D-119. Rapid PNA FISH Protocol Modification for Detection of Staphylococci

M. Morgan, A. Deirboghossian, E. Youssef;
Cedars Sinai Med. Ctr., Los Angeles, CA.

Background: The S. aureus/CNS PNA FISH kit (AdvanDx, Inc.) provides a robust and easy to use species identification method for use directly from blood culture bottles. Although already rapid, the method requires a long (1.5 hour) hybridization step which can be inconvenient. We validated a modified PNA FISH protocol to reduce the hybridization time, and decrease the time to result. Methods: A side-by-side comparison was performed using the protocol in the package insert and a modified protocol where the ethanol fixation step was eliminated and the hybridization step was reduced to 30 minutes (from the previous 90 minutes). We compared 42 samples prepared directly from positive blood culture bottles (Bactec 9240, Standard 10 Aerobic and Anaerobic F bottles). Results: S aureus/CNS PNA FISH correctly identified 100% (42/42) of Gram positive cocci in clusters in samples compared to culture using both the package insert protocol and the modified protocol. The assay sensitivity for both protocols was 100%, 10/10 for S aureus and 32/32 for CNS). The intensity of fluorescence for the slides stained with the modified protocol often times exceeds that of the package insert protocol. Conclusion: We found the PNA FISH method can be performed with the modified protocol without negatively affecting the sensitivity or specificity of the assay.

274/D. Animal Models and Vaccine Approaches for Pathogenic Bacteria

Wednesday, 1:00 pm | Poster Hall