Aim This study aimed to characterise the resistome of Acinetobacter isolates from pharmaceutical effluents and assess its association with phylogeny. Methodology In this study, Whole-genome sequences were assembled and screened for Antimicrobial Resistance (AMR) genes using CARD. Core and accessory resistomes were defined, and phylogeny was inferred using 16S rRNA analysis. Results Isolates carried 13–35 AMR genes despite shared origin. Efflux systems (AdeIJK, AdeABC) formed a conserved intrinsic core, while accessory genes, including OXA-type carbapenemases, ESBLs, aminoglycoside- and sulfonamide-resistance genes, and qacEΔ1, were variably distributed. Resistome patterns did not strictly follow phylogeny. Interpretation Pharmaceutical effluents select for a conserved efflux-based resistance backbone while enabling dynamic acquisition of accessory genes via Horizontal Gene Transfer, highlighting the role of environmental pressure in multidrug resistance evolution.
Iyer et al. (2026) studied this question.