Characterization of blaNDM–5-carrying plasmids in two clinical Salmonella isolates from Jiaxing city, China
Ping Li, Yongjuan Yuan, Yong Yan, Miaomiao Jia, Lei Gao, Xuejuan Liu, Yangming Sun, Guoying Zhu, Zhongwen Chen
Abstract
Introduction Salmonella is an important cause of foodborne diarrheal diseases worldwide. The emergence of bla NDM -positive carbapenem-resistant Salmonella enterica isolates in recent years poses a huge public health challenge. Methods In this study, two clinical S. enterica isolates carrying bla NDM–5 : a serotype 4,[5],12:i:- strain (2023JX045) and a serovar Stanley strain (2024–406) were analyzed using antimicrobial susceptibility testing and whole genome sequencing. Results Both isolates were multidrug resistant, with insusceptibility to ampicillin, ampicillin/sulbactam, amoxicillin/clavulanic acid, cefuroxime, ceftiofur, cefazolin, cefoxitin, cefotaxime, ceftazidime, cefepime, ceftazidime/avibactam, meropenem, imipenem, ertapenem, tetracycline, gentamicin, trimethoprim/sulfamethoxazole, florfenicol, chloramphenicol, ciprofloxacin, colistin, and polymixin B. The bla NDM–5 -carrying plasmids in 2023JX045 and 2024–406 were named p23045-NDM5 and p2024406-NDM5, respectively, with both belonging to the incompatibility (Inc)HI2/IncHI2A group and sequence type ST3. In 2023JX045, bla NDM–5 was flanked by two same-oriented copies of IS 26 elements (IS 26-dsbC-trpF - ble MBL - bla NDM–5 -IS 5 -ΔIS 3000 -ΔIS Kox3-umuC-umuD -IS 26 ). In 2024–406, p2024406-NDM5 was found to carry two copies of bla NDM–5 , possibly resulting from duplication of IS 26 - dsbC-trpF - ble MBL - bla NDM–5 -IS5-ΔISAba125-ΔIS3000-ΔISKox3-umuC-umuD-IS26 and interrupted by mobile element IS 1 at the upstream region of ΔIS3000. Discussion This is the first report to describe the presence of two bla NDM–5 copies on an IncHI2/IncHI2A plasmid carried by serovar Stanley, as well as the dissemination of bla NDM–5 in Salmonella in Jiaxing City, China. IS26-flanked composite transposons appeared to play an important role in the formation of this region. The dissemination of blaNDM in Salmonella isolates and the complexity of the bla NDM–5 region highlight the urgent need to monitor carbapenem-resistant S. enterica .