The laboratory diagnosis of cytomegalovirus infections

Rapid and accurate diagnosis of cytomegalovirus (CMV) infection is imperative with the advent of effective antiviral therapy (gangiclovir, foscarnet, CMV hyperimmune globin). Applications of conventional cell culture (CC), shell vial assay (SV), serological testing, antigenemia assay (AG) as well as molecular methods [polymerase chain reaction (PCR), branch DNA (b-DNA) and hybrid capture (HC)] to various patient populations and specimen types are discussed. A three year study of 670 specimens [354 urines, 205 peripheral blood leukocytes (PBLs), 56 upper respiratory and 55 tissues] compared CMV CC and SV isolation rates. Of the total, 124 (18.5%) were positive by either or both techniques. For each specimen type the number of positives detected by SV was greater than CC (urine 28 vs 15, PBLs, 12 vs 2). However, of 124 positives, 21 were solely CC positive. A comparison of SV to AG in 230 PBLs yielded a sensitivity of 100% and specificity of 68.3%. The low specificity when compared to SV may be due to the increased sensitivity of AG. Fifty-nine PBLs were examined for differing immunostaining techniques [immunoperoxidase (IP) vs Immunofluorescence (IF)]. IF stained PBLs showed an increased number of positive cells per preparation and greater stain intensity for ease of interpretation.