Characterization of antimicrobial resistance among Proteus mirabilis isolates from catheter-associated urinary tract infections and non-catheter-associated urinary tract infections in Egypt

Abstract

Background

Recent worldwide reports of increased numbers of multidrug-resistant (MDR) Proteus mirabilis (P. mirabilis) isolates, particularly those producing extended-spectrum β-lactamases (ESBLs), are alarming. P. mirabilis is a common causative agent of complicated urinary tract infections (UTIs), particularly in patients with long-term urinary catheterization. This study aimed to assess the prevalence, antibiotic resistance patterns, and determinants of P. mirabilis among catheter-associated UTIs (CAUTI) and non-catheter-associated UTIs (non-CAUTI).

Methods

One hundred and three Proteus strains isolated from 613 UTI patients in Minia, Egypt, were examined for antibiotic resistance patterns, ESBL production, and sulphonamide resistance phenotypically. Class 1 and 2 integrons, ESBL, and sul resistance genes were detected by Polymerase chain reaction (PCR), followed by molecular typing of ESBL-producing isolates from catheterized UTI patients using ERIC-PCR.

Results

Proteus isolates were detected in 20% of the UTIs, with a higher rate among inpatients (27.3%) compared to outpatients (10.6%). Proteus was more significantly isolated from catheterized UTI patients (28.2%, 55/195) than from non-catheterized patients (14.9%, 48/321). Of the 103 Proteus isolates, 99 (96.1%) were identified as P. mirabilis. High resistance was observed against trimethoprim/sulfamethoxazole (SXT) (80.6%), amoxicillin-clavulanic (AMC) (57.3%), ceftazidime (55.3%), and imipenem (46.6%) antibiotics. Significantly higher resistance rates were observed among Proteus isolates from inpatients and catheterized patients. Of the 103 Proteus strains, 81 (78.6%) were MDR, with 70.9% of the isolates from catheterized patients. About 74.6% of the isolates from inpatients were MDR. Sul genes were detected in 77 isolates (74.7%). The frequency of ESBL-producing Proteus isolates was 37.9% which was significantly higher in catheterized patients with increasing dissemination of bla_TEM genes and bla_CTX-M genes. Int1 and Int2 genes were detected in 92.2% and 68.9% of isolates, respectively. ERIC-PCR revealed moderate similarity (65%) between ESBL-producing Proteus isolates from catheterized patients.

Conclusion

The high frequency of MDR P. mirabilis strains isolated from UTIs in Egypt, particularly among catheterized patients, is a major concern, especially with disseminating class 1 and 2 integrons among isolates. The study also highlights the decreased susceptibility to sulphonamides, 3rd generation cephalosporins, and imipenem, commonly used to treat UTIs. Increased dissemination of ESBL-producing Proteus isolates among CAUTIs complicates their treatments. This important pathogen deserves more attention in the future for a better understanding of resistance mechanisms and the dissemination potential of resistant strains.