Gut Colonisation and Multidrug-Resistant Urinary Tract Infections in Hospitalised Kidney Transplant Recipients: A...

Background/Objectives: Urinary tract infections (UTIs) represent the most common infectious complication following kidney transplantation. An increasing number of UTIs are caused by multidrug-resistant organisms (MDROs). The role of intestinal MDRO colonisation in complicated urinary tract infections (cUTIs) among kidney transplant recipients is not fully understood. Methods: We conducted a retrospective, single-centre study of kidney or kidney-pancreas transplant recipients hospitalised for infectious diseases. Each hospitalisation was analysed as a separate event. Routine rectal screening targeted carbapenem-resistant Enterobacterales and vancomycin-resistant/vancomycin-variable enterococci. Results: The study included 65 hospitalisations from 52 kidney transplant recipients, with some patients contributing multiple admissions. cUTIs accounted for 63.1% of admissions, and 22.0% of cUTIs were associated with concomitant bloodstream infection (BSI). The most frequently isolated pathogens were Klebsiella pneumoniae (58.8%) and Escherichia coli (41.2%). Extended-spectrum β-lactamase (ESBL) production was detected in 50% of E. coli isolates, while carbapenemase production was identified in 60% of K. pneumoniae isolates. MDRO rectal carriage was detected in 43.1% of cases and was more frequent in cUTI than in other infections (53.7% vs. 25.0%, p = 0.024). Carbapenemase-producing K. pneumoniae (CP-KP) rectal carriage was also more frequent in cUTI (31.7% vs. 4.2%, p = 0.011), but did not remain statistically significant after adjustment for urinary stent presence (odds ratio 7.1, 95% CI 0.7-66.2; p = 0.087). Nevertheless, CP-KP rectal carriage was associated with CP-KP cUTI aetiology (PPV 75.0%; NPV 86.4%). The median length of hospital stay (LoS) was 15 days. In multivariable analysis, a longer median LoS was associated with BSI (12.2 days; 95% CI: 0.8-23.6; p = 0.037), urinary stent presence (6.8 days; 95% CI: 1.5-12.2; p = 0.014), and older age (2.3 days; 95% CI: 0.7-4.0; p = 0.007). Conclusions: Rectal CP-KP colonisation may represent a potential marker of cUTI risk, although its independent association was not confirmed after adjustment. These findings should be interpreted with caution, given the study design and sample size and require confirmation in larger prospective studies. Rectal screening may contribute to early risk stratification, whereas its role in guiding empirical therapy remains to be prospectively evaluated.