An outbreak of severe diarrhea occurs in an intensive care wing of a major hospital. As a result, the patients are all screened for colonization and infection by the pathogenic organism. However, not all of the patients identified carrying the organism by phenotypic identification and characte-rization are displaying symptoms of infection. The reason for this discrepancy is:
a. some patients have a stronger immunity to the pathogenic organism.
b. the patients who are not displaying symp-toms have been on antibiotics and the or-ganism has mutated and is no longer pa-thogenic.
c. the patients are not all infected with the same strain of the organism that is carrying the enteric toxin causing the diarrhea.
d. the laboratory has likely misidentified the organisms.
A D-test is set up on a S. aureus isolate. There was no zone around the Erythromycin disk and the zone of inhibition around the clindamycin disk adjacent to the erythromycin disk was inter-preted as susceptible. Thus, the resistance mechanism for the erythromycin is due to:
a. altered target.
b. increased efflux.
c. decreased porin channels.
d. degradative enzymes.
During the process of phlebotomy, drawing a blood specimen from a patient, the action of cleaning the area on the skin prior to the insertion of the needle requires the application of a(n):
a. chemical sterilant.
b. bacteriostatic agent.
c. alcohol.
d. antiseptic.
The ability of two nucleic acid strands, a probe and a target, which have complementary base sequences that specifically bond with each other and form a double-stranded molecule, drives which of the following methods?
a. Hybridization
b. Sequencing
c. Amplification (PCR)
d. Genotypic
Clinical sensitivity in the microbiology laboratory refers to:
a. positive results from patients known to have an infection or disease.
b. percentage of positive results from all pa-tients tested.
c. percentage of patient's that test negative known to have an infection or disease.
d. none of the above answers are correct.
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