Clin Chem Lab Med. 2026 Jul 14. doi: 10.1515/cclm-2026-0684. Online ahead of print.
ABSTRACT
OBJECTIVES: Peritonitis is a feared complication to peritoneal dialysis (PD), requiring empirical broad-spectrum antibiotics. A rapid method to predict culture positivity and bacterial Gram classification could enable earlier targeted therapy and reduce unnecessary antibiotic exposure. This study evaluated the diagnostic performance of the automated flow cytometer Sysmex UF-5000 for cell counts and Gram classification in suspected PD-related peritonitis.
METHODS: Adults (>18 years) with suspected PD-associated peritonitis admitted to Aarhus University Hospital were included. Peritoneal dialysis fluid (PDF) was analysed using the UF-5000. Cell counts, bacterial counts, and Gram classification were compared with culture results. White blood cell (WBC) counts were additionally compared with Sysmex XN-9000.
RESULTS: Fifty-two episodes in 39 patients were analysed; 71 % were culture-positive. Bacterial and WBC counts on the UF-5000 were strongly correlated. WBC count in urine mode was the only parameter significantly associated with culture positivity (AUC 0.79), but several culture-negative cases had high WBC and bacterial counts. Gram classification was unreliable with 65 % of culture-positive samples unclassified and 31 % of the remainder misclassified. Agreement between the UF and XN WBC counts in body fluid mode was good (bias 7.6 %), whereas UF urine mode showed substantial negative bias for both WBC and bacterial counts compared with body fluid mode.
CONCLUSIONS: WBC count was the best predictor of culture positivity. Gram classification by UF-5000 urine mode was unreliable in PDF. The body fluid mode on the UF or XN is recommended for PDF analysis due to apparent interference in UF urine mode.
PMID:42443141 | DOI:10.1515/cclm-2026-0684