AUTHOR=Jiang Qi , Ke Bi-xia , Wu De-shu , Wang Dong , Fang Liang-xing , Sun Ruan-yang , Wang Min-ge , Lei Jing-er , Shao Zheng , Liao Xiao-ping 

TITLE=Epidemiology of blaCTX-M-Positive Salmonella Typhimurium From Diarrhoeal Outpatients in Guangdong, China, 2010–2017

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.865254

DOI=10.3389/fmicb.2022.865254

ISSN=1664-302X

ABSTRACT=<p><italic>Salmonella enterica</italic> can lead to intestinal diarrhea, and the emergence and spread of cephalosporin-resistant <italic>Salmonella</italic> have brought great challenges to clinical treatment. Therefore, this study investigated the prevalence and transmission of <italic>bla</italic><sub>CTX-M</sub> genes among <italic>S.</italic> Typhimurium from diarrhoeal outpatients in Guangdong, China, from 2010 to 2017. A total of 221 <italic>bla</italic><sub>CTX-M</sub>-positive isolates were recovered from 1,263 <italic>S.</italic> Typhimurium isolates from the facal samples of diarrhoea patients in 45 general hospitals from 11 cities. The most popular CTX-M gene was <italic>bla</italic><sub>CTX-M-55</sub> (39.6%, 72/182) in the CTX-M-1 group, followed by <italic>bla</italic><sub>CTX-M-14</sub> (22.5%, 41/182) and <italic>bla</italic><sub>CTX-M-65</sub> (19.2%, 35/182) in the CTX-M-9 group. The isolates that carried <italic>bla</italic><sub>CTX-M-9G</sub> had significantly higher resistance rates to multiple antibacterials compared with <italic>bla</italic><sub>CTX-M-1G</sub> (<italic>p</italic> &lt; 0.01). Meanwhile, PFGE analysis not only showed the clonal transmission of <italic>bla</italic><sub>CTX-M-55/14/65</sub>-positve isolates of diarrhoeal outpatients’ origins from different hospitals in Guangdong province, but also the characteristic of <italic>bla</italic><sub>CTX-M-55/14/65</sub>-positve isolates’ bacterial persistence. Multilocus sequence typing (MLST) analysis indicated that these <italic>S.</italic> Typhimurium isolates possessed ST34 and ST19. Furthermore, genomic Beast phylogenomic analysis provided the evidence of a close relationship of <italic>bla</italic><sub>CTX-M</sub>-positive <italic>S.</italic> Typhimurium isolates between the outpatients and pork. Most <italic>bla</italic><sub>CTX-M-55/14/65</sub> genes were transmitted by non-typeable or IncI1/IncFII/IncHI2 plasmids with the size of ranging from ~80 to ~280 kb. Moreover, whole-genome sequencing (WGS) analysis further revealed that <italic>bla</italic><sub>CTX-M-55/14/65</sub> coexisted with other 25 types of ARGs, of which 11 ARGs were highly prevalent with the detection rates &gt;50%, and it first reported the emergence of <italic>bla</italic><sub>TEM-141</sub> in <italic>S.</italic> Typhimurium. This study underscores the importance of surveillance for <italic>bla</italic><sub>CTX-M</sub>-positive microbes in diarrhea patients.</p>