Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1438 page)

   Limitations

   Specimens must be collected, transported, tested, and interpreted using protocols described in the package insert of the kit used.

   Performance of the test depends on optimal specimen collection.

   Negative results do not exclude the possibility of infection with any of the specific pathogens.

   Alternative testing, like pH, “amine test,” and microscopic examination of vaginal fluid may be considered for the evaluation of patients.

   The Affirm VPIII test does not detect infection by
Neisseria gonorrhoeae
or
Chlamydia trachomatis
; these pathogens and other possible causes of the patient’s symptoms should be considered, and ruled out as appropriate, in women presenting with vaginal discharge or other compatible symptoms.

   The test cannot be used as a test of cure because DNA from nonviable pathogens may be detectable after resolution of infection.

VANCOMYCIN-RESISTANT ENTEROCOCCUS (VRE) SCREEN CULTURE

   Definition and Use

   This test is usually ordered to detect VRE carriage in asymptomatic patients for infection control purposes. It is indicated to screen patients at risk for self-infection or for transmitting VRE to close contacts. The test may also be requested to document clearance of VRE carriage. A patient specimen is plated onto selective agar, typically containing 6 μg/mL vancomycin. Any growth of
Enterococcus
likely represents VRE, but vancomycin resistance and identification should be confirmed by subsequent testing of the isolate. Swab specimens of the rectum or perianal skin are recommended for VRE screening cultures.

   
Turnaround time:
48 hours.

   Interpretation

   
Expected results:
Negative.

   Limitations