Predictive Value of Urinalysis and Recent Antibiotic Exposure to Distinguish Between Bacteriuria, Candiduria, and No-Growth Urine

Abstract

Darunee Chotiprasitsakul,1 Akara Kijnithikul,1 Anuchat Uamkhayan,2 Pitak Santanirand2 1Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; 2Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, ThailandCorrespondence: Darunee ChotiprasitsakulDepartment of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, 270 Rama VI Road, Bangkok, 10400, ThailandTel [phone]Fax [phone]Email [email protected]: Urinary tract infections are diagnosed by clinical symptoms and detection of causative uropathogen. Antibiotics are usually not indicated in candiduria and no-growth urine. We aimed to develop a predictive score to distinguish bacteriuria, candiduria, and no-growth urine, and to describe the distribution of microorganisms in urine.Patients and Methods: A single-center, retrospective cohort study was conducted between January 2017 and November 2017. Patients with concomitant urinalysis and urine culture were randomly sorted for a clinical prediction model. Multivariable regression analysis was performed to determine factors associated with bacteriuria, candiduria, and no-growth urine. A scoring system was constructed by rounding the regression coefficient for each predictor to integers. Accuracy of the score was measured by the concordance index (c-index).Results: There were 8091 positive urine cultures: bacteria 85.6%, Candida 13.7%. Randomly selected cases were sorted into derivation and validation cohorts (448 cases and 272 cases, respectively). Numerous yeast on urinalysis predicted candiduria with complete accuracy; therefore, it was excluded from a score construction. We developed a NABY score based on: positive nitrite, 1 point; Antibiotic exposure within 30 days, – 2 points; numerous Bacteria in urine, 2 points; few Yeast in urine, – 2 points; moderate Yeast in urine, – 5 points. The c-index was 0.85 (derivation) and 0.82 (validation). A score ≥ 0 predicted 76% and 54% of bacteriuria in the derivation and validation cohorts, respectively. A score ≤− 3 predicted 96% of candiduria in both cohorts.Conclusion: Numerous yeast on urinalysis and the NABY score may help identify patients with a low risk of bacteriuria in whom empiric antibiotics for UTIs can be avoided.Keywords: urinary tract infection, Candida, antibiotics, microscopy, urine culture, NABY score

Keywords

• urinary tract infection
• candida
• antibiotics
• microscopy
• urine culture
• naby score