A novel culturing system for fluid samples

Background: Large-volume culture methods for sterile body fluids employing automated blood-culture systems increase the recovery of microorganisms compared with traditional plate medium methods. However, in many instances a laboratory receives only small-volume samples. Materials/Methods: The URO-QUICK (TM) system (now HB&L), originally used to process urine samples, was evaluated for organism enrichment and determination of microbial count of fluid samples. Fluid specimens were also evaluated for their residual antimicrobial activity (RAA). The procedures were compared with results from a conventional culture procedure. The 546 samples included 106 endotracheal aspirate, 63 bronchoalveolar lavage, 139 sputum, 47 blood, 105 pleural fluid, 26 cerebrospinal fluids, and 41 peritoneal fluid samples as well as 19 other fluids including synovial fluid (n=5), ascitic fluid (n=9), fluids from the drainage of an infected central venous catheter (n=3), abdominal drainage fluid (n=1), and cholecystic fluid (n=1) Results: The URO-QUICK (TM) system allowed the culture of an additional 44 samples (8%, p=0.007) compared with the traditional culturing method. The RAA test demonstrated good concordance with the reference method, showing specificity and positive predictive value of 100% for each, while the sensitivity and the negative predictive value were 67% and 76%, respectively. The microbial counts evaluated using the URO-QUICK (TM) system showed excellent agreement with traditional enumeration methods. Conclusions: The URO-QUICK (TM) system may well represent an excellent alternative to solid medium-based recovery and enumeration methods.