Objectives: Specialized analyzers are used to automate the diagnosis of bacteriuria in laboratory practice. They are based on analysis of microorganisms concentration in urine samples or recording the growth of urine microflora. Coherent fluctuation nephelometry (CFN) has high sensitivity and allows analyzing both parameters simultaneously. The aim of the study is to compare the effectiveness of CFN-based and flow cytometry based analyzers.
Design and methods: Total 117 urine samples from children were studied in parallel using the CFN-analyzer and UF-1000i (Sysmex), the results were confirmed by conventional microbiological methods.
Results: In 21 urine samples (18%), significant bacteriuria was determined (≥104 CFU/ml). The best diagnostic indicators were obtained while testing urine samples using the CFN-analyzer. The most efficient bacteriuria diagnosis is achieved by simultaneous analyses of microorganisms concentration in urine and growth of urine microflora (sensitivity - 95.2%, specificity - 96.9%, positive predictive value - 87%, negative predictive value - 98.9%, diagnostic odds ratio - 81.7, positive likelihood ratio - 30.5, negative likelihood ratio- 0.049, area under curve in ROC-analysis - 0.987). The CFN-analyzer allows the preliminary selection of negative urine samples, which do not require further analysis by conventional microbiological methods, thereby decreasing the number of cultures by 80.3%.
Conclusions: This study suggests that the CFN-analyzer is the effective tool for bacteriuria screening in children.
Keywords: AUC, area under curve; B, bacteriuria; Bacteriuria; CFN, coherent fluctuating nephelometry; CFU, colony forming units; Children; Coherent fluctuation nephelometry; G, growth time; T&G, function of turbidity and growth time; T, turbidity; TN, traditional nephelometry; UF-1000i; UTI, urinary tract infections; Urinary tract infection.