Complete Sequence of a Novel IncR-F33:A-:B- Plasmid, pKP1034, Harboring fosA3, blaKPC-2, blaCTX-M-65, blaSHV-12, and rmtB from an Epidemic Klebsiella pneumoniae Sequence Type 11 Strain in China.

A high fosfomycin resistance rate was observed in Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) in our previous study, but little is known about its mechanisms. In this study, we explored the prevalence of plasmid-mediated fosfomycin resistance determinants among fosfomycin-resistant KPC-KP strains from a Chinese university hospital and determined the complete sequence of a novel fosA3-carrying plasmid isolated from an epidemic K. pneumoniae sequence type (ST) 11 strain. A total of 97 KPC-KP strains were studied, of which 57 (58.8%) were resistant to fosfomycin, including 44 (45.4%) harboring fosA3 and 1 harboring fosA. All fosA3-positive strains belonged to the dominant ST11-pulse type (PT) A clone according to multilocus sequence typing and pulsed-field gel electrophoresis, suggesting clonal dissemination. The fosA-positive isolate belonged to ST11-PTE. The fosA3-carrying plasmid pKP1034 is 136,848 bp in length and is not self-transmissible. It is a multireplicon plasmid belonging to IncR-F33:A-: B-. Besides fosA3, a variety of other resistance determinants, including blaKPC-2, rmtB, blaCTX-M-65, and blaSHV-12, are identified in pKP1034, which would allow for coselection of fosA3 by most β-lactams and/or aminoglycosides and facilitate its dissemination despite limited use of fosfomycin in China. Detailed comparisons with related plasmids revealed that pKP1034 is highly mosaic and might have evolved from alarming recombination of the blaKPC-2-carrying plasmid pKPC-LK30 from Taiwan and the epidemic fosA3-carrying plasmid pHN7A8 from mainland China.

Xiang DR ，Li JJ ，Sheng ZK ，Yu HY ，Deng M ，Bi S ，Hu FS ，Chen W ，Xue XW ，Zhou ZB ，Doi Y ，Sheng JF ，Li LJ ... -  《-》

Dissemination of a clone carrying a fosA3-harbouring plasmid mediates high fosfomycin resistance rate of KPC-producing Klebsiella pneumoniae in China.

Fosfomycin has been proposed as an adjunct to other active agents for treating KPC-producing Klebsiella pneumoniae infections. This study aimed to investigate the prevalence of fosfomycin resistance and plasmid-mediated resistance determinants among KPC-producing K. pneumoniae isolates from clinical samples in China. In total, 278 KPC-producing and 80 extended-spectrum β-lactamase (ESBL)-producing (non-KPC-producing) clinical K. pneumoniae isolates were collected in 12 hospitals from 2010 to 2013. Fosfomycin susceptibility testing was carried out using the agar dilution method. Phylogenetic clonal patterns were revealed by pulsed-field gel electrophoresis (PFGE). Isolates were screened for plasmid-mediated fosfomycin resistance genes (fosA, fosA3 and fosC2) by PCR amplification. A plasmid was completely sequenced by next-generation sequencing. The fosfomycin resistance rate in KPC-producers (60.8%; 169/278) was significantly higher than in ESBL-producers (12.5%; 10/80). In addition, 94 KPC-producing isolates were positive for fosA3 and most of them were clonally related. A 23939-bp plasmid (pFOS18) co-harbouring fosA3 and bla(KPC-2) was completely sequenced, revealing that the fosA3 gene was flanked by two copies of IS26; however, bla(KPC-2) was located on a Tn3-Tn4401 integration structure. Although the fosA3 and blaKPC-2 genes are located on different transposon systems, they are able to spread together worldwide through plasmid transfer. Dissemination of the clone carrying the fosA3-harbouring plasmid mediates the high fosfomycin resistance rate of KPC-producing K. pneumoniae in China. Fosfomycin as an alternative option for treating infections caused by KPC-producing K. pneumoniae should not be recommended in hospitals in which fosfomycin-resistant clonal dissemination is emerging.

Jiang Y ，Shen P ，Wei Z ，Liu L ，He F ，Shi K ，Wang Y ，Wang H ，Yu Y ... -  《-》

Molecular Epidemiology of Plasmid-Mediated Fosfomycin Resistance Gene Determinants in Klebsiella pneumoniae Carbapenemase-Producing Klebsiella pneumoniae Isolates in China.

Chen J ，Wang D ，Ding Y ，Zhang L ，Li X ... -  《-》

Characterization of a Multidrug-Resistant Porcine Klebsiella pneumoniae Sequence Type 11 Strain Coharboring bla(KPC-2) and fosA3 on Two Novel Hybrid Plasmids.

The occurrence of carbapenemase-producing Enterobacteriaceae (CPE) poses a considerable risk for public health. The gene for Klebsiella pneumoniae carbapenemase-2 (KPC-2) has been reported in many countries worldwide, and KPC-2-producing strains are mainly of human origin. In this study, we identified two novel hybrid plasmids that carry either blaKPC-2 or the fosfomycin resistance gene fosA3 in the multiresistant K. pneumoniae isolate K15 of swine origin in China. The blaKPC-2-bearing plasmid pK15-KPC was a fusion derivative of an IncF33:A-:B- incompatibility group (Inc) plasmid and chromosomal sequences of K. pneumoniae (CSKP). A 5-bp direct target sequence duplication (GACTA) was identified at the boundaries of the CSKP, suggesting that the integration might have been due to a transposition event. The blaKPC-2 gene on pK15-KPC was in a derivative of ΔTn6296-1 The multireplicon fosA3-carrying IncN-IncR plasmid pK15-FOS also showed a mosaic structure, possibly originating from a recombination between an epidemic fosA3-carrying pHN7A8-like plasmid and a pKPC-LK30-like IncR plasmid. Stability tests demonstrated that both novel hybrid plasmids were stably maintained in the original host without antibiotic selection but were lost from the transformants after approximately 200 generations. This is apparently the first description of a porcine sequence type 11 (ST11) K. pneumoniae isolate coproducing KPC-2 and FosA3 via pK15-KPC and pK15-FOS, respectively. The multidrug resistance (MDR) phenotype of this high-risk K. pneumoniae isolate may contribute to its spread and its persistence.IMPORTANCE The global dissemination of carbapenem resistance genes is of great concern. Animals are usually considered a reservoir of resistance genes and an important source of human infection. Although carbapenemase-producing Enterobacteriaceae strains of animal origin have been reported increasingly, blaKPC-2-positive strains from food-producing animals are still rare. In this study, we first describe the isolation and characterization of a carbapenem-resistant Klebsiella pneumoniae ST11 isolate, strain K15, which is of pig origin and coproduces KPC-2 and FosA3 via two novel hybrid plasmids. Furthermore, our findings highlight that this ST11 Klebsiella pneumoniae strain K15 is most likely of human origin and could be easily transmitted back to humans via direct contact or food intake. In light of our findings, significant attention must be paid to monitoring the prevalence and further evolution of blaKPC-2-carrying plasmids among the Enterobacteriaceae strains of animal origin.

Zhang W ，Zhu Y ，Wang C ，Liu W ，Li R ，Chen F ，Luan T ，Zhang Y ，Schwarz S ，Liu S ... -  《mSphere》

The plasmid-mediated fosfomycin resistance determinants and synergy of fosfomycin and meropenem in carbapenem-resistant Klebsiella pneumoniae isolates in Taiwan.

Epidemiology of fosfomycin susceptibility and the plasmid-mediated fosfomycinase genes of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates in Taiwan remain unclear. 642 CRKP clinical isolates were collected from a nation-wide surveillance study (16 hospitals) in Taiwan in 2012-2013. Antimicrobial susceptibilities were determined. PFGE and MLST determined the clonal relatedness. Carbapenemases and fosfomycinases genes were detected by PCR, and their flanking regions were determined by PCR and sequencing. Synergistic activity of meropenem with fosfomycin was examined by the checkerboard method. In total, 36.4% (234/642) of CRKP isolates in Taiwan were resistant to fosfomycin. Among 234 fosfomycin-resistant CRKP isolates, PFGE analysis revealed 81 pulsotypes. Pulsotype XXIII (n = 63) was predominant and belonged to ST11. 71 had carbapnemases (65 blaKPC-2-positive, 1 blaVIM-1-positive and 5 blaIMP-8-positive) and 62 had fosfomycinases (35 fosA3-positive and 27 foskp96-positive). Only 18.5% (5/27) of foskp96-positive isolates carried foskp96 and blaKPC-2, while 71.4% (25/35) of fosA3-positive isolates contained fosA3 and blaKPC-2. There were five types of flanking sequences for fosA3, and 85.7% (30/35) of fosA3 genes were flanked by IS26, suggesting possible horizontal gene transfer. Synergistic effect of fosfomycin and meropenem was observed in all 25 randomly selected pulsotype XXIII strains (100%; 25/25), even those containing fosfomycinase (48%, 12/25) or carbapnemase (96%, 24/25). A clone (pulsotype XXIII, ST11) has been found to be prevailing among fosfomycin-resistant CRKP in Taiwan. According to the in vitro data, the combination of fosfomycin and meropenem is a potentially alternative choice.

Tseng SP ，Wang SF ，Ma L ，Wang TY ，Yang TY ，Siu LK ，Chuang YC ，Lee PS ，Wang JT ，Wu TL ，Lin JC ，Lu PL ... -  《-》