Bacteriology Pre-Test

The aseptic collection of blood cultures requires

that the skin be cleansed with:

70% alcohol and then 2% iodine or an iodophor

When cleansing the skin with alcohol and then

iodine for the collection of a blood culture, the

iodine (or iodophor) should remain intact on

the skin for at least:

60 sec

What is the purpose of adding 0.025% - 0.050% sodium polyanethol sulfonate (SPS) to nutrient broth media for the collection of blood cultures?

Inhibits phagocytosis and complement

Select the media of choice for recovery of Vibrio cholerae from a stool specimen:

TCBS and alkaline peptone water

According to CLSI, _____________ is the recommended skin disinfectant for blood culture, for infants two months and older, and patients with iodine sensitivity.

Zephiran chloride

Iodophor

Chlorherxidine gluconate

Benzalkonium chloride solution

Chlorherxidine gluconate

Cycloserine-cefoxitin-fructose agar (CCFA) is used for the recovery of:

Clostridium difficile

Prereduced and Vitamin K1 supplemented blood agar plates are recommended isolation media for:

Bacteroides, Peptostreptococcus and Clostridium spp.

Which procedure is appropriate for culture of genital specimens in order to recover Chlamydia spp.?

Inoculate cycloheximide treated McCoy’s cells

Plate onto blood and chocolate agar

Inoculate into thioglycolate broth

Plate onto modified Thayer-Martin agar within 24 hours

Inoculate cycloheximide treated McCoy’s cells

At which pH does the methyl red (MR) test become positive?

4.5

Which of the following reagents is added to detect the production of indole?

p-dimethylaminobenzaldehyde

Which genera of Enterobacteriacea are usually nonmotile at 36^oC?

Shigella, Klebsiella and Yersinia

A visitor to South America returns with diarrhea, and infection with Vibrio cholerae is suspected. Select the bast media for recovery and identification of this organism.

TCBS agar

What atmospheric condition is needed to recover Campylobacter spp. from specimens inoculated onto a Campy-selective agar at 35-37C and 42C?

5% O2, 10% CO2, and 85% N2

Which medium should be used to recover Bordetella pertussis from a nasopharyngeal specimen?

Bordet-Gengou agar

Slime production is associated with which Staphylococcus species?

S. epidermidis

S. saprophyticus is best differentiated from S. epidermidis by susceptibility to:

5 ug novobiocin

The bile solubility test causes lysis of:

Streptococcus pneumoniae colonies on a blood agar plate

Streptococcus pneumonia and Viridans streptococci can be differentiated by which test?

Optochin disk test

The salt tolerance test (6.5% salt broth) is used to presumptively identify:

Grp D streptococci (enterococci)

The Quellung test is used to identify which Streptococcus spp.?

S, pneumonia

Which of the following organisms is the cause of Lyme disease?

Borrelia burgdorferi

Primary atypical pneumonia is caused by:

Mycoplasma pneumoniae

Which organism typically produces “fried-egg” colonies on agar within 1-5 days of culture from a genital specimen?

Mycoplasma hominis

A direct smear from a nasopharyngeal swab stained with Loeffler’s methylene blue stain showed various letter shapes and metachromatic granules. The most likely identification is:

Corynebacterium spp.

Which of the following is the best rapid, noncultural test to perform when Gardnerella vaginalis is suspected in a patient with vaginosis?

10% KOH

A gram-positive spore-forming bacillus growing on blood agar anaerobically produces a double zone of beta-hemolysis and is positive for lecithinase. What is the presumptive identification?

Clostridium perfringens

Which spore type and location is found on C. tetani?

Round, terminal spores

Which Clostridium spp. is most often recovered from a wound infection with gas gangrene?

C. perfringens

A Gram stain smear taken from the periodontal pockets of a 30-year-old male with poor dental hygiene showed sulfur granules containing gram-positive rods (short diphtheroids and some unbranched filaments). Colonies on blood agar resembled “molar teeth” in formation. The most likely organism is:

Actinomyces israelii C.

Mycobacteria stained with Ziehl-neelsen or Kinyuon methods using a methylene blue counterstain, are seeni mcroscopically as:

Bright red rods against a blue background

Which tests are most appropriate to differentiate

between Pseudomonas aeruginosa and

Pseudomonas putida?

Mannitol, nitrate reduction, growth at 42°C

Which test group best differentiates Acinetobacter

baumannii from P. aeruginosa?

Oxidase, motility, NO3 reduction

Chinese letter appearance

Corynebacterium spp

Tumbling motility

L. monocytogenes

The test used most often to separate the

Micrococcaceae family from the Streptococcaceae

family is:

Catalase

Micrococcus and Staphylococcus species are

differentiated by which test(s)?

Fermentation of glucose (OF tube)

Which of the following enzymes contribute to the

virulence of S. aureus?

Hyaluronidase and β-lactamase

Toxic shock syndrome is attributed to

infection with:

Staphylococcus aureus

Bacitracin A disks (0.04 unit) are used for the

presumptive identification of which group of

β-hemolytic streptococci

Group A

The bile solubility test causes the lysis of:

Streptococcus pneumoniae colonies on a blood agar plate

Large gram-positive spore-forming rods growing

on blood agar as large, raised, β-hemolytic colonies

that spread and appear as frosted green-gray glass

are most likely:

Bacillus spp.

Which is the specimen of choice for proof of food

poisoning by Bacillus cereus?

Food

A suspected Bacillus anthracis culture obtained

from a wound specimen produced colonies that

had many outgrowths (Medusa-head appearance),

but were not β-hemolytic on sheep blood agar.

Which test should be performed next?

Penicillin (10-unit) susceptibility test

Which of the following organisms is the cause of

Lyme disease?

Borrelia burgdorferi

The diagnostic method most commonly used for

the identification of Lyme disease is:

Serology

Anaerobic bacteria are routinely isolated from

all of the following types of infections except:

Lung abscesses

Brain abscesses

Dental infections

Urinary tract infections

Urinary tract infections

All of the following genera are anaerobic cocci that

stain gram positive except:

Peptococcus spp.

Peptostreptococcus spp.

Streptococcus spp.

Veillonella spp.

Veillonella spp.

Which Clostridium species is most often recovered

from a wound infection with gas gangrene?

C. perfringens

Which organism, associated with tuberculosis in

cattle, causes tuberculosis in humans, especially in

regions where dairy farming is prevalent?

Mycobacterium bovis

The best specimen for recovery of the mycobacteria

from a sputum sample is:

First morning specimen