Antimicrobial Resistant Determination and Prokaryotic Expression of smpA Gene of Acinetobacter baumannii Isolated from Admitted Patients

Background: Acinetobacter baumannii is a leading cause of worldwide nosocomial infections. As many infections are caused by multidrug-resistant strains, the antibiotic-therapy of them has become greatly difficult. Objectives: The present study was aimed to evaluate the antimicrobial susceptibility of A. baumannii as well as cloning and expression of A. baumannii-smpA gene isolated from infectious patients. Methods: Sixty-seven samples were collected from different clinical infections wards especially intensive-care units (ICU). The A. baumannii was identified according to bacteriological standard method. The antibiotic resistance patterns of the isolates were analyzed by the disk diffusion method. The smpA was amplified by Polymerase chain reaction (PCR) following cloning and sub-cloning in T-vector and expression vector, respectively. Colony-PCR, double-digestion and DNA sequencing confirmed that smpA was cloned into the vectors. The expression of rSmpA in IPTG-induced E. coli-DE3 was examined by Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Results: Thirty out of 67 isolates (44.78%) were positive for A. baumannii among which, more than 83% were resistance to all generation of Cephalosporins and the least resistance (10%) was observed for Colistin. The smpA-amplicon was 417 bp. Colony-PCR, double-digestion and sequencing showed that the target gene was inserted into the pTZ57RT and pET32a (+), successfully. Obtaining of a similar to 15 KDa band in SDS-PAGE showed the recombinant pET32a/smpA was highly expressed. Conclusions: These results indicated that high resistance to antibiotics among isolates and high conserved of smpA gene at sequence level among A. baumannii strains, therefore it can be used as an antigenic target for generation vaccine against multi drug resistant (MDR) A. baumannii infections.