Genomic Insights into Drug Resistance and Virulence Determinants in Rare Pyomelanin-producing Clinical Isolates of Acinetobacter Baumannii

Overview

Journal Eur J Clin Microbiol Infect Dis

Publisher Springer

Specialties Infectious Diseases
Microbiology

Date 2024 Dec 19

PMID 39699780

Authors

Lipsa Panda

Krishnapriya Gk

Ajit Ramesh Sawant

Santosh Kumar Singh

Minakshi Gupta

Sheela Devi C

P Shashikala

K Prashanth

Affiliations

Soon will be listed here.

Abstract

Purpose: Clinical isolates of multi-drug resistant Acinetobacter baumannii are a major cause of nosocomial infections, often attributed to the highly adaptable genome that helps it to thrive under environmental selection pressure. Here, we aim to provide genotypic-based surveys and comparative whole genome sequencing (WGS) analysis to explore the genomics of the rare pyomelanin-forming clinical isolates of A. baumannii from India.

Methods: A total of 54 clinical isolates of A. baumannii obtained from two tertiary care hospitals were genotyped using repetitive sequence-based PCR (REP-PCR) for elucidating their molecular epidemiology, followed by their resistance profiling through the determination of minimum inhibitory concentration using the micro broth dilution method. The isolates' virulence and antibiotic-resistant determinants were detected by PCR screening, followed by biofilm quantification. Pyomelanin pigment produced by A. baumannii isolates was isolated and chemically characterized. Finally, WGS of three pigment-producing and one non-producing A. baumannii strains was performed to explore the factors contributing to their variability.

Results: REP-PCR genotyping identified around 8 clusters, with all isolates being multidrug-resistant (MDR). Pyomelanin-producing isolates were strong biofilm formers, characterized by the concurrent presence of 'pgaB, BfmR, BfmS, ompA, and cusE' biofilm-related genes. These pigmented strains belonged to ST2 and co-harbored bla, bla, aph (3')-VIa, armA, aph (6)-Id, tet(B) and msr(E) genes. Thirteen common IS elements and biosynthetic gene clusters of arylpolyene, NI-siderophore, and NRP-metallophore were identified. Notably, genomic islands containing aminoglycoside 3'-phosphotransferase, oxidative stress, two-component response regulators, efflux pump-related, toxin-antitoxin protein, and virulence-related genes were also mapped by WGS.

Conclusion: The pyomelanin-forming isolates were MDR and virulent. The elucidation of WGS analysis provided critical insights for understanding the epidemiology, virulome, and mobilome of rare pigment-producing A. baumannii strains.

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