Sayem Mohammad, Rafi Mahbub Arefin, Mishu Israt Dilruba, Mahmud Zimam
Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, 1000, Bangladesh.
Department of Microbiology, University of Dhaka, Dhaka, 1000, Bangladesh.
Sci Rep. 2025 Jul 2;15(1):22915. doi: 10.1038/s41598-025-06655-w.
Hospital wastewater represents a significant reservoir for antimicrobial-resistant bacteria, including multidrug-resistant (MDR) Bacillus cereus, a pathogen of growing concern due to its potential impact on public health and environmental safety. This study characterizes the genomic features, antimicrobial resistance (AMR) mechanisms, and virulence potential of Bacillus cereus MBC, isolated from hospital wastewater in Dhaka, Bangladesh. Using whole-genome sequencing (WGS) and advanced bioinformatics, we analyzed the isolate's taxonomy, phylogenetics, functional annotation, and biosynthetic potential. The genome, spanning 5.6 Mb with a GC content of 34.84%, contained 5,881 protein-coding sequences, including 1,424 hypothetical proteins, and 28 genes associated with AMR. Phylogenetic analysis revealed a close genetic relationship with Bacillus cereus ATCC 14579, sharing virulence factors such as hemolysin BL (HBL), non-hemolytic enterotoxin (NHE), and cytotoxin K (CytK), all contributing to its pathogenicity. The ability to form biofilms further enhances the strain's persistence and resistance in hospital environments. AMR profiling identified genes conferring resistance to beta-lactams (e.g., BcI, BcII, BcIII), tetracyclines (tetB(P)), glycopeptides (vanY), and fosfomycin, highlighting the bacterium's capacity to resist a wide array of antibiotics. Functional annotation revealed metabolic pathways involved in iron acquisition and the biosynthesis of siderophores such as petrobactin and bacillibactin, reinforcing the bacterium's adaptability in nutrient-limited environments. Mobile genetic elements, including prophages, CRISPR-Cas systems, and transposable elements, suggest significant horizontal gene transfer (HGT), enhancing genetic plasticity and resistance spread. Pangenomic analysis, involving 125 B. cereus strains, revealed a high degree of genetic diversity and close relationships with strains from clinical, food, and agricultural environments, emphasizing the overlap between clinical and environmental reservoirs of resistance. The strain's isolation from hospital wastewater underscores the complex interplay between environmental contaminants and bacterial evolution, which fosters MDR traits. Our findings underscore the urgent need for enhanced genomic surveillance and wastewater management strategies to mitigate the spread of MDR B. cereus and AMR genes in hospital environments.
医院废水是耐药菌的重要储存库，包括多重耐药（MDR）蜡样芽孢杆菌，由于其对公众健康和环境安全的潜在影响，该病原体日益受到关注。本研究对从孟加拉国达卡医院废水中分离出的蜡样芽孢杆菌MBC的基因组特征、抗菌耐药性（AMR）机制和毒力潜力进行了表征。通过全基因组测序（WGS）和先进的生物信息学方法，我们分析了该分离株的分类学、系统发育学、功能注释和生物合成潜力。该基因组跨度为5.6 Mb，GC含量为34.84%，包含5881个蛋白质编码序列，其中包括1424个假定蛋白质，以及28个与AMR相关的基因。系统发育分析显示，它与蜡样芽孢杆菌ATCC 14579有密切的遗传关系，共享溶血素BL（HBL）、非溶血肠毒素（NHE）和细胞毒素K（CytK）等毒力因子，这些都有助于其致病性。形成生物膜的能力进一步增强了该菌株在医院环境中的持久性和耐药性。AMR分析确定了赋予对β-内酰胺类（如BcI、BcII、BcIII）、四环素类（tetB(P)）、糖肽类（vanY）和磷霉素耐药的基因，突出了该细菌对多种抗生素的耐药能力。功能注释揭示了参与铁获取以及铁载体（如petrobactin和bacillibactin）生物合成的代谢途径，增强了该细菌在营养有限环境中的适应性。包括前噬菌体、CRISPR-Cas系统和转座元件在内的移动遗传元件表明存在显著的水平基因转移（HGT），增强了遗传可塑性和耐药性传播。涉及125株蜡样芽孢杆菌的泛基因组分析显示，其遗传多样性程度高，且与临床、食品和农业环境中的菌株关系密切，强调了临床和环境耐药菌库之间的重叠。从医院废水中分离出该菌株突出了环境污染物与细菌进化之间的复杂相互作用，这种相互作用促进了MDR特性的形成。我们的研究结果强调了迫切需要加强基因组监测和废水管理策略，以减轻MDR蜡样芽孢杆菌和AMR基因在医院环境中的传播。
