Prevalence of extended-spectrum β-lactamases, AmpC, and carbapenemases in Proteus mirabilis clinical isolates

Background: Proteus mirabilis is an opportunistic pathogen, causing a variety of community-acquired and nosocomial illnesses. It poses a potential threat to patients via the production of beta-lactamases, which decrease the efficacy of antimicrobial treatment and impair the management of its pathogenicity. Hence, this study was established to determine the prevalence of extended-spectrum beta-lactamases (ESBLs), AmpC, and carbapenemases of P. mirabilis isolated from various clinical specimens. Results: Proteus mirabilis was identified in 20.7% (58/280) of specimens. ESBL producers were present at a rate of 51.7% (30/58). All AmpC-positive isolates (n = 20) produced ESBLs as well, so 66.7% of ESBL-producing isolates coproduced AmpC enzymes. The modified Hodge test confirmed carbapenemase production in six out of seven imipenem nonsusceptible isolates. Of these, only two (5.7%) isolates were also ESBL-and AmpC-positive. Antibiotic resistance reached the highest level for cotrimoxazole (62.1%, n = 36/58 isolates) and the lowest for imipenem (12.1%, n = 7/58 isolates). The levels of multidrug-resistant (MDR) was 41.4% among the tested isolates. The bla(SHV) (83.3%), bla(AmpC) (80%), and bla(VIM-1) (50%) were the most detected genes in phenotypically confirmed ESBL-, AmpC-, and carbapenemase-producing isolates, respectively. Besides, more than a half of the tested P. mirabilis strains (53%) coproduced ESBLs and AmpC. Moreover, two isolates coproduced ESBLs and AmpC together with carbapenemases. Furthermore, dendrogram analysis showed great genetic divergence based on the 21 different enterobacterial repetitive intergenic consensus (ERIC) patterns (P1-P21) through the 34 beta-lactamase producers. ERIC analysis distinguished clonal similarities between isolates 21 and 22 in P2 and 9 and 10 in P4, which were isolated from the same clinical source and possessed similar patterns of beta-lactamase-encoding genes. Conclusion: Hence, there is an urgent need to monitor hospitalized patients and improve healthcare in order to reduce the incidence of infection and outbreaks of infection with antibiotic-resistant Proteus.

Automated summary

This study aimed to determine the prevalence of β-lactamases, AmpC, and carbapenemases in Proteus mirabilis isolated from clinical specimens. The results showed a high level of antibiotic resistance, with 41.4% of isolates being multidrug-resistant. The most detected genes were bla(SHV), bla(AmpC), and bla(VIM-1). Additionally, some strains produced both ESBL and AmpC, and there were even strains that co-produced ESBL, AmpC, and carbapenemases. Moreover, genetic analysis based on ERIC patterns revealed high genetic diversity.