Abstract
Purpose :
Infectious keratitis (IK) is the leading cause of corneal blindness globally. Timely diagnosis is essential for achieving a good clinical outcome but current microbiology culture method is limited by variably low yield and slow turnaround time. This study aimed to compare the diagnostic performance of microbiological culture and polymerase chain reaction (PCR)-based molecular test for diagnosing infectious keratitis.
Methods :
This was a retrospective, comparative diagnostic clinical study. All patients presenting to Queens Medical Center, Nottingham, with presumed IK who underwent microbiological culture (either direct culture, indirect culture, or both) and 16S/18S PCR (using eSwab) between June 2021 and September 2022 were included in this study. Agreement among tests were examined using Cohen’s Kappa statistic (k).
Results :
A total of 86 cases of corneal sampling were included from 81 patients (including 5 cases of repeated sampling). The mean age was 49.7 ± 22.7 years, and 41 (50.6%) were female patients. Direct culture, indirect culture, and PCR had a positive yield of 53.0%, 48.2%, and 41.9%, respectively (p=0.127). The most common organisms were Pseudomonas aeruginosa and coagulase-negative Staphylococcus species. Of 31 culture-negative cases, PCR was able to identify the causative microorganisms in 3 (9.7%) cases. On the patient level (for a positive result), PCR showed substantial agreement with both direct culture (k=0.64±0.09; p<0.001) and indirect culture (k=0.72±0.08; p<0.001). On the organism genus level, there was a moderate-to-substantial agreement between PCR and direct culture (k=0.55±0.10; p<0.001) and indirect culture (k=0.61±0.08; p<0.001), respectively.
Conclusions :
This study highlights that PCR has a similar diagnostic performance as current microbiology culture method and may serve as a useful adjunctive diagnostic modality for enhancing the diagnostic yield for IK.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.