Host and pathogen factors in Klebsiella pneumoniae upper urinary tract infections in renal transplant patients.

Purpose: To analyse the role of virulence factors (VFs) and host in Klebsiella pneumoniae upper urinary tract infections (UTIs) in renal transplant (RTx) recipients.

Methodology: Clinical and demographic data were registered prospectively. Phylogenetic background of K. pneumoniae isolates was analysed by PCR melting profiles (MP) and the following VFs genes: fimH-1, uge, kpn, ycfM, mrkD, rmpA, magA, hlyA, cnf-1, irp-1, irp-2, fyuA, entB, iutA, iroN by PCR.

Results: We studied urine cultures and clinical data from 61 episodes of K. pneumoniae UTI in 54 RTx recipients. There were 32 cases of AB (53%), 10 cases of lower UTI (16%), 19 cases of AGPN (31%), including six cases of bacteraemia. In total, 74 % of strains were extended-spectrum beta-lactamase+, and there were two carbapenemase-producing strains. PCR MP typing showed a diverse population with 52 different genetic profiles of K. pneumoniae. Analysis of the DNA profiles indicated 45 unrelated, unique genotypes and 7 related (16 isolates from 15 patients) genotypes. Urine flow impairment emerged as an independent predictor of K. pneumoniae upper UTIs (OR 14.28, CI 2.7-75.56, P 0.002), while we did not find any association between the profile of VFs and developing upper UTIs. The prevalence of the uge gene was lower in RTx patients on everolimus when compared to isolates from patients not receiving mTOR inhibitors (33.3 % vs 82.8 % P<0.05).

Conclusions: K. pneumoniae upper UTI may be a marker of urine flow impairment. Bacterial VFs could not discriminate between upper and lower UTIs. However, immunosuppression may influence the selection of particular VFs.