AUTHOR=Lu Xin , Zeng Mei , Zhang Ning , Wang Mengyu , Gu Baoke , Li Jiaqi , Jin Huiming , Xiao Wenjia , Li Zhe , Zhao Hongqun , Zhou Haijian , Li Zhenpeng , Xu Jialiang , Xu Xuebin , Kan Biao 

TITLE=Prevalence of 16S rRNA Methylation Enzyme Gene armA in Salmonella From Outpatients and Food

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.663210

DOI=10.3389/fmicb.2021.663210

ISSN=1664-302X

ABSTRACT=<p><italic>Salmonella</italic> is the primary cause of community-acquired foodborne infections, so its resistance to antimicrobials, such as aminoglycosides, is a public health issue. Of concern, aminoglycoside resistance in <italic>Salmonella</italic> is increasing rapidly. Here, we performed a retrospective study evaluating the prevalence of <italic>Salmonella</italic> harboring <italic>armA</italic>-mediated aminoglycoside resistance in community-acquired infections and in food or environmental sources. The prevalence rates of <italic>armA</italic>-harboring <italic>Salmonella</italic> strains were 1.1/1,000 (13/12,095) and 8.7/1,000 (32/3,687) in outpatient and food/environmental isolates, respectively. All the <italic>armA</italic>-harboring <italic>Salmonella</italic> strains were resistant to multiple drugs, including fluoroquinolone and/or extended-spectrum cephalosporins, and most (34/45) belonged to serovar Indiana. The <italic>armA</italic> gene of these strains were all carried on plasmids, which spanned five replicon types with IncHI2 being the dominant plasmid type. All the <italic>armA</italic>-carrying plasmids were transferable into <italic>Escherichia coli</italic> and <italic>Acinetobacter baumannii</italic> recipients. The conjugation experiment results revealed that the <italic>armA</italic>-harboring <italic>S</italic>. Indiana strains had a relatively higher ability to acquire <italic>armA</italic>-carrying plasmids. The low similarity of their pulsed field gel electrophoresis patterns indicates that the <italic>armA</italic>-harboring <italic>Salmonella</italic> strains were unlikely to have originated from a single epidemic clone, suggesting broad <italic>armA</italic> spread. Furthermore, the genetic backgrounds of <italic>armA</italic>-harboring <italic>Salmonella</italic> strains isolated from outpatients exhibited higher similarity to those isolated from poultry than to those isolated from swine, suggesting that poultry consumption maybe an infection source. These findings highlight an urgent need to monitor the prevalence and transmission of <italic>armA</italic>-harboring <italic>Salmonella</italic>, especially <italic>S.</italic> Indiana, to better understand the potential public health threat and prevent the further spread of these strains.</p>