FilmArray® multiplex PCR panels on corneal swabs in suspected infectious keratitis: a pragmatic real-world study

To evaluate the clinical utility of a pragmatic, off-label multiplex PCR strategy using FilmArray® panels on corneal swabs in suspected infectious keratitis, with emphasis on diagnostic yield, turnaround time, and early therapeutic impact in routine care.

This prospective, single-center observational study was conducted over 24 months (January 2024-December 2025) at a tertiary referral center. In episodes of clinically suspected infectious keratitis, corneal swabs were immersed in brain-heart infusion medium. A FilmArray® Meningitis/Encephalitis (ME) panel was used as first-line testing, with selective FilmArray® Blood Culture Identification 2 (BCID2) panel use when clinically indicated. Conventional bacterial and fungal cultures were systematically performed. Outcomes included diagnostic yield of the PCR algorithm, turnaround time (TAT), concordance patterns with culture, and early treatment changes after PCR results.

Fifty episodes were included. The multiplex PCR algorithm (ME ± BCID2) detected at least one pathogen in 50% of cases, with viral detections, mainly herpes simplex virus type 1, accounting for a substantial proportion of PCR-positive results. Conventional culture was positive in 32% of cases and identified bacterial and/or fungal pathogens. Median TAT was 6.5 h for PCR versus 79 h for culture, corresponding to a median reduction of 72.5 h. PCR findings were associated with treatment modification within 24 h in 32% of cases, with additional changes after 48 h in 6%, predominantly antiviral initiation or targeted antimicrobial adjustment.

In this real-world exploratory study, the main advantage of the pragmatic FilmArray® strategy was the marked reduction in turnaround time compared with culture, providing microbiological information within hours rather than days. Because PCR and culture differ fundamentally in detectable pathogen classes, particularly due to viral detection by PCR, these findings should not be interpreted as evidence of diagnostic superiority. FilmArray® testing may serve as a complementary approach in selected severe, atypical, pretreated, or culture-negative keratitis cases when rapid therapeutic decisions are needed.