Zhong Yang, Teo Jocelyn Qi-Min, Guo Siyao, Schlundt Joergen, Kwa Andrea Lay-Hoon, Ong Rick Twee-Hee
Department of Clinical Translational Research, Singapore General Hospital, Singapore, Singapore; Department of Pharmacy, Singapore General Hospital, Singapore, Singapore; School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore; SingHealth Duke-NUS Medicine Academic Clinical Programme, Singapore, Singapore.
Department of Pharmacy, Singapore General Hospital, Singapore, Singapore.
Sci Total Environ. 2025 May 25;978:179353. doi: 10.1016/j.scitotenv.2025.179353. Epub 2025 Apr 16.
Extended-spectrum β-lactamase producing (ESBL) bacteria from aquatic environments can pose potential threats to public health due to their capability of spreading antimicrobial resistance (AMR) genes through mobile genetic elements (MGEs), such as plasmids, insertion sequences (ISs), transposons, and integrons. Currently, there is no policy for routine monitoring of AMR genes in aquatic environments and their roles in transmission are therefore unknown. Previous metagenomic and PCR-based culture-independent approaches are limited in recovering AMR resistant aquatic bacteria isolates and the data resolution generated are not able to provide detailed genetic comparison with known human pathogens particularly for determining genetic islands harbouring AMR genes. To address these gaps, we thus investigated the genetic profiles of ESBL-producing gram-negative aquatic bacteria found from water body sites within Singapore, examining the AMR genes carried and their associated MGEs. In total, 16 ESBL-producing gram-negative bacteria were identified, of which 8 were Escherichia coli, 3 Klebsiella pneumoniae, and 5 Aeromonas spp. Whole genome sequencing (WGS) analysis revealed the presence of 12 distinct classes of AMR genes, including 16 distinct variants of β-lactamase, of which bla was the dominant beta-lactamase genotype in all 11 Enterobacterales. The AMR genetic islands in the aquatic bacteria were also found to share similar genetic structures similar to those of circulating ESBL bacteria causing human infections. These findings underscore the potential role of aquatic ESBL bacteria as AMR reservoirs for human pathogens, suggesting that aquatic bacteria may facilitate the hidden transmission of AMR mediated by MGEs through horizontal gene transfer across different sources and species, highlighting the importance of integrating environmental AMR monitoring into local surveillance strategies.
来自水生环境的产超广谱β-内酰胺酶（ESBL）细菌可能对公众健康构成潜在威胁，因为它们能够通过移动遗传元件（MGEs）传播抗菌药物耐药性（AMR）基因，这些元件包括质粒、插入序列（ISs）、转座子和整合子。目前，尚无针对水生环境中AMR基因进行常规监测的政策，因此其在传播中的作用尚不清楚。以往基于宏基因组学和PCR的非培养方法在分离AMR耐药水生细菌方面存在局限性，所产生的数据分辨率无法与已知人类病原体进行详细的基因比较，特别是在确定携带AMR基因的基因岛方面。为了填补这些空白，我们调查了在新加坡水体部位发现的产ESBL革兰氏阴性水生细菌的基因图谱，检测了所携带的AMR基因及其相关的MGEs。总共鉴定出16株产ESBL革兰氏阴性细菌，其中8株为大肠杆菌，3株为肺炎克雷伯菌，5株为气单胞菌属。全基因组测序（WGS）分析显示存在12种不同类别的AMR基因，包括16种不同变体的β-内酰胺酶，其中bla是所有11株肠杆菌科细菌中占主导地位的β-内酰胺酶基因型。还发现水生细菌中的AMR基因岛与引起人类感染的循环ESBL细菌具有相似的遗传结构。这些发现强调了水生ESBL细菌作为人类病原体AMR储存库的潜在作用，表明水生细菌可能促进MGEs介导的AMR通过水平基因转移在不同来源和物种之间的隐性传播，突出了将环境AMR监测纳入当地监测策略的重要性。
