Identification of Stenotrophomonas maltophilia in blood cultures by fluorescent in situ hybridization (FISH)

Introduction and Objectives: Stenotrophomonas maltophilia is a serious causative agent for bacteremia. Identification of S. maltophilia in blood cultures using conventional methods requires at least 48 hours, while, rapid identification of causative organism is important to enable satisfactory pathogen-based antibiotic therapy at an early stage. Fluorescent in situ hybridization (FISH) using rRNA-targeted fluorescently labeled probes is a rapid molecular technique for the identification of microorganisms. The objective of this study was to evaluate the FISH for the identification of S. maltophilia in blood culture specimens.Materials and Methods: In this project, 300 blood culture specimens were examined by both FISH and conventional laboratory methods for the detection of S. maltophilia. For analysis of assay, the results of FISH were compared with the results of conventional methods.Result: By conventional cultural and biochemical methods, S. maltophilia was identified in 47 blood culture specimens. FISH identified S. maltophilia in 46 of these 47 S. maltophilia-positive blood culture specimens. Therefore, the sensitivity and specificity of FISH were 97.9% and 100%, respectively.Conclusion: FISH showed a high sensitivity and specificity in our study. These findings suggest that FISH is a suitable technique for the identification of S. maltophilia in blood cultures.

Keywords:

Stenotrophomonas maltophilia , Bacteremia , Blood culture , FISH , Hybridization