Prevalence and Characteristics of Plasmid-Mediated Fosfomycin Resistance Gene among Enteritidis Isolates from Retail Chickens and Children with Gastroenteritis in China.

A total of 265 Enteritidis isolates collected from retail markets and children's hospitals in Shanghai were used to investigate the prevalence and molecular epidemiology of plasmid-mediated fosfomycin resistance genes. Nine of the isolates-7 from the 146 (4.79%) retail chicken-related samples and 2 from the 119 (1.68%) samples from clinical children-were fosfomycin-resistant (Fos). The gene was detected in all of the nine Fos isolates, which were located on Inc F-type (8/9, 88.9%) and unknown-type (1/9, 11.1%) transferable plasmids. In total, five plasmid types, namely Inc HI2 (1/9, 11.1%), Inc I1 (3/9, 33.3%), Inc X (8/9, 88.9%), Inc FIIs (9/9, 100%), and Inc FIB (9/9, 100%), were detected in these Fos isolates, which possessed five S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) profiles. The extended-spectrum β-lactamase determinant subtype was identified in one Fos Enteritidis isolate, which was located in a transferable unknown-type plasmid co-carrying and genes. Sequence homology analysis showed that this plasmid possessed high sequence similarity to previously reported - and -positive plasmids from strains, implying that plasmids carrying the gene might be disseminated among Enterobacterales. These findings highlight further challenges in the prevention and treatment of Enterobacteriaceae infections caused by plasmids containing .