INVESTIGATION OF RESPIRATORY SYNCYTIAL VIRUS BY THREE DIFFERENT METHODS IN CHILDREN WITH LOWER RESPIRATORY TRACT INFECTION

Respiratory Syncytial Virus (RSV) is the most important viral agent leading to lower respiratory tract infection in infants and children. The aim of this study was to investigate the presence of RSV by direct immunofluorescence antibody (DFA), cell culture and polymerase chain reaction (PCR) in children with lower respiratory tract infection. Nasotracheal aspirate specimens collected from 80 hospitalized patients aged between 0-24 months and clinically diagnosed as lower respiratory tract infection, during November 2005-May 2006 period, were included to the study. RSV antigen was investigated in clinical specimens by DFA method (Monofluo Bio-Rad, France). Hep-2 culture was used for isolation of RSV. RSV-RNA was investigated by real-time PCR (Fluorion lontek, Turkey) in clinical specimens. RSV was found positive in 26 (32.5%) of 80 samples by DFA and in 17 (21.3%) samples by cell culture. Six specimens were not studied by PCR as sample amounts were not sufficient. Of the 74 samples tested, 20 (27%) were found to be positive by real-time PCR. Fifty-four of the samples were negative by 3 of the methods, while 12 were positive by all of them. DFA and PCR positive 8 samples yielded negative result in cell culture. Five of the 6 samples not investigated by PCR, were positive both in DFA and cell culture while I sample was positive only by DFA. Considering cell culture as the gold standard, the sensitivity, specificity, positive and negative predictive values were found as 100%, 85.7%, 65.4% and 100%, respectively, for DFA and 100%, 94.7%, 85% and 100%, respectively, for PCR. As a conclusion for the accurate diagnosis of RSV infections the clinical samples should be collected in the early phase of the disease and inoculated to the cell cultures immediately for viral isolation. If cell culture or PCR facilities are not available for routine diagnosis, DFA method can be used for rapid and cost effective diagnosis of RSV infections.