Peptide Nucleic Acid–Fluorescence In Situ Hybridization for Detection of Staphylococci From Endophthalmitis Isolates: A Proof-of-Concept Study

PURPOSE: Rapid identification of pathogens causing endophthalmitis may improve treatment outcomes through early administration of species-specific medication. The current study reports a new molecular application of peptide nucleic acid–fluorescence in situ hybridization (PNA-FISH) with Staphylococcus-specific molecular PNA probes for the potential rapid detection of common pathogens causing endophthalmitis. METHODS: An experimental study was designed to evaluate the proof of concept at the microbiology laboratory of the Bascom Palmer Eye Institute. Stored culture-positive staphylococci endophthalmitis isolates obtained from prior vitreous samples (n = 15), along with broth as negative controls (n = 5) were used. Inoculum was prepared to a final concentration of 1 × 10(5) colony-forming units/mL to ensure that the isolates were viable. Smears of samples were fixed and hybridized using QuickFISH protocol with probes for Staphylococcus. RESULTS: With PNA-FISH technique, Staphylococcus aureus was identified in 9 of 10 samples and coagulase-negative staphylococci were identified in 10 of 10 samples. Detection time was 20 minutes. CONCLUSIONS: This study serves a proof of concept using a new microbial detection system with FISH probes, and may have the potential for clinical use in the rapid and accurate identification of isolates from patients with endophthalmitis.