Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1342 page)

   Interpretation

   
Expected results:
Negative.

   Limitations

   Examination of several specimens improves detection in patients with light infection. A series of O & P examinations is recommended in patients with repeatedly negative immunoassays in whom parasitic infection is still suspected.

Suggested Readings

CLSI.
Procedures for the Recovery and Identification of Parasites from the Intestinal Tract; Approved Guideline
, 2nd ed. CLSI document M47-A. Wayne, PA: Clinical and Laboratory Standards Institute; 2005.

Garcia LS.
Diagnostic Parasitology
, 5th ed. Washington, DC: ASM Press; 2007.

CYTOMEGALOVIRUS (CMV) CULTURE (RULE OUT)

   Definition and Use

   CMV is a ubiquitous viral pathogen. Most infections in immunocompetent patients are asymptomatic or mildly symptomatic, including a self-limited mononucleosis syndrome. In immunocompromised patient populations, including neonates, patients with AIDS, and transplant patients, serious localized (e.g., retinitis, colitis, polyradiculopathy, encephalopathy) or systemic infection may occur.

   
Method:

   Specimens for CMV culture are usually inoculated onto monolayers of human fibroblasts (e.g., foreskin, fetal lung). Tube cultures should always be inoculated for CMV cultures. The shell vial cultures may also be inoculated. Shell vial cultures provide a more rapid turnaround time than tube cultures but are somewhat less sensitive for detection.

   Presumptive CMV infection may be inferred by typical cytopathic effect, but positive cultures should be confirmed by immunologic techniques, such as DFA staining with CMV-specific reagents.

   
Turnaround time:
Specimens with high viral loads, such as urine, may give positive results within several days, but negative cultures may require incubation for up to 4 weeks before signing out as negative. Shell vial cultures are processed for growth at 48–72 hours after inoculation.

   Special Collection and Transport Instructions

   Specimens should be collected according to general recommendations for virus culture of the specimen type.