AUTHOR=Zhang Shaqiu , Shu Yanxi , Yang Zhechen , Zhong Zhijun , Wang Mingshu , Jia Renyong , Chen Shun , Liu Mafeng , Zhu Dekang , Zhao Xinxin , Wu Ying , Yang Qiao , Huang Juan , Ou Xumin , Sun Di , Tian Bin , Wu Zhen , He Yu , Cheng Anchun 

TITLE=Decoding the enigma: unveiling the transmission characteristics of waterfowl-associated blaNDM-5-positive Escherichia coli in select regions of China

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 15 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1501594

DOI=10.3389/fmicb.2024.1501594

ISSN=1664-302X

ABSTRACT=Escherichia coli (E. coli) serves as a critical indicator microorganism for assessing the prevalence and dissemination of antibiotic resistance, notably harboring various antibiotic-resistant genes (ARGs). Among these, the emergence of the blaNDM gene represents a significant threat to public health, especially since carbapenem antibiotics are vital for treating severe infections caused by Gram-negative bacteria. This study aimed to characterize the antibiotic resistance features of blaNDM-5-positive E. coli strains isolated from waterfowl in several regions of China and elucidate the dissemination patterns of the blaNDM-5 gene. We successfully isolated 103 blaNDM-5-positive E. coli strains from 431 intestinal fecal samples obtained from waterfowl across five provincial-level units in China, with all strains exhibiting multidrug resistance (MDR). Notably, the blaNDM-5 gene was identified on plasmids, which facilitate efficient and stable horizontal gene transfer (HGT). Our adaptability assays indicated that while the blaNDM-5-positive plasmid imposed a fitness cost on the host bacteria, the NDM-5 protein was successfully induced and purified, exhibiting significant enzymatic activity. One strain, designated DY51, exhibited a minimum inhibitory concentration (MIC) for imipenem of 4 mg/L, which escalated to 512 mg/L following exposure to increasing imipenem doses. This altered strain demonstrated stable resistance to imipenem alongside improved adaptability, correlating with elevated relative expression levels of the blaNDM-5 and overexpression of efflux pumps. Collectively, this study highlights the horizontal dissemination of the blaNDM-5 plasmid among E. coli strains, confirms the associated fitness costs, and provides insights into the mechanisms underlying the stable increase in antibiotic resistance to imipenem. These findings offer a theoretical framework for understanding the dissemination dynamics of blaNDM-5 in E. coli, which is essential for developing effective strategies to combat carbapenem antibiotic resistance.