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Analysis of factors with low positive predictive value in the diagnosis of urinary tract infection by flow cytometry

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Abstract

Purpose

Culture-negative urine specimens can be rapidly screened by urine flow cytometry (UFC), while low positive predictive value (PPV) limits the clinical application. We explored the factors associated with a low PPV.

Methods

A total of 5095 urine specimens were analyzed with UFC and culture. Diagnostic performance of leukocytes, bacteria, and BACT-info flags was evaluated by sensitivity, specificity, PPV, and negative predictive value (NPV). The association of contaminated culture and squamous epithelial cell count and BACT-info flag was performed by logistic regression analysis.

Results

The NPVs of parallel combination of bacteria and leucocytes were 98.9% in males and 97.9% in females, and PPVs of serial combination were 86.6% and 77.8% in men and women, respectively. The PPV of Gram-negative flag was higher than that of Gram-positive flag. The proportions of contamination in the urine culture results of false positive specimens were 86.9% in males and 98.5% in females at the cutoff points of the serial combination, and these parameters were 53.2% in males and 85.6% in females for the Gram-positive flag. There was a statistically significant association between contaminated cultures and squamous epithelial cells count in females, but not in males. Associations between contaminated cultures and Gram-positive flags or Gram-pos/-neg flags were statistically significant, but there was no association between contaminated cultures and Gram-negative flags.

Conclusions

A serial combination of leukocytes and bacteria may maximize PPV in the diagnosis of bacterial urinary tract infection by urine flow cytometry, and contamination is the main reason for a low PPV.

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Author notes

  1. Guoqiang Zhang and Zhang Dai have contributed equally to this work.

Authors and Affiliations

  1. Center of Clinical Laboratory, Zhongshan Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, 361004, China

    Guoqiang Zhang, Zhang Dai, Yihui Yao, Xiaolu Yu, Ying Gao, Xian-Ming Liang & Meijun Chen

  2. Institute of Infectious Disease, School of Medicine, Xiamen University, Xiamen, 361004, China

    Guoqiang Zhang, Zhang Dai & Xian-Ming Liang

Authors
  1. Guoqiang Zhang
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  2. Zhang Dai
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  3. Yihui Yao
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  4. Xiaolu Yu
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  5. Ying Gao
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  6. Xian-Ming Liang
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Contributions

GZ, ZD, X-ML and MC: conceptualized the study. GZ, MC, YY, YG and XY: collected, analyzed and interpreted the data. GZ and X-ML: conducted the statistical analysis. GZ and ZD: wrote the first draft of the manuscript. All authors revised the manuscript and approved the final version.

Corresponding authors

Correspondence to Xian-Ming Liang or Meijun Chen.

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The authors declare no competing interests.

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No patient specific privacy information is involved, and no patient intervention occurred with the obtained results, therefore do not involve ethics approval.

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Zhang, G., Dai, Z., Yao, Y. et al. Analysis of factors with low positive predictive value in the diagnosis of urinary tract infection by flow cytometry. World J Urol 41, 3611–3618 (2023). https://doi.org/10.1007/s00345-023-04676-6

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  • DOI: https://doi.org/10.1007/s00345-023-04676-6

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