Abstract
Objective: To determine the prevalence of acyclovir-resistant isolates of herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) among Saudi patients.
Design: Culture-isolated strains of HSV- 1 and HSV-2 from Saudi patients were subjected to plaque reduction assay in the presence of various concentrations of acyclovir (ACV).
Setting: Molecular Virology and Infectious Diseases Laboratories of the Research Centre of King Faisal Specialist Hospital and Research Centre in Riyadh, Kingdom of Saudi Arabia.
Subjects: Specimens from Saudi patients attending various clinics in the Hospital were studied retrospectively.
Main outcome measures: The percentage of reduction in the number of plaques when various molar concentrations of ACV were added compared with controls without ACV was used to denote resistance. At ACV concentrations which inhibit susceptible strains, the lower the percentage of plaque reduction the higher the degree of resistance.
Results: At 5 mumol/l acyclovir concentration, 19 of 93 isolates of HSV-1 and 15 of 30 isolates of HSV-2 showed 76-100% plaque reduction. Two of the 30 HSV-2 isolates exhibited 26% and 59% plaque reduction and were from immunosuppressed patients. The prototype strains were fully susceptible at 1 mumol/l acyclovir concentration.
Conclusions: The prevalence of acyclovir-resistant herpes simplex virus strains is very low among Saudi patients. Resistant isolates can be expected from immunocompromised patients. Indiscriminate use of antivirals should be discouraged to minimize the emergence of resistant strains.