Carbapenem-resistant Acinetobacter baumannii: prevalence, phenotypic and genotypic analysis in cases of ventilator associated pneumonia from a teaching hospital in Delhi, India

Abstract

Background and objectives

The high prevalence of multi drug resistant and carbapenam resistant Acinetobacter baumannii(CRAB)is a serious concern for patient management. The most common mechanism of carbapenamresistance is the presence of different types of carbapenamaseenzymes. The type of carbapenamase present affects the optimization of treatment. In this study, we aimed to investigate the prevalence of carbapenem resistance and characterize the genetic mechanisms associated with antimicrobial resistance in Acinetobacter baumannii isolates.

Materials and methods

All clinical isolates of CRAB from ventilator associated pneumonia were included in this study. Clinical, phenotypic, and genotypic data were collected, including clinical details, identification, antimicrobial susceptibility testing, phenotypic detection of carbapenemase activity, biofilm formation assay, and molecular identification of carbapenemase genes like blaOXA-23,blaNDM-1,blaVIM-1 and AmpC.

Result

The blaOXA-23-like gene was detected in 97 % (97/100) of CRAB isolates followed by AmpC (21/100,21 %), blaNDM-1(10/100,10 %) and blaVIM-1 in 6 % (6/100) of isolates. The mortality rate among MBL-positive patients was found to be 67 % (65/97). Furthermore, all Acinetobacter baumannii isolates exhibited biofilm-forming capacity, with varying degrees of biofilm production.

Conclusion

There is high prevalence of carbapenamase enzymes in CRAB isolates. The high detection of blaOXA-23-like, AmpC, blaNDM-1, and blaVIM-1AmpC underscores the urgency to enforce infection control measures and optimize antimicrobial stewardship practices to prevent cross transmission of the organism. Further presence of biofilm formation in almost all the isolates reiterates the need for innovative strategies to combat persistent infections by this organism.