We aimed to characterize NDM-5-producing Enterobacteriaceae from aquatic products in Guangzhou,China.A total of 196 intestinal samples of grass carp collected in 2019 were screened for carbapenemase genes.Characteriza...We aimed to characterize NDM-5-producing Enterobacteriaceae from aquatic products in Guangzhou,China.A total of 196 intestinal samples of grass carp collected in 2019 were screened for carbapenemase genes.Characterization of bla_(NDM-5) positive isolates and plasmids was determined by antimicrobial susceptibility testing,conjugation experiments,Illumina HiSeq,and Nanopore sequencing.One Citrobacter freundii and six Escherichia coli strains recovered from seven intestinal samples were verified as bla_(NDM-5) carriers(3.57%,7/196).The bla_(NDM-5) genes were located on the lncX3(n=5),lncHI2(n=1),or lncHI2-lncF(n=1)plasmids.All bla_(NDM-5)-bearing plasmids were transferred by conjugation at frequencies of~10^(-4)-10^(-6).Based on sequence analysis,the lncHI2 plasmid pHNBYF33-1 was similar to other bla_(NDM-5)-carrying lncHI2 plasmids deposited in GenBank from Guangdong ducks.In all lncHI2 plasmids,bla_(NDM-5)was embedded in a novel transposon,Tn7057(IS3000-△ISAba125-IS5-△ISAba125-bla_(NDM-5)-bleMBL-trpF-tat-△dct-IS26-△umuD-△ISKox3-IS3000),which was identical to the genetic structure surrounding bla_(NDM-5)found in some IncX3 plasmids.The lncHI2-lncF hybrid plasmid pHNTH9F11-1 was formed by homologous recombination of the bla_(NDM-5)-carrying lncHI2 plasmid and a heavy-metal-resistant IncF plasmid through△Tn1721 To the best of our knowledge,this is the first report on the characterization of bla_(NDM-5)-bearing plasmids in fish in China.The lncHI2 plasmid pHNBYF33-1 may be transmitted from ducks,considering the common duck-fish freshwater aquaculture system in Guangdong.Tn7051 is likely responsible for the transfer of bla_(NDM-5) from lncX3 to lncHI2 plasmids in Enterobacteriaceae,resulting in the expansion of transmission vectors of bla_(NDM-5).展开更多
Conjugative transfer of antibiotic resistance genes(ARGs)by plasmids is an important route for ARG dissemination.An increasing number of antibiotic and nonantibiotic compounds have been reported to aid the spread of A...Conjugative transfer of antibiotic resistance genes(ARGs)by plasmids is an important route for ARG dissemination.An increasing number of antibiotic and nonantibiotic compounds have been reported to aid the spread of ARGs,highlighting potential challenges for controlling this type of horizontal transfer.Development of conjugation inhibitors that block or delay the transfer of ARG-bearing plasmids is a promising strategy to control the propagation of antibiotic resistance.Although such inhibitors are rare,they typically exhibit relatively high toxicity and low efficacy in vivo and their mechanisms of action are inadequately understood.Here,we studied the effects of dihydroartemisinin(DHA),an artemisinin derivative used to treat malaria,on conjugation.DHA inhibited the conjugation of the IncI2 and IncX4 plasmids carrying the mobile colistin resistance gene(mcr-1)by more than 160-fold in vitro in Escherichia coli,and more than two-fold(IncI2 plasmid)in vivo in a mouse model.It also suppressed the transfer of the IncX3 plasmid carrying the carbapenem resistance gene bla_(NDM-5)by more than twofold in vitro.Detection of intracellular adenosine triphosphate(ATP)and proton motive force(PMF),in combination with transcriptomic and metabolomic analyses,revealed that DHA impaired the function of the electron transport chain(ETC)by inhibiting the tricarboxylic acid(TCA)cycle pathway,thereby disrupting PMF and limiting the availability of intracellular ATP for plasmid conjugative transfer.Furthermore,expression levels of genes related to conjugation and pilus generation were significantly down-regulated during DHA exposure,indicating that the transfer apparatus for conjugation may be inhibited.Our findings provide new insights into the control of antibiotic resistance and the potential use of DHA.展开更多
基金supported by the National Natural Science Foundation of China(31625026,32141002)Innovation Team Project of Guangdong University(2019KCXTD001)。
文摘We aimed to characterize NDM-5-producing Enterobacteriaceae from aquatic products in Guangzhou,China.A total of 196 intestinal samples of grass carp collected in 2019 were screened for carbapenemase genes.Characterization of bla_(NDM-5) positive isolates and plasmids was determined by antimicrobial susceptibility testing,conjugation experiments,Illumina HiSeq,and Nanopore sequencing.One Citrobacter freundii and six Escherichia coli strains recovered from seven intestinal samples were verified as bla_(NDM-5) carriers(3.57%,7/196).The bla_(NDM-5) genes were located on the lncX3(n=5),lncHI2(n=1),or lncHI2-lncF(n=1)plasmids.All bla_(NDM-5)-bearing plasmids were transferred by conjugation at frequencies of~10^(-4)-10^(-6).Based on sequence analysis,the lncHI2 plasmid pHNBYF33-1 was similar to other bla_(NDM-5)-carrying lncHI2 plasmids deposited in GenBank from Guangdong ducks.In all lncHI2 plasmids,bla_(NDM-5)was embedded in a novel transposon,Tn7057(IS3000-△ISAba125-IS5-△ISAba125-bla_(NDM-5)-bleMBL-trpF-tat-△dct-IS26-△umuD-△ISKox3-IS3000),which was identical to the genetic structure surrounding bla_(NDM-5)found in some IncX3 plasmids.The lncHI2-lncF hybrid plasmid pHNTH9F11-1 was formed by homologous recombination of the bla_(NDM-5)-carrying lncHI2 plasmid and a heavy-metal-resistant IncF plasmid through△Tn1721 To the best of our knowledge,this is the first report on the characterization of bla_(NDM-5)-bearing plasmids in fish in China.The lncHI2 plasmid pHNBYF33-1 may be transmitted from ducks,considering the common duck-fish freshwater aquaculture system in Guangdong.Tn7051 is likely responsible for the transfer of bla_(NDM-5) from lncX3 to lncHI2 plasmids in Enterobacteriaceae,resulting in the expansion of transmission vectors of bla_(NDM-5).
基金supported in part by grants from the Laboratory of Lingnan Modern Agriculture Project (NT2021006)National Key Research and Development Program of China (2022YFD1800400)。
文摘Conjugative transfer of antibiotic resistance genes(ARGs)by plasmids is an important route for ARG dissemination.An increasing number of antibiotic and nonantibiotic compounds have been reported to aid the spread of ARGs,highlighting potential challenges for controlling this type of horizontal transfer.Development of conjugation inhibitors that block or delay the transfer of ARG-bearing plasmids is a promising strategy to control the propagation of antibiotic resistance.Although such inhibitors are rare,they typically exhibit relatively high toxicity and low efficacy in vivo and their mechanisms of action are inadequately understood.Here,we studied the effects of dihydroartemisinin(DHA),an artemisinin derivative used to treat malaria,on conjugation.DHA inhibited the conjugation of the IncI2 and IncX4 plasmids carrying the mobile colistin resistance gene(mcr-1)by more than 160-fold in vitro in Escherichia coli,and more than two-fold(IncI2 plasmid)in vivo in a mouse model.It also suppressed the transfer of the IncX3 plasmid carrying the carbapenem resistance gene bla_(NDM-5)by more than twofold in vitro.Detection of intracellular adenosine triphosphate(ATP)and proton motive force(PMF),in combination with transcriptomic and metabolomic analyses,revealed that DHA impaired the function of the electron transport chain(ETC)by inhibiting the tricarboxylic acid(TCA)cycle pathway,thereby disrupting PMF and limiting the availability of intracellular ATP for plasmid conjugative transfer.Furthermore,expression levels of genes related to conjugation and pilus generation were significantly down-regulated during DHA exposure,indicating that the transfer apparatus for conjugation may be inhibited.Our findings provide new insights into the control of antibiotic resistance and the potential use of DHA.
