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Micro unit 1-5 Practice questions

Terms in this set (70)

Bacteria belong to the kingdom:
a. Animalae
b. Plantae
c. Protista
d. Procaryotae
D. Procaryotae
According to binomial nomenclature, which of the following statements is correct: a. Genus names are capitalized b. Species names are not capitalized
c. Genus names are usually nouns
d. Species names are usually adjectives
e. all of the above
E. All of the above
Which of the following statements apply to Bergey's classification criteria:
a. Staining reactions
b. Shape differences c. Growth requirements
d. Biochemical and metabolic differences
e. all of the above
E. All of the above
The basic shapes of bacteria are:
a. Small, medium and large
b. Cocci and rods
c. Cocci, bacilli and spirals
d. Oval and rectangular
C. Cocci, bacilli and spirals
All of the following specimens would be expected to contain commensal flora EXCEPT:
a. Throat
b. Spinal fluid
c. Gastrointestinal tract
d. Skin
B. Spinal fluid
The ability of an organism to cause disease in a host may be related to the ability of the organism to produce:
a. Toxins
b. Extracellular enzymes
c. Capsules
d. All of the above
D. All of the above
When comparing exotoxins to endotoxins, which of the following statements is true of an exotoxin: (there are 2 answers)
a. Releases toxin only when cell is destroyed
b. Lethal dose is small
c. Mostly found in gram negative organisms
d. Some of the most powerful toxins known to man
B. Lethal does is small
D. Some of the most powerful toxins known to man
Which of the following statements applies to an endotoxin:
a. May cause septic shock
b. Found in the cell wall of all gram-positive organisms
c. Lethal dose is small
d. Does not require lysis of cell wall
A. May cause septic shock
All microorganisms are capable of producing:
a. Spores (only the GPRs Clostridium & Bacillus species) b. Capsules
c. Flagella
d. None of the above
D. None of the above
The body's natural host defense mechanisms include:
a. Skin
b. Mucous membranes
c. Phagocytosis
d. Inflammatory response
e. All of the above
E. All of the above
The most common cause of nosocomial infections is:
a. Visitors
b. Plants & flowers
c. Improper hand washing
d. Sneezing
C. Improper hand washing
The most important purpose of an infection control program is to:
a. Detect nosocomial infections b. Control nosocomial infections
c. Prevent nosocomial infections
d. All of the above
D. All of the above
The ability of an organism to cause disease in a host is referred to as:
a. Virulence
b. Pathogenicity
c. Toxigenicity
d. Opportunism
B. Pathogenicity
The most common source of error when performing Gram stains is:
a. Overdecolorizing
b. Smear too thin
c. Underdecolorizing
d. Use of an old culture
A. Overdecolorizing
Smears prepared from patient specimens are referred to as:
a. Culture smears
b. Patient smears
c. Direct smears
C. Direct smears
Approximately how many fields should be examined before you quantitate cells and bacteria on a direct smear?
a. 2 - 4
b. 5 - 10
c. 10 - 20
C. 10-20
Large cells 25 microns in diameter with a centrally located nucleus are most likely: a. Lymphocytes
b. Neutrophils
c. Epithelial cells
d. Macrophages
C. Epithelial cells
Information from a Gram stained direct patient smear can be:
a. Correlated with information from culture plates
b. Used to aid in a rapid diagnosis
c. Used to determine the quality of a specimen
d. All of the above
D. All of the above
Gram negative organisms may stain Gram positive due to:
a. Overdecolorizing
b. Underdecolorizing
c. Use of a young culture
d. All of the above
B. Underdecolorizing
Oval, budding GP structures of approximately 3 microns are most likely:
a. Gram positive cocci
b. Gram positive coccobacilli
c. Yeast
d. Gram positive diplococci
C. Yeast
Smears prepared from growing cultures are referred to as:
a. Patient smears
b. Culture smears
c. Direct smears
d. Plate smears
B. Culture smears
Cultures for Gram stains, biochemical testing and susceptibility testing should be no older than
a.4 hours
b.8 hours
c. 24 hours
d.48 hours
C. 24 hours
White blood cells in a Gram stained patient smear that has been adequately decolorized should appear:
a.Pink-Red
b.Purple
A. Pink-red
The cell walls of gram-negative organisms contain a high concentration of:
a. Carbohydrates
b. Lipids
c. Peptidoglycan
d. All of the above
B. Lipids
Which of the following nonbacterial elements is an indication of inflammation and/or infection:
a. Red blood cells
b. Epithelial cells
c. White blood cells
d. Yeast
C. White blood cells
Which of the following is an invasive form of fungi:
a. Cocci
b. Rods
c. Hyphae
d. Yeast
C. Hyphae
Gram positive cells are purple after decolorization because:
a. The alcohol reacts with the safranin to stain the cells that color
b. They retain the safranin through decolorization
c. The iodine prevents the cells from losing the crystal violet through decolorization
d. They retain the crystal violet through decolorization
D. They retain the crystal violet through decolorization
What type of blood agar is recommended for use in clinical microbiology?
a. human
b. goat
c. rabbit
d. sheep
D. Sheep
What is/are the advantage(s) of sheep blood agar?
a. it is more enriched
b. consistent colony characteristics
c. it has a longer shelf life
d. all of the above
B. Consistent colony characteristics
What percent of blood is actually in sheep blood agar? a. 1%
b. 5%
c. 10%
d. 25%
B. 5%
Which of the following is considered the MOST enriched routine plating media?
a. MacConkey
b. Columbia CNA
c. Sheep blood agar
d. Chocolate agar
D. Chocolate agar
Which of the following media is considered a differential as well as selective media?
a. chocolate agar
b. MacConkey agar
c. Phenylethyl alcohol agar
d. Sheep blood agar
B. MacConkey agar
Pink colonies on MacConkey indicate that:
a. lactose has been fermented b. the organism is a GPC
c. phenol red has turned pink
d. all of the above
A. Lactose has been fermented
The majority of human pathogens are classified as:
a. psychrophils
b. mesophils
c. thermophils
d. none of the above
B. Mesophils
Since pH is temperature dependent, the pH of media should be determined:
a. before autoclaving media
b. immediately after autoclaving
c. after media has cooled to room temperature
d. it doesn't matter!
A. Before autoclaving media
Chocolate agar contains:
a. X&V factors
b. Yeast & hemin
c. Hemin & NAD
d. All of the above
D. All of the above
All of the following statements describe the logarithmic phase in the bacterial growth
cycle EXCEPT:
a. rate of growth is maximal and characteristic for each organism
b. bacterial cells are most resistant during this phase
c. bacterial cells are most vulnerable to antimicrobial agents
d. bacterial population is doubling every 20 minutes
B. Bacterial cells are most resistant during this phase
Used needles from blood collection should be:
a. recapped and placed in a biohazard bag
b. placed in a biohazard bag and autoclaved
c. placed in a biohazard bag with bleach
d. placed in a puncture-proof container
D. Placed in a puncture-proof container
Nonmetallic surfaces contaminated with blood should be disinfected with:
a. a phenol solution
b. 70% alcohol
c. 10% bleach
d. green soap
C. 10% bleach
Which of the following techniques would be suitable for the sterilization of
plastics:
a. filtration
b. ethylene oxide (gas sterilizer)
c. steam autoclave
d. lyophilization
B. Ethylene oxide (gas sterilizer)
Which of the following techniques would be suitable for the sterilization of
vaccines or complex carbohydrate solutions:
a. filtration
b. ethylene oxide
c. steam autoclave
d. lyophilization
A. Filtration
Which of the following organisms is utilized for the quality control of the
steam autoclave:
a. Escherichia coli
b. Staphylococcus aureus
c. Geobacillus stearothermophilus
d. Clostridium perfringens
C. Geobacillus
At what concentration is alcohol most effective as a disinfectant:
a. 100%
b. 95%
c. 70%
d. 5 - 10%
C. 70%
What is the most resistant form of an organism:
a. capsule
b. spore
c. rods
d. cocci
B. Spore
The steam autoclave method of sterilization:
a. uses 100C for 15 minutes
b. utilizes dry heat for 20 minutes
c. uses 121C for 15 minutes
d. uses 20 lbs of pressure for 35 minutes
C. Uses 121C for 15 minutes
Which of the following best describes the colony morphology of Staph aureus on SBA:
a. small, pinpoint, nonhemolytic
b. medium, creamy, usually beta hemolytic
c. flat, clear, alpha hemolytic
d. pinpoint, white, usually beta hemolytic
b. medium, creamy, usually beta hemolytic
All of the following are true statements about Staphylococcus infections EXCEPT:
a. Staph. saprophyticus is associated with UTIs in young females
b. Coagulase-negative staphs are often associated with indwelling prosthetic devices
and catheters
c. Airborne transmission is the most common
d. Toxic shock syndrome and scalded skin syndrome are caused by toxin producing
strains of Staph. aureus
c. Airborne transmission is the most common
The current antimicrobial agent for the treatment of hospital-acquired MRSA infections
is:
a. vancomycin
b. naficillin + gentamicin
c. penicillin
d. methicillin
a. vancomycin
A staph produced a fibrin clot in the tube coagulase test, but not in the slide test. This
organism:
a. produced only free coagulase and is most likely Staph. aureus
b. produced only bound coagulase and is most likely Staph. aureus
c. is most likely Staph. epidermidis because of the negative slide test
d. is most likely Staph. epidermidis since the slide test is unreliable
a. produced only free coagulase and is most likely Staph. aureus
Which statement is incorrect for Staph. epidermidis:
a. coagulase negative
b. fails to grow on mannitol salt agar
c. Dnase negative
d. Susceptible to novobiocin
b. fails to grow on mannitol salt agar
Growth surrounded by yellow halos on mannitol salt agar indicates:
a. the organism cannot ferment mannitol
b. the organism cannot tolerate high salt concentrations
c. the organism can sustain high salt concentrations and ferment mannitol
d. none of the above
c. the organism can sustain high salt concentrations and ferment mannitol
Which of the following infections can be attributed to Staph. aureus:
a. skin and wound
b. toxic shock syndrome
c. osteomyelitis & food poisoning
d. All of the above
d. All of the above
Staph. saprophyticus can be distinguished from other coagulase-negative staph by:
a. novobiocin resistance
b. neomycin resistance
c. novobiocin susceptibility
d. tetracycline resistance
a. novobiocin resistance
The enterotoxin of Staph. aureus causes symptoms of:
a. meningitis
b. respiratory distress
c. food poisoning
d. sinusitis
c. food poisoning
The coagulase test is used to distinguish Staph aureus from:
a. strep
b. MRSA
c. CoNS
d. Enterococcus
c. CoNS
The Staphylococci may be distinguished from Streptococci by the presence of:
a. catalase
b. coagulase
c. beta-hemolysis
d. alpha-hemolysis
a. catalase
The structure of the gram positive cell wall allows gram positive organisms to:
a. retain safranin complexes
b. retain crystal violet-iodine complex
c. accelerate decolorization
d. accept counterstain
b. retain crystal violet-iodine complex
The Micrococcaceae divide in multiple planes, most often resulting in:
a. single-cell arrangement
b. chains of cells
c. pairs and clusters
d. lancet shaped cells
c. pairs and clusters
Of the following bacteria, the most frequent cause of prosthetic heart valve infections
occurring within 2-3 months after surgery is:
a. Streptococcus pneumoniae
b. Staphylococcus aureus
c. Streptococcus pyogenes
d. Staphylococcus epidermidis
d. Staphylococcus epidermidis
A urine gram stain shows GPC in clusters. To speciate this organism from culture, the
technician should perform:
a. catalase
b. oxidase
c. beta-lactamase
d. novobiocin inhibition
d. novobiocin inhibition
Gram stain examination from a blood culture shows dark blue, spherical organisms in
clusters. Growth on sheep blood agar shows small, round, pale yellow colonies. Further
tests should include:
a. catalase and coagulase production
b. bacitracin susceptibility and serotyping
c. oxidase and DNA
d. VP and MR reactions
a. catalase and coagulase production
A beta-hemolytic, catalase positive, GPC is coagulase-negative by the slide coagulase
test. Which of the following is the most appropriate action in identification of this
organism:
a report a coagulase-negative Staph
b. report a coagulase-negative Staph aureus
c. reconfirm the hemolytic reactions on fresh 24 hr
culture
d. do a tube coagulase test to confirm the slide test
d. do a tube coagulase test to confirm the slide test
The enterotoxin produced by certain strains of hemolytic, coagulase positive Staph
aureus:
a. is destroyed by boiling for 15-30 minutes
b. is identical to dermonecrotic toxin
c. causes one type of bacterial food poisoning
d. causes TSS
c. causes one type of bacterial food poisoning
What Gram stain morphology does Micrococcus species have:
a. GPC in chains
b. GPC in pairs
c. GPC in clusters
d. GPC in tetrads
d. GPC in tetrads
A blood culture from an IV drug abuser grows out GPC with the following characteristics:
catalase positive, coagulase-negative, multiple drug resistant. What is the most likely
organism:
a. Staphylococcus epidermidis
b. Staphylococcus aureus
c. Micrococcus species
d. Staphylococcus saprophyticus
a. Staphylococcus epidermidis
A young woman is seen for symptoms of a urinary tract infection. Although her urine
culture only grew 20,000 organisms/ml, it is a pure culture. It is catalase positive,
coagulase-negative and novobiocin resistant. Name that organism!
a. coagulase negative Staph
b. Staph aureus
c. Staph epidermidis
d. Staph saprophyticus
d. Staph saprophyticus
Staphylococcus food poisoning is characterized by:
a. rapid onset within 2-6 hours of ingestion of
enterotoxin
b. colonization of the GI tract by bacterium
c. 2 days to 2-week incubation period
d. diarrhea, but no vomiting
a. rapid onset within 2-6 hours of ingestion of
enterotoxin
Staphylococcus epidermidis is associated with all of the following
except
a. wound infections
b. bacteremia
c. nosocomial UTls
d. Toxic Shock Syndrome
d. Toxic Shock Syndrome
A positive blood culture shows GPC in tetrads. The following day yellow pigmented
colonies are observed on SBA. The catalase and modified oxidase reaction are
positive.
What is the most likely agent:
a. Staph epidermidis
b. Stomatococcus
c. Micrococcus
d. Staph saprophyticus
c. Micrococcus
A wound culture grew a GPC that was beta hemolytic, catalase positive and
coagulase positive. Name the organism!
a. Staphylococcus epidermidis
b. Staphylococcus aureus
c. Micrococcus species
d. Staphylococcus saprophyticus
b. Staphylococcus aureus
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