Evaluation of the shell vial technique for detection of ocular adenovirus. Community Ophthalmologists of Pittsburgh, Pennsylvania.

PURPOSE: The shell vial technique is a cell culture method that uses centrifugation and immunofluorescence to decrease the time required for a positive test. The authors evaluated the shell vial technique as a diagnostic test to detect adenovirus in conjunctival specimens of patients with adenoviral conjunctivitis.

DESIGN: Retrospective and prospective case series.

PARTICIPANTS: Forty-six patients with adenoviral culture-positive ocular infection.

METHODS: The minimum time of incubation (days) that was required for testing clinical isolates with the shell vial was determined with adenovirus serotypes 5 and 8. In a masked retrospective study, 25 true-positive (frozen clinical samples) and 25 true-negative specimens were tested for the presence of adenovirus using the shell vial technique. The 25 true-negative samples included herpes simplex virus, Chlamydia trachomatis, Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus. In a prospective study, 21 patients who later tested positive in cell culture for adenovirus were concurrently tested with shell vial.

MAIN OUTCOME MEASURES: The time of incubation was determined in days, and the sensitivity, specificity, positive and negative predictive values, and the efficacy of the shell vial test were determined.

RESULTS: The minimal time of incubation for testing ocular samples by shell vial was 3 days. In the retrospective study, the sensitivity, specificity, positive predictive value, negative predictive value, and efficacy were 92%, 100%, 100%, 93%, and 96%, respectively. Comparably (P = 0.99), in the prospective study the sensitivity, specificity, positive predictive value, negative predictive value, and efficacy were 95%, 100%, 100%, 96%, and 97%, respectively. The shell vial (93%, 43 of 46) was equivalent (P = 0.42) to cell culture (100%, 46 of 46) for detecting adenovirus, but a positive result was obtained in significantly less time (3 days versus 9.41 +/- 6.23 days) (P = 0.00001).

CONCLUSIONS: The shell vial technique was found to be a definitive method for identifying adenovirus from ocular specimens. A clear benefit for the ophthalmologist is that the test can provide a faster positive result (3 days) compared with conventional cell culture, which can take 1 to 3 weeks for adenovirus isolation.