Rapid detection of Pseudomonas aeruginosa in clinical samples of burned patients by Fluorescent in situ hybridization(FISH)

Pseudomonas aeruginosa is one of the most important opportunistic pathogens in patients who suffer from immunodeficiency and burns. Wound infections caused by P.aeruginosa can rapidly change to systemic and life threatening situation. The aim of this study was to apply florescent in situ hybridization (FISH) method for rapid detection of P. aeruginosa in burrn patients. This study was performed on 100 samples of wound and blood from burn patients at Taleghani Hospital in Ahwaz. The samples were used for both bacterial culture and FISH assays. To use FISH technique, the samples were probed with the complementary sequences to specific region of 16 S rRNA. The probes were FITC- labeled pB-00375 specific for pseudomonas genus; CY3-labeled pb-00384 specific for P. aeruginosa and EUB-338 as a eubacterial probe. Due to labeling of the probes with fluorescent die, the fluorescent signals appeared shining after hybridization of the probes with the organism under the fluorescent microscope. Of 42 blood samples, 13 were positive for Pseudomonas in culture. Only one culture positive sample was recognized as negative by FISH. Sensivity and specificity of FISH for detection P. aeruginosa in blood samples was 94.7% and 100% respectively. FISH could detect all 20 culture positive samples from wounds corresponding to sensitivity and spicifity of 100% and 93/3% respectively. When rapid diagnosis of infectious agents is required, FISH can be used as sensitive technique for detection of causative organism with a complete process of 3 hours. Moreover, due to visibility of morphology of infected organism in “FISH”, recognition of infecting agent will be achieved confidently.