Gene Detection And Resistant Mechanisms Of PER Type Extended Spectrum β-Lactamases

Antimicrobial resistance has become a serious healthy threat with the wide use of antimicrobial agents.Besides,production of extended spectrumβ-lactamases（ESBLs）is the most important mechanism.PER type ESBLs is not as prevalent as TEM,SHV,CTX-M,but due to its extensive drug resistance,transmission diversity,and being an independent risk factor for poor prognosis of patients,the detection and monitoring of PER are of great significance for the prevention and treatment of drug-resistant bacteria.Our study describes,for the first time,the identification of a PER-1 ESBL in a non-O1,non-O139 Vibrio cholera strain.Through conjugation test,plasmid extraction,S1-PFGE,southern blot,reverse PCR and long PCR,we found bla_PER-1 is carried on a conjugative and broad-host-range IncA/C plasmid;a Tn1696-like transposon is located in this plasmid,and a highly mobile ISCR1 element is embedded in this transposon and is present in the form of a small circular molecule as well.Then we carried out the screening of bla_PER among the Gram-negative bacilli with resistance to ceftazidime,cefotaxim,andcefepime based on the previous design approach.The aim is to characterize genotypes,molecular epidemiology,location,genetic environment,and possible transmission of bla_PER.In a conclusion,bla_PER is widespread in Gram-negative bacilli in China.Our results indicate that ISCR1 plays a major role in the mobilization of bla_PER among clinical bacterial pathogens,forming a circular molecule.Moreover,diverse and complex mobile genetic elements,such as IS26,Tn21,MITE,and Tn1696,may be involved in the horizontal transfer of bla_PER.