64 terms

microbiology ascp

Proper media for culture of a urethral discharge from a man include:
chocolate and modified Thayer-Martin agars
A sheep blood agar plate inoculated with 0.001 mL of urine grows 70 colonies of Staphylococcus aureus. How many colony forming units per mL of urine should be reported?
The lowest concentration of antibiotic that inhibits growth of a test organism is the what?
Minimum inhibitory concentration
Which of the following clean catch urine culture colony counts indicates the patient likely has a urinary tract infection?
10^3 CFU/mL
the steam autoclave method of sterilization:
uses 15 lbs of pressure for 15 mins
The expected colony count in a suprapubic urine from a healthy individual is:
0 CFU/mL
An aspirate of a deep wound was plated on blood agar plates and incubated aerobically and anaerobically. At 24 hours there was growth on both plates. This indicates that the organism is a:
facultative anaerobe
A penicillin-resistant Neisseria gonorrhoeae produces:
Which selective medium is used for the isolation of gram positive microorganisms?
Columbia CNA with 5% sheep blood
An enterococcus isoloted from multiple blood cultures in a patient with endocarditis should be
screened for high level aminoglycoside resistance
Three sets of blood cultures were obtained from an adult patient with fever and suspected endocarditus. The aerobic bottle of one set had growth of staphylococcus epidermidis at 5 days of incubation. This indicates that:
The organism is most likely a contaminant
In order to isolate Camoylobacter coli/jejuni the fecal specimen should be:
inoculated onto selective plating media and incubated in reduced oxygen with added CO2 at 42*C

(micraerophillic atmosphere and selective media are needed for Campylobacter)
An expectorated sputum is sent to the laboratory for culture from a patient with respiratory distress. The gram stain of the specimen shows many squamous epithelial cells (>/lpf) and rare neutrophlis. The microscope appearance of the organisms present include:

moderate gram positive cocci in chains and diplococci

moderate gram-negative diplococci

moderate palisading gram-positive bacilli

This Gram stain is most indicative of :
oropharyangeal flora
Which of the following groups of specimens would be acceptable for anaerobic culture?
pleural fluid, brain abcess.
In disc diffusion susceptibility testing, as antimicrobial agent diffuses away from the disk, the concentration of antibiotic is:
The most common cause for failure of a GasPac anaerobic jar to establlish an adequate enviroment for anaerobic incubation is:
catalyst that have become inactivated after repeated use
Which of the following specimen request is acceptable?
urine for culture of acid fast bacilli
Cerebrospinal fluid from a febrile 25 year old man with possible meningitus is rushed to the laboratory for a stat Gram stain and culture.While performing the Gram stain, the technologist accidently spills most of the specimen. The smear shows many neutrophils and no microorganisms. Since there is only enough CSF to inoculate one plate, the technologist should usa a:
chocolate agar plate
A Gram stain from a swab of a hand wound reveals:

moderate neutrophils

no squamous epithelial cells

moderate gram positive cocci in chains

moderate large gram negative bacilli

Select the appropriate media that will selectively isolate each organism.
Columbia CNA, MacConkey
An antibiotic that inhibits cell wall synthesis is:
Which one of the following organisms does not require susceptibility testing to the antimicrobial indicated when isolated from a clinically significant source.
Streptococcus pyogenes-penicillin
Which of the following antibiotics would routinely be tested and reported for isolates of Pseudomonas aruginosa?

(Gentamycin is an aminoglycoside)
Which of the folllowing must be incubated in a microaerophilic enviroment for optimal recovery of the organism?
Campylobacter jejuni
Vibrio parahemolyticus can be isolated best from feces on:
thiosulfate citrate bile salts (TCBS) agar
Which of the following media can be used to culture Campylobacter jejuni?
Skirrow medium
The best medium for culture of Bordetella pertusis is:
Regan Lowe agar
When processing throat swabs for group A Streptococcus culture, the medium of choice is:
sheep blood agar
A 21 year old patient presents with pharyngitis. A throat swab is collected and submitted for anaerobic culture. This specimen should be:
rejected as unacceptible

ananerobic bacteria do not cause pharyngitis
When using a control strain of staphylococcus aureus, the technologist notices that the zone around the oxacillin disk is too small. Which of the following is the most likely explanation?
use of outdated oxacillin disks
Which of the following organisms may be mistaken for Neissseria gonorrhoeae in Gram stained smears of uterine cervex exudates:
Moraxella osloensis
A 73 year old man diagnosed as having pneumococcal meningitis is not responding to his penicillin therapy. Which of the following test should be performed on the isolate to best determine this organisms susceptibility to penicillin?
oxacillin disk diffusion
The susceptibility results below are reported on an Enterococcus faecalis isolated from peritoneal fluid:

Ampicillin: susceptible

vancoumycin: resistant

clindamycin; susceptible

levofloxacin: resistant

linezolid: susceptible

The physican calls questioning the results. Which of the following should have been done before the report was called:
The clindamycin result should have been removed from the report since it is inactive aginst enterococcus.
Which of the following is the most important variable in the recovery of organisms in patients with bacteremia?
The volume of the blood cultured.
Susceptibility testing is performed on a Staphylococcus aureus isolate from a blood culture with the following results:

oxacillin: resistant

cefazolin: susceptible

Clindamycin: susceptible

erythromycin: susceptible

trimethoprim/sulfamethoxazole: susceptible

vancoumycin: susceptible

What should the technologist do:
the cefazolin result should be changed to resistant since the oxacillin result is resistant
Which of the following combinations of organisms would be appropriate as controls to test the functions listed?
indole -negative Escherichia coli and proteus mirabilis
A urine gram stain shows gram positive cocci in clusters. The organism tested catalase positive. To speciate this organism from culture, the technician should perform a coagulase test and a:
novobiocin susceptibility
The gram stain from a blood culture shows gram positive cocci in chains, No growth occurs on blood agar plates incubated both aerobically and anaerobically. Additional testing should be done to detect the presence of:
Abiotrophia defectica
Viridans streptococci can be differentiated from streptococcus pneumoniae by:
bile soluability
A reliable test for distinguishing Staphylococcus areues from other staphylococcus is:
Which 2 diseases are usually preceded by infection with beta hemoltic streptococci?
glomerulonephritis, rheumatic fever.
The enterotoxin produced by certian strains of hemolytic, coagulase positive Staphylococcus aureus :
causes one type of bacterial food poisioning
Gram positive cocci in chains are seen on a gram stain from a blood culture. The organism grows as a beta hemolytic colony. Further test that could be performed include:
bile esculin, PYR, bacitracin, and hippurate
Of the following bacteria, the most frequent cause of prosthetic heart valve infections occuring within 2-3 months after surgery is:
streptococcus epidermidis
A catherized urine is inoculated onto blood and MacConkey agar using a 0.01 mL loopi. after 48 hours, 68 colonies of a small translucent nonhemolytic organism grew on blood agar but not MacConkey. Testing reveals small gram-positive, catalase negative cocci. The perliminary report and follow up testing would be:
growth of 6,800 colonies/mL of a streptococcus species, esculin hydrolysis and NaCl growth test to follow
Children who have infections with Beta -hemolytic streptococci can develop:
acute glomerulonephritis
A beta-hemolytic Streptococcus that is bacitracin resistant and camp positive is
group B strep
Group B, beta-hemolytic streptococci may be distinguished from other hemolytic streptococci by which of the following procedures?
latex antigen typing
The most critical distinction between Staphylococcus aureus and other Staphylococcus is:
coagulase production
How many hours after eating contaminated food do initial symptoms of staphyloccol food poisioning typically occur
2-6 hours
Which of the following may be used a a positive quality control organism for the bile esculin test.
Enterococcus faecalis
Members of the family enterobacteriaceae share which of the following characteristics:
reduce nitrate to nitrite
A sputum culture from an alcoholic seen in the ER grows gray, mucoid, stringy colonies on sheep blood agar. The isolates grows redily on MacConkey agar and forms mucoid, dark pink colonies. The colonies yield the following test results:
Klebsiella Pneumonaie
An organism gave the following reactions:

TSI: acid slant/ acid butt, no H2S, gas produced

indole: positive

motility: positive

citrate: negative

lysine decarboxylase: positive

Urea: negative

VP: negative

This organism most likely is
Escherecia coli
Shigella species characteristically are:
>100,000 CFU/mL of a gram- negative bacilli were isolated on MacConkey from a urine specimen. Biochemical results are as follows:

glucose: acid, gas produced

indole: negative

urea: positive

TDA: positive

H2S: positive

The organism is most likely:
Proteus mirablis
The stock cultures that needed for quality control of motility are:
Klebsiella pneumoniae/Escherichia coli
The stock cultures that needed for quality control testing of oxidase production are:
Echericheia coli and Pseudomonas aruginosa
The stock cultures that needed for quality control testing of deamination activity are:
Proteus mirabilis and Echericheia coli
The stock cultures that needed for quality control testing of deoxyribonuclease (Dnase) production are:
Serratia marcescens/Echericheia coli
Listeria can be confused with some streptococci because of its haemolyisis and because it is:
esculin positive

Ummm...its a GPB???
A strict anaerobe that produces terminal spores is
clostridium tetani
Gram stain examination of a CSF specimen indicates the presence of yeast like organisms with gram positive granular inclusions . Which of the following techniques should be used next to assist in the identification of this organism?
India ink
Which of the following procedures should be performed to confirm that an unknown mold is one of the pathogenic dimorphic fungi:
culture conversion to yeast form
Lab workers should always work under a biological safety hood when working with cultures of:
coccidioides immitis