AUTHOR=Cheng Ke , Fang Liang-Xing , Ge Qian-Wen , Wang Dong , He Bing , Lu Jia-Qi , Zhong Zi-Xing , Wang Xi-Ran , Yu Yang , Lian Xin-Lei , Liao Xiao-Ping , Sun Jian , Liu Ya-Hong 

TITLE=Emergence of fosA3 and blaCTX–M–14 in Multidrug-Resistant Citrobacter freundii Isolates From Flowers and the Retail Environment in China

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.586504

DOI=10.3389/fmicb.2021.586504

ISSN=1664-302X

ABSTRACT=We examined the prevalence and transmission of the fosA3 gene among Citrobacter freundii isolates from flowers and their surrounding environments. We identified 11 fosfomycin-resistant C. freundii strains (> 256 µg/mL) from 270 samples that included petals (n=7), leaves (n=2), dust (n=1) and water (n=1). These 11 isolates were multidrug-resistant and most were simultaneously resistant to fosfomycin, cefotaxime, ciprofloxacin and amikacin. Consistently, all 11 isolates also possessed blaCTX-M-14, blaCMY-65/122, aac(6')-Ib-cr, qnrS1, qnrB13/6/38 and rmtB. These fosA3-postive isolates were assigned to two distinct PFGE patterns and one (n=9) predominated indicating clonal expansion of fosA3-positive isolates across flower markets and shops. Correspondingly, fosA3 was co-transferred with blaCTX-M-14 via two plasmid types by conjugation possessing sizes of 110 kb (n=9) and 260 kb (n=2). Two representatives were fully sequenced and p12-1 and pS39-1 possessed one and two unclassified replicons, respectively. These plasmids shared a distinctive and conserved backbone in common with fosA3-carrying C. freundii and other Enterobacteriaceae from human and food animals. However, the fosA3-blaCTX-M-14-containing multidrug resistance regions on these untypable plasmids were highly heterogeneous. To the best of our knowledge, this is the first report of fosA3 and blaCTX-M-14 that were present in bacterial contaminants from flower shops and markets. These findings underscore a public health threat posed by untypable and transferable p12-1-like and pS39-1-like plasmids bearing fosA3-blaCTX-M-14 that could circulate among Enterobacteriaceae species and in particular C. freundi in environmental isolates.