Performance evaluation of UF-4000 body fluid mode for detection of bacteria in body fluids

Microbiological analysis of body fluids (BF) provides important information for diagnosis of infection. We evaluated the analytical performance of bacterial count by UF-4000 BF mode for ascitic, cerebrospinal, pleural, synovial and continuous ambulatory peritoneal dialysis fluids compared to classical microbiological procedure (direct Gram staining and culture).

For the 1,734 BF analyzed, distribution of UF-4000 bacterial count was analyzed according to the level of growth culture and results were compared using Mann-Whitney test. ROC curves analysis allowed to define the best cut-off value to predict or exclude positive culture for each type of BF.

UF-4000 bacterial counts were significantly lower in sterile than in infected BFs (p < 0.00001) and correlated with the level of growth on culture. The ROC curves of bacteria/μL and culture positivity yielded area under the curve >0.80 for each type of BF. Optimal cut-offs were chosen with excellent statistical parameters (sensitivity ranging from 0.70 to 0.86, specificity from 0.78 to 0.98, negative predictive value >0.95 and Youden index >0.55).

For BF, UF-4000 bacterial count correlate with culture results and is a discriminative method enhancing detection of microbiological etiology. It could be used as a screening method based on the cut-off values proposed in this study.