Comparison between urine culture profile and morphology classification using fluorescence parameters of the Sysmex UF-1000i urine flow cytometer.

AIMS

To determine the usefulness of the fluorescence parameters generated by Sysmex UF-1000i flow cytometer for the rapid diagnosis of urinary tract infection by bacilli or cocci.

METHODS AND RESULTS

Urine samples (n = 1924) were studied by culture and microbiology and subsequently by cytometry, using BACT-Morph software and considering forward-scattered light (FSC) and fluorescent light scatter fluorescence parameters. BACT-Morph software showed moderate diagnostic accuracy (78·4%) to detect rod-shaped bacteria, with sensitivity of 82·4% and specificity of 62·5%. Forward-scattered (B_FSC) values of the bacterial channel were significant higher for the Gram-positive cocci category (P < 0·001). A cut-off of B_FSC ≥24·2, expressed in arbitrary units (analytical channel, ch), provided higher sensitivity (90·0%) but lower specificity (38·9%), and the diagnostic accuracy for Gram-positive cocci classification reached 62·0%.

CONCLUSIONS

Utilization of BACT-Morph software and bacterial channel fluorescence parameters (B_FSC ≥24·2 ch) offered an approximate discrimination of bacilli and cocci but the specificity was low, especially for FSC.

SIGNIFICANCE AND IMPACT OF THE STUDY

Further research is needed to establish the usefulness of flow cytometry for aetiological diagnosis.