Whole genome sequencing and genomic characterization of the extensively drug-resistant Acinetobacter baumannii recovered from clinical samples in Lahore, Pakistan.

BACKGROUND

Extensively drug-resistant (XDR) Acinetobacter baumannii has turned into a significant nosocomial pathogen often resistant to all available classes of antibiotics. It has been identified as a key public health issue due to its capacity to get resistance determinants, virulence genes, and mobile genetic elements. This study hypothesized that the XDR A. baumannii isolated in Pakistan would harbor some of the key genomic determinants of the resistance and pathogenicity.

METHODOLOGY: A total of 11 A. baumannii were obtained from the patient samples and were identified using microbiological, biochemical, and genomic analysis. The sensitivity to antibiotics was determined by Kirby-Bauer disc diffusion assay. While the whole genome sequencing (WGS) was performed for the single XDR Acinetobacter isolate TAB-4 and its in-silico genome analysis on resistant genes, virulence factors, plasmids, mobile genetic elements, prophages, CRISPR-Cas and biosynthetic gene clusters was conducted.

RESULTS

The isolated strains were 10 multidrug resistant (MDR) and one (TAB-4) was XDR Acinetobacter strain. The AST showed resistance to nearly all classes of antibiotics, and with limited susceptibility to tetracyclines and aminoglycosides. The genome of TAB-4 strain comprised of 3.94 Mb, 120 contigs, and a GC content of 39.14%. The major resistant determinants found were blaOXA-23, blaOXA-69, blaNDM-1, blaADC-25, aminoglycoside modifying enzymes, and efflux pumps (adeABC, adeFGH, adeIJK). Virulence-associated genes (ompA, bap, csuA/B-E, plc) were identified along with five prophage regions, multiple CRISPR arrays, and a betalactone biosynthetic gene cluster.

CONCLUSION

This study to the best of our knowledge reports the first detailed WGS-based characterization of an XDR A. baumannii from Lahore, Pakistan. These genomic findings offer significant insights into the resistance and virulence factors underlying this challenging clinical issue. Hence, there is an urgent need to find new or alternative treatment methods against high-risk pathogens like XDR A. baumannii.