Prevalence Of Pathogens in Intensive Care Unit Patients with Lower Respiratory Tract Infections: Culture With/Without Polymerase Chain Reaction?

The lower respiratory tract infections (LRTI) are a leading cause of hospitalization and death globally [1]. The early initiation of appropriate antibiotics in patients with LRTI is crucial as postponing effective antibiotic administration can adversely affect the prognosis [2,3]. Therefore, diagnostic studies establishing the microbial etiology of LRTI are fundamental to provide effective therapy and administration of appropriate antibiotics to the patients [4,5]. Currently, antimicrobial therapy of LRTI is typically initiated on an empirical basis, because of the traditional diagnostic methods including standard culture and antigen detection assay are not able to detect significant proportion of causative pathogens [6,7]. In addition, standard culture and antibiotic susceptibility tests are time-consuming processes, which require at least 24-48 hours [8]. It is known that delay in antibiotic administration is associated with increased in-hospital mortality, especially in severe infections such as pneumonia [9]. Over the last few years, molecular techniques have emerged as the diagnostic tool of choice for respiratory microorganisms, particularly for viruses, fastidious bacteria (H. influenza, S. pneumonia etc) with difficulty in growing in culture plates, less viable or present in only small number [4,10]. These molecular techniques are also less likely to be affected by the administered empirical or prior antibiotic than standard culture [11,12]. In addition, molecular techniques are able to detect the causative microorganism more quickly than the standard culture methods and that may expedite the better-targeted antimicrobial treatment and improve the antibiotic stewardship [11,13]. The aim of our study is to evaluate the utility of a comprehensive molecular diagnostic approach encompassing 7 respiratory bacterial and 15 viral pathogens in tracheal aspirate culture in patients with suspected LRTI during intensive care unit (ICU) stay.