Molecular epidemiology and carbapenem resistance of isolated from patients with burns.

OBJECTIVE

The aim of this study was to investigate the molecular epidemiology and carbapenem resistance mechanisms of isolated from patients with burns in Azerbaijan, Iran.

METHOD

was isolated from 38 patients with burns. Disk diffusion and agar dilution methods were used to determine antibiotic susceptibility patterns. The overproduction of AmpC β-lactamase and efflux pumps were detected by phenotypic methods. The presence of carbapenemase-encoding genes was detected by multiplex polymerase chain reaction (PCR). Expression of the gene and MexAB efflux pumps were also evaluated with real-time PCR. Random amplified polymorphic DNA typing (RAPD-PCR) was used for genotyping of carbapenem-resistant (CRPA).

RESULTS

Minimum inhibitory concentration (MIC) assays demonstrated high levels of resistance to all classes of antibiotics except colistin and polymyxin B. The initial screening by carbapenem disks indicated 24 isolates (63.15%) as CRPA. Different mechanisms of carbapenem resistance were observed, including carbapenemase production (8.4%), overexpression of AmpC (25%) and decreased expression of (75%). The overexpression of MexAB efflux pumps was detected in 19 (79.1%) isolates by phenotypic assay or real-time PCR. The resistance to carbapenem was multifactorial in most cases (58.3%). The RAPD genotyping revealed different patterns with nine clusters.

CONCLUSION

According to our results, the prevalence of CRPA is at an alarming level. Our results did not demonstrate an epidemic clone. The most common mechanism of carbapenem resistance was decreased expression of . Therefore, we suggest a reconsideration in the management of CRPA infections of patients in our burn care hospital in Azerbaijan, Iran.