Identification of causative and non-causative microorganisms of nephrostomy tube-associated pyelonephritis among patients with malignancy.

Background: Prolonged installation of a nephrostomy tube causes colonization of various microorganisms within the lumen of the tube, leading to the development of nephrostomy tube-associated pyelonephritis (NTAP). Patients with malignancy, often necessitating long-term installation of a nephrostomy tube, are susceptible to NTAP. However, information regarding the characteristics of NTAP in this population is limited.

Methods: We reviewed 43 NTAP cases of patients with malignancy in a cancer center and examined causative and non-causative microorganisms among those detected in urine culture. Causative microorganisms were defined as (1) those detected simultaneously in urine and blood cultures or (2) those detected in monomicrobial urine culture and to which physicians administered active antimicrobials for ≥5 days. Non-causative microorganisms were defined as those to which active antimicrobials were given for a total of <5 days.

Results: Patients in 42 of the 43 NTAP cases recovered with antimicrobial therapy for ≥7 days. Causative microorganisms were identified in 25 cases, where Escherichia coli and Klebsiella pneumoniae were most frequent. All enterococci other than Enterococcus faecalis, Corynebacterium species, and Candida species other than Candida albicans and most of Stenotrophomonas maltophilia detected in urine culture were considered non-causative of NTAP.

Conclusion: E. coli was a common organism causing NTAP of this population. Several microorganisms resistant to cephalosporin were non-causative of NTAP, for which administration of antimicrobials may be unnecessary even if detected in urine culture.