First report of blaOXA-24 carbapenemase gene, armA methyltransferase and aac(6')-Ib-cr among multidrug-resistant clinical isolates of Proteus mirabilis in Algeria.

OBJECTIVE: Carbapenemase-producing, or carbapenem-resistant, Enterobacteriaceae are an emerging threat to human and animal health because they are resistant to many of the last-line antimicrobials available for treatment of infection. The aim of this study was to analyse the antimicrobial resistance patterns and their encoding genes of Proteus mirabilis isolated in Constantine, Algeria. METHODS: A total of 108 Proteus, Morganella and Providencia (PMP) strains were isolated from a large variety of clinical specimens at University Hospital of Constantine in Algeria. Isolates were identified using the API 20E system and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Diagnostic accuracy was determined by independent comparison of each method to phylogenetic analysis based on 16S rRNA gene sequencing. Antimicrobial susceptibility was determined by the standard disk diffusion and Etest methods. The presence of antimicrobial resistance genes was screened for by PCR amplification and sequencing. RESULTS: A total of 72 PMP strains were multidrug-resistant (MDR). Among them, one P. mirabilis isolate was resistant to imipenem with a minimum inhibitory concentration (MIC) of ≥12µg/mL. PCR and sequencing showed the presence of various antimicrobial resistance genes, including blaCTX-M-15, blaTEM-1, blaTEM-2, blaPER-1, blaSHV-11, aadA1, aadA2, armA, aac(6')-Ib, aac(6')-Ib-cr, aac(3)-Ia and ant(2″)-I, forming different resistance profiles. Moreover, the blaOXA-24 gene was detected in the imipenem-resistant P. mirabilis strain. CONCLUSION: In this study, a MDR P. mirabilis isolate harbouring the blaOXA-24, armA 16S rRNA methylase and aac(6)-Ib-cr genes was found for the first time in Algeria.