following factors will reduce the effectivity of disinfection, EXCEPT…
A. long contact time
B. presence of biofilm
C. high amounts of mucus and blood
D. high numbers of microorganisms

A

A

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3
Q

Which of the following is the best course to keep stock cultures in the log phase of the growth curve?
A. incubation at room temperature
B. transfer to a fresh medium
C. refrigeration
D. incubation at 40oC

A

B

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4
Q

Which of the following is not true when performing antibiotic susceptibility tests?
A. MH agar must be supplemented when testing fastidious bacteria
B. the inoculum must be standardized prior to use
C. the log phase inoculum is recommended for highly fastidious bacteria
D. MICs are not routinely reported

A

C

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5
Q

Which of the following is true about conjugation?
A. It is a form of asexual reproduction
B. The process is mediated by a bacteriophage
C. It can transfer either chromosomal or plasmid DNA
D. It is a form of mutation
E. all of the choices

A

C

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6
Q

Which of the following is the most commonly used method for producing isolated colonies from clinical samples?
A. pour plate method
B. streak plate method
C. spread plate method

A

B

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7
Q

There is no bacteria replication occurring during the stationary phase
A. True
B. False

A

B

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8
Q

The following are media that are both selective and enriched, EXCEPT…
A. Martin Lewis agar
B. Lowenstein-Jensen medium
C. Chocolate agar
D. Selenite-F broth

A

C

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9
Q

When a D-zone test is positive, the susceptibility test result must report…
A. resistance to both erythromycin and clindamycin
B. susceptibility to both gentamycin and clindamycin
C. resistance to clindamycin and susceptibility to gentamycin
D. resistance to both erythromycin and gentamycin

A

A

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10
Q

Which of the following is a task performed on day 2 of a routine culture and susceptibility test?
A. direct microscopic exam
B. selection of primary culture media
C. interpretation of susceptibility test
D. inoculum preparation

A

D

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11
Q

The following combination will allow the isolation of both fastidious and non-fastidious Gram-negative bacilli.
A. Mannitol Salt Agar and PEA Blood agar
B. Chocolate agar and Eosin Methylene Blue agar
C. MacConkey agar and Lowenstein-Jensen medium
D. EMB agar and Thayer-Martin agar

A

B

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12
Q

When evaluating the adequacy of a sputum sample, the presence of the following indicates active infection, EXCEPT…
A. mucus
B. bacteria
C. neutrophils
D. epithelial cells

A

D

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13
Q

All of the following are selective media that will inhibit the growth of Gram-positive bacteria, EXCEPT…
A. Mueller-Hinton agar
B. Mac Conkey agar
C. EMB Agar
D. Thayer-Martin agar

A

A

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14
Q

Which of the following growth patterns in a semisolid medium is consistent with a facultative anaerobe?

A
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15
Q

Inoculation Method:
Quantitative streak
Spread Plate
Pour Plate
Dilution Streak

A
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16
Q

Most bacterial cultures must be incubated at what temperature range?
A. 25 – 30 C
B. -20 - -70 C
C. 35 - 37 C
D. 37 – 40 C

A

C

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17
Q

A wound exudate sample was inoculated onto Blood agar, MacConkey agar, Chocolate agar, and Thioglycolate broth then incubated without CO . After 24 hours of incubation, no colonies were seen on all agar plates, but turbidity was observed at the bottom of the Thioglycolate tube. Which of the following is the best explanation for the observed growth pattern?
A. the organism is an obligate anaerobe
B. the organism is fastidious
C. the organism is capnophilic
D. the organism is a facultative anaerobe

A

A

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18
Q

Genetic recombination in bacteria requires at least two living bacterial cells.
A. True
B. False

A

B

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19
Q

When a Kirby-Bauer test demonstrates bacterial swarming within zones of inhibition, which of the following must be done?
A. ignore swarming and interpret the test based on the size of the inhibition zone
B. report the organism as resistant to the antibiotic
C. test the purity of the inoculum and repeat the susceptibility test
D. report the MIC as the lowest concentration with at least 80% inhibition

A

A

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20
Q

When used as a disinfectant for the microbiology laboratory, household bleach is best used as a…
A. 100% solution
B. 10-20% solution
C. 2% solution
D. 70% solution

A

B

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21
Q

A direct microscopic exam of a sputum smear shows numerous bacteria, abundant mucus, an average of 15 neutrophils per low power field, and 28 epithelial cells per low power field. Using the Barlett’s system for assessing sputum adequacy, which of the following is true?
A. the sputum sample is heavily contaminated and must be rejected
B. the specimen has minimal contamination and is adequate for culture and susceptibility testing
C. the specimen does not show evidence of active inflammation
D. the specimen is not sputum but saliva/spit

A

A

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22
Q

Transformation allows the transfer of chromosomal DNA but nit plasmid DNA
A. True
B. False

A

B

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23
Q

The following are selective media, EXCEPT…
A. Selenite F broth
B. Thioglycolate broth
C. Mannitol Salt Agar
D. Lowenstein-Jensen medium

A

B

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24
Q

Which of the following media combination is BEST for isolating and identifying non-fastidious Gram-negative bacilli and Gram-positive cocci.
A. Brain Heart Infusion agar and Blood agar
B. MacConkey agar and Sel-F broth
C. EMB agar and Blood agar 
D. Chocolate agar and PEA agar

A

C

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25
Q

Which of the following is an ideal culture medium for providing aerobic, microaerophilic, and anaerobic conditions?
A. Blood agar
B. Chocolate agar
C. Mueller-Hinton agar
D. Selenite F broth
E. Thioglycolate broth

A

E

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26
Q

Which of the following susceptibility testing methods is most appropriate when determining the susceptibility of multiple isolates/organisms against one antibiotic?
A. disk diffusion
B. agar dilution
C. E-test
D. time-kill assay

A

B

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27
Q

Sterilization using heat is applicable for the following, EXCEPT…
A. Glassware
B. Surgical equipment
C. Vaccines
D. Agar culture media

A

C

28
Q

Which of the following is a possible reason why a Gram-positive organism will appear Gram-negative under the microscope?
A. expired counterstain
B. expired mordant
C. under decolorization
D. all of the choices

A

B

29
Q

Which of the following may cause an isolate to appear susceptible when it is resistant to an antibiotic?
A. the inoculum used is lighter than the standard
B. expired antibiotic disks/reagents
C. both A and B
D. none of the choices

A

A

30
Q

Which of the following types of culture media is expected to provide more consistent and reliable results?
A. synthetic
B. non-synthetic

A

A

31
Q

Which susceptibility test method is based on broth dilution method but uses a dye as an indicator of bacterial growth?
A. E-test
B. Alamar method
C. Kirby-Bauer
D. β-lactamase test

A

B

32
Q

Which inoculation technique can facilitate both surface and subsurface growth in agar media?
A. spread plate method
B. pour plate method
C. streak plate method

A

B

33
Q

The following methods determine the MIC, except…
A. disk diffusion method
B. broth dilution method
C. Epsilomer test
D. spiral gradient endpoint system

A

A

34
Q

Which of the following is appropriate when examining a sample for spirochetes?
A. Gram staining
B. Acid-fast staining
C. Darkfield microscopy
D. Hanging-drop slide

A

C

35
Q

Gram-stain: pink
Morphology: rod

A. G+ cocci
B. G- cocci
C. G- bacilli
D. G+ bacilli

A

C

36
Q

How soon must a bacterial suspension for susceptibility testing be used after inoculum standardization?
A. within 2 hours
B. within 2 minutes
C. within 15 minutes
D. within 1 hour

A

C

37
Q

The following are differential media, EXCEPT…
A. Chromagar
B. Blood Agar
C. Hektoen Enteric agar
D. Brain Heart Infusion agar

A

D

38
Q

Antibiotic combinations are considered synergistic when…
A. the MIC of the combination is at least 3 dilutions lower
B. there is a three-fold increase in effectivity
C. the FICI is greater than 0.5
D. all of the choices

A

A

39
Q

The following are microscopy techniques that allow the visualization of live motile bacteria, EXCEPT…
A. hanging-drop method
B. darkfield microscopy
C. Gram-staining
D. saline mount

A

C

40
Q

A 5ml sample of thick purulent discharge was submitted to the laboratory for a gram stained smear. Which of the following is the appropriate smear preparation method?
A. centrifuged smear
B. layered smear
C. single drop smear
D. touch smear

A

C

41
Q

Detection methods that depend on bacterial cultures or isolation techniques cannot detect and identify dead bacteria
A. true
B. false

A

A

42
Q

The following are tasks performed on day 3 of a routine culture and susceptibility test, EXCEPT…
A. read biochemical test results
B. read susceptibility test results
C. generate and relay report
D. describe and analyze growth patterns

A

D

43
Q

Capnophilic bacteria require ____ CO2 for optimal growth.
A. 20 – 30%
B. 10 – 20%
C. 5 – 10%
D. 5 – 6%

A

C

44
Q

The following are chemical agents used for gas sterilization, EXCEPT…
A. quaternary ammonium compounds
B. ethylene oxide
C. hydrogen peroxide
D. periacetic acid
E. none of the choices

A

A

45
Q

The D-zone test is performed when initial susceptibility test results reveal…
A. resistance to clindamycin and susceptibility to erythromycin
B. susceptibility to clindamycin and resistance to erythromycin
C. resistance to erythromycin and susceptibility to gentamycin
D. susceptibility to both erythromycin and gentamycin
E. resistance to both gentamycin and clindamycin

A

B

46
Q

Catheters and endotracheal tubes come in contact with the patient’s mucous membranes. It is therefore classified as a _____ and require ____.
A. non-critical material, intermediate level disinfection
B. semi-critical material, sterilization
C. critical material, high-level disinfection
D. semi-critical material, high-level disinfection
E. critical material, sterilization

A

D

47
Q

Which of the following is best used when large numbers of contaminating bacteria are expected from a clinical sample?
A. selective media
B. differential media
C. enriched media
D. non-selective media

A

A

48
Q

An organism that grows on Chocolate agar but not on PEA is potentially…
A. a Gram-negative organism
B. a fastidious Gram-positive organism
C. either A or B
D. neither A nor B

A

C

49
Q

The following methods are used for testing antibiotic synergism, EXCEPT…
A. disk diffusion
B. broth dilution
C. agar dilution
D. none of the choices

A

C

50
Q

What must be done when trailing growth is observed in broth dilution testing?
A. report MBC as 99.9% inhibition
B. re-incubate for another 24 hours
C. interpret MIC based on 80% inhibition
D. repeat the test

A

C

51
Q

Which of the following is a method of sterilization where waste is broken down by heat and converted into fuel and other reusable materials?
A. incineration
B. pyrolysis
C. autoclaving

A

B

52
Q

Frameshift mutations are more detrimental to the cell compared to point mutations.
A. true
B. false

A

A

53
Q

Which of the following best describes a situation where antibiotic therapy fails due to an exogenous source of folate?
A. innate resistance
B. environmentally mediated resistance
C. acquired resistance
D. microorganism mediated resistance

A

B

54
Q

Which type of culture medium is used for isolating obligate intracellular parasites?
A. enriched medium
B. synthetic medium
C. broth media
D. cell culture
E. differential media

A

D

55
Q

Which of the following stains will provide the highest sensitivity when attempting to determine whether bacteria are present in a CSF sample?
A. methylene blue stain
B. darkfield microscopy
C. acridine orange stain
D. acid-fast stain
E. Gram-stain

A

C

56
Q

Arrange the following according to the sequence the procedures are performed:
1. Specimen Collection
2. Inoculum preparation and susceptibility testing
3. Reporting of results
4. Direct microscopy
5. Selection and inoculation of primary culture media

A

1, 4, 5, 2, 3

57
Q

The following are specimen collection techniques that are performed to reduce contamination with unwanted organisms, EXCEPT…
A. gargling or rinsing the mouth with water
B. use of sterile containers
C. first morning expectoration
D. skin disinfection prior to blood collection
E. midstream urine collection

A

C

58
Q

Arrange the following in increasing order according to the difficulty of killing (from least resistant to most resistant to disinfection).
1. Enveloped Viruses
2. Naked Viruses
3. Bacterial Spores
4. Mycobacteria
5. Vegetative bacteria

A

1, 5, 2, 4, 3

59
Q

Which of the following methods is appropriate when screening patients for pulmonary tuberculosis?
A. Gram staining
B. Acid-fast staining
C. Darkfield microscopy
D. Hanging-drop slide

A

B

60
Q

Which of the following is a possible reason why a Gram-negative organism will appear Gram-positive
A. expired mordant
B. expired primary stain
C. expired decolorizer
D. expired counterstain

A

C

61
Q

The recommended concentration of glutaraldehyde for sterilizing materials contaminated with tissue and/or biologic fluids is…
A. 95%
B. 2%
C. 70%
D. 10 – 20 %

A

B

62
Q

Only obligate anaerobes can be grown in anaerobic conditions.
A. True
B. False

A

B

63
Q

When determining the colony count from an agar plate that was inoculated using a 1 µL loop, the number of colonies must be multiplied by a factor of…
A. 10
B. 100
C. 1,000
D. 10,000

A

C

64
Q

Which of the following is NOT TRUE of a bacterial cell that becomes antibiotic resistant because of transformation?
A. the resistance mechanism is classified as intrinsic resistance
B. the resistance mechanism is microorganism mediated
C. the bacterial cell can transfer the genes to its progeny
D. none of the choices

A

A

65
Q

Which of the following is a medium that allows differentiation of bacteria based on H2S production?
A. MacConkey Agar
B. Eosin Methylene Blue Agar
C. Mannitol Salt Agar
D. Xylose Lysine Desoxycholate Agar

A

D

66
Q

Which of the following is true about the minimum bactericidal concentration (MBC) test?
A. It determines the rate of killing of bacteria by an antimicrobial
B. measures the lowest concentration of an antibiotic that inhibits bacterial growth
C. performed to determine ideal antibiotic therapy for immunocompromised patients
D. measures the amount of antimicrobial agent in a patient’s serum

A

C

67
Q

Which of the following must be done when an inoculum is heavier than the turbidity standard?
A. inoculate the MH agar plate
B. add more colonies
C. dilute the inoculum
D. incubate the inoculum

A

C

Clinical Bacteriology (7 decks)

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