The role of temperature and swab materials in the recovery of herpes simplex virus from lesions.

Abstract

swab was placed in 2 ml of Eagle's minimal essential medium containing a 1%07 mixture of penicillin, streptomycin, amphotericin B, and 207% bovine serum. The specimens were left at room temperature for 15-30 min; two 0.2-ml samples from each specimen were then inoculated into tubes containing human embryonic lung fibroblasts. The remaining medium was divided; half of the medium was refrigerated at 4 C and half was frozen at - 20 C for 48 hr. During the first part of the study, the swabs were retained in the specimens; during the second half of the study, the swabs were removed from the specimens and discarded before storage. After 48 hr the refrigerated and frozen specimens were brought to room temperature, and two 0.2-ml samples from each specimen were inoculated onto human embryonic lung fibroblasts. All of the cultures were incubated at 35-37 C and examined daily for 10 days for CPE. The positive cultures were harvested and typed according to the method of Stewart and Herrmann [1]. The X2 test was used for statistical comparison. * P< 0.001. t P< 0.01. $ P< 0.01. S P< 0.01. II P< 0.01. Summary Swab specimens of lesions from patients attending a sexually transmitted disease clinic that were thought to be caused by HSV were cultured to determine whether recovery of HSV was influenced by the use of cotton swabs vs. calcium alginate swabs and by storage of the specimens at refrigerator temperature (4 C) vs. freezer temperature (- 20 C). Adverse effects by both the use of calcium alginate swabs and the storage of specimens at freezing temperatures have been reported for laboratory-prepared stock cultures of HSV [2, 3] but not for clinical specimens. Fifty-one (62.1%) of the 82 patients who were cultured were positive for HSV; 46 isolates were HSV type 2 and five were HSV type 1. There was no difference in the recovery of HSV from cotton or calcium alginate swabs if the samples were inoculated immediately. However, if the samples were stored, the percentage of