The Correlation of Efflux Pumps and Porin Proteins with Carbapenem Resistance in Clinical Isolated Acinetobacter baumannii from Sina Hospital-Tabriz

Abstract

Carbapenem resistant Acinetobacter baumannii (CRAB) is increasingly recognized as an important nosocomial pathogen, especially in the intensive care units (ICUs), and has made difficult the treatment of infections. Enzymatic degradation by oxacillinase and metallo β-lactamase is the most common mechanism of resistance to carbapenem, but changes in the expression of efflux pumps and porin proteins can also contribute to this resistance. In this study, different mechanisms of resistance to carbapenem were investigated in A. baumannii clinical isolates. Methods: 112 A. baumannii isolates were collected from clinical specimens of patients admitted to Sina hospital in Tabriz. After agar disk diffusion and MIC determination, PCR method was performed to determine the frequency of oxacillinase and metallo β-lactamase genes and Real-time PCR was performed to determine the expression of adeB, adeJ and carO, omp 33-36, oprD genes. Results: All A. baumannii isolates were resistant to carbapenems and had blaOXA-51 gene. 82.1% of them carried blaOXA-23 gene and 36.6% blaOXA-24 gene. The prevalence of metallo β-lactamase genes was 10.7% including 4.5% blaIMP and 6.2% blaNDM. Overexpression of efflux proteins adeB, adeJ was observed in 66% and 42.8%, respectively, and low expression of porins carO, omp 33-36, oprD was observed in 77.7%, 66.6% and 74% of isolates, respectively.