Virus detection, culture

Last updated: Sunday, 28, May, 2006

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Item Process
Specimen

Lesion swab, vesicle fluid, conjunctival swab, nasopharyngeal aspirate, throat swab, CSF, tissue biopsy, faeces, urine, blood leucocytes (5 mL blood in EDTA or heparin).

Specimens should be collected as soon as possible after the onset of illness.

Aspirates are better than swabs whenever practicable.

Aspirates and swabs should be placed in viral transport medium.

Specimens require careful sterile collection, and rapid transport to the laboratory.

If nucleic acid detection after amplification is used, a dry swab may be preferred and rapid transport is less critical.

Consult laboratory for local requirements.

Method

A clear clinical description of the illness on the request form allows selection of the most appropriate technique(s).

Microscopy (DFA) for eg, HSV in vesicle aspirate or ulcer scrapings, respiratory pathogens in nasopharyngeal aspirates; EM.

Culture in cell culture systems (in which growth is detected by observing for indications of viral growth eg, cytopathic effects on microscopic examination, haemadsorption.

Nucleic acid probes - including use after PCR amplification (may be used directly on the specimen for rapid virus detection and identification, providing a much faster result than culture).

See Molecular genetics - microbial.

Application

Investigation of:
genital ulcers;
oral ulcers;
vesicular skin lesions (especially if severe, atypical or in a neonate);
conjunctivitis;
severe bronchiolitis;
severe croup;
atypical or viral pneumonia;
aseptic meningitis;
encephalitis;
myocarditis;
suspected congenital infection (eg, rubella, CMV);
suspected poliomyelitis; and
rotavirus infection.

Investigation of a suspected new influenza epidemic.

Interpretation

Detection of viral antigen or inclusions, or isolation of virus, implies current infection though it may not be the cause of symptoms.

Interpretation requires an understanding of the natural history of viral infections; consult pathologist.

Reference

Forman MS and Valsamakis A. In: Murray PR et al eds. Manual of Clinical Microbiology. 8th ed. ASM Press 2003.