Deck 15: Introduction to Microbiology

Question 1

All of the following are structures found in prokaryotic organisms except:

A) mitochondria.
B) capsules.
C) ribosomes.
D) cell wall.

Answer 1

mitochondria.

Question 2

Which of the following is the "cold" method for staining acid-fast bacteria?

A) Ziehl-Neelsen
B) Kinyoun
C) Fluorochrome
D) All of the above

Answer 2

Kinyoun

Question 3

Sending appropriately collected specimens to the laboratory before antibiotic therapy is initiated is important because:

A) pathogenic bacteria could be hard to recover because of the effects of the antibiotic.
B) collection of specimens from around the wound area can result in contamination of the culture.
C) collection of a sputum specimen contaminated with saliva could yield a culture result that reflects normal mouth flora.
D) All of the above are correct.

Answer 3

All of the above are correct.

Question 4

The prefix strepto- refers to bacteria in which of the following groupings?

A) Clusters
B) Pairs
C) Chains
D) Singular

Question 5

The technique of killing or destroying all microorganisms including bacterial spores (endospores)is called:

A) antisepsis.
B) sterilization.
C) physical disinfection.
D) chemical disinfection.

Question 6

What is the biosafety level of most clinical microbiology laboratories?

A) Biosafety Level 1
B) Biosafety Level 2
C) Biosafety Level 3
D) Biosafety Level 4

Question 7

Mycology is the study of:

A) viruses.
B) parasites.
C) yeasts and molds.
D) bacteria.

Question 8

Which of the following specimen types for culture can be collected in a clean,nonsterile container?

A) Urine
B) Stool
C) Cerebrospinal fluid
D) Blood

Question 9

Which of the following bacteria are typically stained using the acid-fast technique?

A) Mycobacteria
B) Staphylococci
C) Streptococci
D) Escherichia coli

Question 10

A growth of bacteria that began as one parent bacterium and divided multiple times to become a visible aggregate is called a:

A) culture.
B) pure culture.
C) slant culture.
D) colony.

Question 11

Which of the following systematic designations is correct?

A)
B)
C)
D)

Question 12

What is the name of the type of infection that is acquired in a hospital?

A) Opportunistic infection
B) Normal flora
C) Community acquired infection
D) Nosocomial infection

Question 13

Which of the following is a differential stain used routinely in microbiology laboratories?

A) Methylene blue
B) Flagella stain
C) Gram stain
D) Capsule stain

Question 14

Routine microbiology laboratories have incubators that are set at all of the following temperatures except:

A) 30° C.
B) 35° C.
C) 42° C.
D) 50° C.

Question 15

What is the color of gram-negative bacterial cells after the decolorization step?

A) Purple/blue
B) Red/pink
C) Iodine yellow
D) Colorless

Question 16

Which of the following is a false statement when considering proper disinfection processes?

A) The disinfectant should be dried immediately for best results.
B) Phenol and diluted bleach are two effective disinfectants.
C) The work area should be disinfected prior to use and again when work is completed.
D) Disinfection is an ongoing process.

Question 17

Which of the following is a sterilization procedure that uses moist heat and how is this method effective in killing bacterial spores?

A) Filtration; filters all microbes larger than the filter pore size
B) Boiling; kills all microorganisms and spores at 100° C (boiling)
C) Hot-air chamber; kills all microorganisms and bacterial spores at 171° C for at least 1 hour
D) Autoclaving; kills all microorganisms and bacterial spores at 121° C for 15 minutes at 15 lb above atmospheric pressure

Question 18

Which of the following methods is appropriate to collect blood for culture?

A) Cleaning the venipuncture site with 70% alcohol
B) Cleaning the venipuncture site with 70% alcohol, followed by povidone-iodine, at the intended venipuncture site
C) Cleaning the venipuncture site with 70% alcohol, followed by povidone-iodine, moving in a circular motion beginning at the periphery of the area to be cleaned inward toward the venipuncture site
D) All of the above

Question 19

Why do gram-positive bacterial cells retain the crystal violet-iodine complex when the decolorizer is added?

A) Gram-positive cells have an outer membrane that traps the complex.
B) Gram-positive bacterial cells have a thinner peptidoglycan layer with teichoic acid cross-linkages.
C) Gram-positive bacterial cells have a thicker peptidoglycan layer with teichoic acid cross-linkages.
D) Gram-positive bacterial cells have a thick capsule layer that traps the complex.

Question 20

Which of the following specimens can be refrigerated?

A) Urine for routine culture
B) Cerebrospinal fluid
C) Genital culture
D) Culture for meningitis

Question 21

Media that have dyes,antibiotics,or other chemical compounds added to inhibit certain bacteria while allowing others to grow is called ____ media.

A) enrichment
B) supportive
C) selective
D) differential

Question 22

A positive leukocyte esterase and nitrite test (urine rapid-screening test strips)indicates:

A) most likely the patient has a UTI.
B) the patient definitely does not have a UTI.
C) a new specimen should be collected because these tests indicate contamination.
D) the test strips are not reacting properly, and the quality control should be rechecked.

Question 23

The technologist uses TSI and LIA agars to rule out stool pathogens,Salmonella and Shigella spp.The reactions observed are TSI: K/A H2S+ and LIA: K/K.What should the technologist do next?

A) Report Salmonella spp. recovered
B) Report Shigella spp. recovered
C) Do further biochemical and serological testing to confirm Salmonella spp.
D) Repeat all testing

Question 24

Chocolate agar contains all of the following except:

A) antibiotics.
B) X factor.
C) V factor.
D) lysed blood.

Question 25

Which of the following is an organism that can grow in the presence or absence of oxygen?

A) Aerobe
B) Anaerobe
C) Facultative anaerobe
D) Microaerophile

Question 26

A clean-catch midstream urine specimen is sent to the laboratory for culture.The results of the culture yield three organisms present,with no predominating organism.What type of workup should the technologist do?

A) Complete workup of all organisms present
B) No workup because of possible contamination
C) Workup one of the organisms
D) Workup two of the organisms

Question 27

If a microbiologist wants to add a selective and enriched medium for the recovery of Neisseria gonorrhoeae from genital specimens,which of the following would be appropriate?

A) Chocolate agar (CHOC)
B) Sheep blood agar (SBA or BA)
C) Modified Thayer-Martin agar (MTM)
D) Phenylethyl alcohol agar (PEA)

Question 28

The microbiologist uses TSI and LIA agars to rule out stool pathogens,Salmonella and Shigella spp.The reactions observed are TSI: K/A,H2S+ and LIA: R/A.What should the technologist do next?

A) Report Salmonella spp. recovered
B) Report Shigella spp. recovered
C) Report normal stool flora
D) Repeat all testing

Question 29

Which type of microscope is used to observe acid-fast bacteria when they are stained with auramine and rhodamine?

A) Brightfield
B) Electron
C) Fluorescent
D) All of the above

Question 30

Which of the following media contain sodium thiosulfate and ferric ammonium citrate for the detection of hydrogen sulfide production?

A) Triple sugar iron agar (TSI)
B) Lysine iron agar (LIA)
C) Xylose-lysine-desoxycholate agar (XLD)
D) All of the above

Question 31

Which of the following is a rapid method to screen sputum specimens for the yeast Cryptococcus neoformans?

A) Coagulase
B) Urease
C) Indole
D) Oxidase

Question 32

Which of the following is the appearance of a positive catalase test?

A) Fibrin clot
B) Bubbles of oxygen
C) Visible clumping
D) Blue-green color

Question 33

A microbiologist observes colonies on Hektoen enteric agar (HE)that appear green.Which of the following organisms should the microbiologist suspect?

A) Salmonella spp.
B) Escherichia coli
C) Proteus spp.
D) Shigella spp.

Question 34

Where do strict aerobes grow in thioglycolate broth?

A) At the top
B) In the middle
C) At the bottom
D) Throughout the broth

Question 35

Growth of several colonies originating from a single colony,and thus a single cell,is known as a:

A) subculture.
B) primary culture.
C) mixed culture.
D) pure culture.

Question 36

Which of the following is a selective and differential medium for the recovery of gram-positive organisms?

A) Columbia colistin-nalidixic acid agar with blood (CNA)
B) Eosin-methylene blue agar (EMB)
C) MacConkey agar (MAC)
D) Xylose-lysine desoxycholate agar (XLD)

Question 37

Which of the following tests identifies Staphylococcus aureus?

A) PYR and catalase
B) Catalase and coagulase
C) Bile solubility and optochin
D) Indole and oxidase

Question 38

The Gram stain is used to differentiate bacteria that have similar morphologic features.The Gram stain method uses different reagents,including:

A) Gram iodine.
B) decolorization.
C) a counterstain.
D) all of the above.

Question 39

Which of the following refers to colony morphology?

A) Cocci in chains
B) Shiny, wet, or mucoid
C) Yellow, dry, rough
D) Both b and c

Question 40

Media that contain factors such as lactose with an indicator present to give distinctive,recognizable characteristics is called ____ media.

A) enrichment
B) supportive
C) selective
D) differential

Question 41

Which of the following is the least desirable specimen for fungal cultures?

A) Hair
B) Skin
C) Sterile body fluids
D) Swabs

Question 42

Which of the following is an obligate intracellular pathogen that is a prevalent sexually transmitted disease?

A) Gardnerella vaginalis
B) Neisseria gonorrhoeae
C) Chlamydia trachomatis
D) Trichomonas vaginalis

Question 43

A microbiologist is preparing a Mueller-Hinton agar for disk diffusion testing and has inoculated the plate with the appropriate standardized inoculum.The microbiologist is interrupted by a phone call from a physician that takes 20 minutes to track the requested information.How should the technologist proceed with the disk diffusion testing?

A) Continue as planned and place the disks on the agar plate.
B) Continue as planned, but add quality control testing to ensure proper results.
C) Discard the plate and, with the same inoculum, swab a new Mueller-Hinton agar.
D) Discard the plate and the inoculum and start anew.

Question 44

Automated methods of culturing blood have replaced traditional methods in most laboratories because of:

A) more rapid detection time for many pathogens.
B) monitoring of growth without visual inspection or subculture of the bottles.
C) the ability to use the report in conjunction with a computerized laboratory management information system.
D) all of the above.

Question 45

Which of the following describes alpha hemolysis on sheep blood agar?

A) Complete clearing around the colonies of the red blood cells in the medium
B) Partial hemolysis of the red blood cells in the medium appearing as a green discoloration of the medium
C) Partial hemolysis of the red blood cells in the medium appearing as a slight clearing around the colonies
D) No hemolysis of the red blood cells in the medium; therefore no change in the color of the medium

Question 46

The lowest concentration of an antimicrobial agent that will visibly inhibit the growth of the organism being tested is called:

A) bacteriostatic.
B) bactericidal.
C) minimal inhibitory concentration (MIC).
D) minimum bactericidal concentration (MBC).

Question 47

Which of the following organisms can be routinely detected by culture and nucleic acid testing?

A) Gardnerella vaginalis
B) Neisseria gonorrhoeae
C) Chlamydia trachomatis
D) Both b and c

Question 48

A fungal infection that affects the deeper layers of the skin,including muscle and connective tissue,is called ____ mycosis.

A) superficial
B) cutaneous
C) subcutaneous
D) systemic

Question 49

Rapid screening of throat specimens (nonculture method)is done to detect which of the following pathogens?

A) Streptococcus pneumoniae
B) Escherichia coli
C) Group A b-hemolytic Streptococcus
D) Staphylococcus aureus

Question 50

Which of the following bacteremias can result from possible wound abscesses and are present for a time in the blood,followed by a period with no bacteria?

A) Intermittent bacteremia
B) Transient bacteremia
C) Septicemia
D) Continuous bacteremia

Question 51

A common gram-negative organism found in blood is:

A) Staphylococcus aureus.
B) Escherichia coli.
C) coagulase-negative staphylococci.
D) Streptococcus pneumoniae.

Question 52

Which of the following is done to identify Streptococcus pneumoniae?

A) Ethylhydrocupreine hydrochloride
B) Optochin
C) Bile solubility
D) Desoxycholate

Question 53

Which of the following is false about blood cultures?

A) Blood/medium ratio 1:2 to 1:5
B) Blood/medium ratio 1:5 to 1:10
C) Sodium polyanethol sulfonate (anticoagulant)
D) Broth medium

Question 54

All of the following are characteristics of fungi except:

A) cell wall made of peptidoglycan.
B) hyphae.
C) "fuzzy" or woolly appearance.
D) eukaryotic.

Question 55

If a urine culture was planted using a 0.001-mL loop and 75 colonies were observed,what is the colony-forming units per millimeter of urine (CFU/mL)?

A) 75 CFU/mL
B) 750 CFU/mL
C) 7500 CFU/mL
D) 75,000 CFU/mL

Question 56

Which of the following is one cause of bacterial vaginosis and is best diagnosed by the presence of microscopic "clue cells"?

A) Gardnerella vaginalis
B) Neisseria gonorrhoeae
C) Chlamydia trachomatis
D) Trichomonas vaginalis

Question 57

Which of the following tests can be used to identify group A b-hemolytic Streptococcus?

A) PYR test
B) Bacitracin disk
C) Optochin
D) Both A and B

Question 58

How do you interpret no zone of inhibition around an antibiotic disk in the disk diffusion method?

A) Susceptible
B) Resistant
C) Intermediate
D) Repeat testing; there should always be a zone of inhibition.

Question 59

A progressive syndrome with symptoms of fever,chills,low blood pressure,respiratory distress,and disseminated intravascular coagulation is called:

A) bacteremia.
B) septic shock.
C) transient bacteremia.
D) exotoxin.

Question 60

Which of the following is an agar disk diffusion method of testing for antimicrobial susceptibility?

A) Microdilution
B) Macrodilution
C) Kirby-Bauer method
D) MBC

Question 61

Interpret the following case study:
A 25-year-old woman presents to the emergency department with vaginal discomfort.The physician ordered a hanging drop (wet preparation for Trichomonas vaginalis),KOH preparation,Gram stain,culture,and Gen-Probe.The results are:
Hanging drop: no motile trichomonas seen,clue cells present
KOH preparation: no fungal elements seen
Gram stain:
Many gram-variable bacilli
Few squamous epithelia
Rare amount gram-positive bacilli
Genital culture: pending
Gen-Probe: negative for Neisseria gonorrhoeae and negative for Chlamydia trachomatis

Question 62

The cellophane tape method is used to detect which of the following?

A) Plasmodium spp.
B) Trichomonas vaginalis
C) Enterobius vermicularis
D) Pneumocystis jiroveci

Question 63

What is the recommended protocol for collection of stool specimens for ova and parasite (O&P)detection?

A) Three stool samples 1 or 2 days apart, all within a 10-day period
B) Two stool samples 1 or 2 days apart, all within a 5-day period
C) Three stool samples 1 or 2 days apart, all within a 5-day period
D) Two stool samples 1 or 2 days apart, all within a 10-day period

Question 64

Which of the following are the nematodes?

A) Roundworms
B) Flatworms
C) Tapeworms
D) Flukes

Question 65

Motile trophozoites found microscopically in fresh urine or fresh genital secretions is diagnostic for which of the following parasites?

A) Plasmodium spp.
B) Trichomonas vaginalis
C) Enterobius vermicularis
D) Pneumocystis jiroveci

Question 66

Which of the following procedures can identify Candida albicans?

A) India ink stain
B) Germ-tube test
C) Gram stain
D) Acid-fast stain

Question 67

Which of the following is the feeding and reproductive stage of protozoa and what consistency of stool would you usually find them in?

A) Cysts; loose or watery stool
B) Cysts; formed stool
C) Trophozoites; loose or watery stool
D) Trophozoites; formed stool

Question 68

Which of the following organisms can be detected by India ink staining and appear as budding yeast surrounded by a large clear area (capsule)?

A) Nocardia spp.
B) Candida albicans
C) Cryptococcus neoformans
D) Candida spp.

Question 69

Which of the following specimens is appropriate for detection of Plasmodium spp.?

A) Stool
B) Wound
C) Blood
D) Urine

Question 70

Interpret the following Gram stain of urethral discharge from a male:
Many polymorphonuclear leukocytes (PMNs)
Few gram-negative intracellular diplococci