Epidemic keratoconjunctivitis in a university medical center ophthalmology clinic; need for re-evaluation of the design and disinfection of instruments

Abstract

During the period from early December 1987 to late January 1988, an outbreak of epidemic keratoconjunctivitis (EKC) caused by adenovirus type 8 occurred at a university medical center eye clinic. A telephone survey of patients revealed an attack rate of 17% among patients seen during the epidemic period. A case-control study demonstrated that development of EKC was associated with exposure to pneumotonometry and to three caregivers. After controlling for exposure to pneumotonometry, however, only exposure to one caregiver was significantly associated with risk of the disease. On January 19, 1988, after recognition of the outbreak, the eye clinic instituted additional infection control measures. A survey of patients seen the following week showed a substantial decrease in the attack rate (1.9%). Before these control measures were implemented, clinic personnel had followed the manufacturer's recommendations and disinfected pneumotonometer tips with 70% isopropyl alcohol, fearing that other disinfectants would corrode the instrument metal. Isopropyl alcohol, shown to have limited activity against adenovirus in vitro, also was being used to "disinfect" pneumotonometer tips between uses at six other area eye clinics polled by telephone. The results of this study demonstrate the need for changes in the design and manufacture of equipment used in the eye clinic.