Multiple drug resistant carbapenemases producing Acinetobacter baumannii isolates harbours multiple R-plasmids

Area of Science:

• Microbiology
• Molecular Biology
• Clinical Infectious Diseases

Background:

• Acinetobacter baumannii is a significant nosocomial pathogen known for rapid antimicrobial resistance development.
• Multidrug resistance (MDR) in A. baumannii complicates treatment options.
• This study investigates the role of plasmids in A. baumannii resistance.

Purpose of the Study:

• To identify resistant plasmids (R-plasmids) in clinical A. baumannii isolates.
• To detect common beta-lactamase encoding genes on these plasmids.
• To confirm plasmid-mediated antibiotic resistance.

Main Methods:

• Plasmid DNA isolation and PCR for resistance genes (blaOXA-23, blaOXA-51, blaOXA-58, blaIMP-1).
• Plasmid curing using ethidium bromide and acridine orange.
• Antibiotic resistance profiling before and after plasmid curing.

Main Results:

• Multiple plasmids were detected in 55 clinical A. baumannii isolates.
• blaOXA-51 (78%) and blaOXA-23 (42%) were frequently found on plasmids.
• 36% of isolates carried the blaIMP-1 gene on plasmids.
• Plasmid curing resulted in increased susceptibility to multiple antibiotic classes.

Conclusions:

• Plasmid-mediated resistance mechanisms are prevalent in MDR A. baumannii.
• Multiple plasmids contribute to the antibiotic resistance profile.
• Preventive measures are crucial to curb the spread of plasmid-borne resistance determinants in healthcare settings.