Analysis of carbapenem-resistant Acinetobacter baumannii carbapenemase gene distribution and biofilm formation.

OBJECTIVE: In recent years, Acinetobacter baumannii has been appearing in hospitals with high drug resistance and strong vitality, which brings many difficulties to clinical treatment. In this study, 255 strains of A. baumannii were isolated from Youjiang Medical University for Nationalities Affiliated Hospital clinical samples and found to be highly resistant to carbapenems. The drug resistance, biofilm-forming ability, and carbapenase gene distribution of 145 carbapenem-resistant A. baumannii (CRAB) strains were analyzed statistically.

METHODS: The clinically isolated strains were detected using Vitek mass spectrometry and Vitek2-compact for bacterial identification and susceptibility testing, respectively. The biofilms of clinical isolates were quantitatively detected by microplate crystal violet staining, and qualitatively observed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). And the common carbapenemase genes were detected by polymerase chain reaction (PCR).

RESULTS: The 255 clinical isolates from the Youjiang District of western Guangxi Province had a high resistance rate to carbapenems antibiotics. The main specimens were from the intensive care unit (49%), and the most important specimens were sputum specimens (80%). All 145 strains of CRAB produced different degrees of biofilm, and six carbapenenase genes were detected. We found that there were significant differences in biofilm formation between resistant and sensitive strains of tobramycin, levofloxacin, ciprofloxacin, tigecycline, and doxycycline ( P <0.05). The distribution of blaOXA-23 and blaOXA51 genes was significantly different from CRAB biofilm formation ( P <0.05). In addition, AmpC , blaOXA-23 , blaOXA-51 , and TEM genes were more distributed in antibiotic-resistant strains.

CONCLUSION: The clinical strains have a high resistance rate to carbapenems, and the CRAB with blaOXA-51 and blaOXA-23 genes has a high resistance to antibiotics and a strong biofilm.