Characterisation of 16S rRNA gene, phylogenetic analysis, and multidrug resistance profiling of hospital-associated Myroides and Bacillus strains from Anambra State, Nigeria

Objective: Hospital indoor microenvironments host multidrug-resistant (MDR) opportunistic bacteria that contribute significantly to healthcare-associated infections (HAIs). This study evaluated the phenotypic multidrug resistance profiles, extrachromosomal plasmid carriage, 16S rRNA gene sequence resources, and phylogenetic topologies of two MDR opportunistic pathogens—Myroides sp. strain Awka-1 (PZ744397) and Bacillus sp. strain Awka-1 (PZ744398)—isolated from hospital environments in Awka, Anambra State, Nigeria. Results: Target MDR isolates were recovered from hospital air (Myroides sp. strain Awka-1 PZ744397) and healthcare staff attire (Bacillus sp. strain Awka-1 PZ744398). Antimicrobial susceptibility testing revealed high-level multidrug resistance, with Multidrug Resistance Index (MRI) values of 0.5 (Myroides sp. strain Awka-1) and 0.4 (Bacillus sp. strain Awka-1). Plasmid profiling demonstrated extrachromosomal plasmid carriage in both strains. Evolutionary trees constructed via Maximum Likelihood method placed Myroides sp. strain Awka-1 PZ744397 in a high-confidence clade alongside Myroides odoratimimus subsp. xuanwuensis strain M2S3B6 and Myroides odoratimimus strain WRBC, whilst Bacillus sp. strain Awka-1 PZ744398 clustered firmly within the Bacillus cereus species complex (alongside Bacillus cereus strain NOORBSRJ12 and Bacillus cereus ATCC 14579). These GenBank sequence deposits provide baseline molecular markers for tracking environmental reservoirs of MDR pathogens in regional healthcare settings.