A 6-year-old child has clustered vesicles on an erythematous base with fever. Varicella-zoster virus infection is suspected and PCR confirmation is requested. The specimen most likely to yield a positive result is:
- A Serum for VZV-specific IgM
- B Urine collected within 24 hours
- C Fluid or cells swabbed from the base of a fresh unroofed vesicle ✓
- D Stool sample for viral culture
Correct answer: C. Fluid or cells swabbed from the base of a fresh unroofed vesicle
Explanation
Vesicle fluid and epithelial cells scraped from the base of a fresh lesion contain the highest concentration of cell-associated VZV and are the specimens of choice for PCR or direct fluorescent antibody testing. VZV IgM rises only after several days and may persist or recur, so it is less specific for acute disease. Urine and stool are not useful specimens for VZV diagnosis.
Reference: Ananthanarayan and Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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