Viral resistance and CMV retinitis: design and methods of a prospective study. CRVR Research Groups. Cytomegalovirus Retinitis Viral Resistance Research Group.

A prospective study following a cohort of patients with newly diagnosed, previously untreated cytomegalovirus (CMV) retinitis is being conducted to study drug resistant CMV. Prior to initiation of treatment, patients undergo a baseline eye examination, fundus photography, and blood and urine culture for presence of CMV, and drug susceptibility testing against positive isolates. Patients are followed monthly with a detailed eye examination to diagnose progression of retinitis, and for fundus photography. Cultures are repeated at 1 and 3 months after enrollment, every 3 months thereafter, and at the time of treatment reinduction for the progression of retinitis. This study was designed to determine the prevalence and incidence of drug resistant CMV, as well as risk factors for the development of resistant CMV. It also will determine the correlation between clinical outcome, as measured both by eye examination and fundus photography, and viral resistance.