Investigation And Study On ?-lactam Resistance Gene In Serratia Marcescens Carbapenems-resistant

Objective:To investigate and study ?-lactam resistance gene carrying cases of the clinical isolates of Serratia marcescens carbapenems-resistant,which were collected from the First and the Second Affiliated Hospital of Anhui Medical University.Methods: From 2013 to 2015,a total of 242 clinical isolates of Serratia marcescens were collected(155 strains from the First Affiliated Hospital of Anhui.Medical University and 87 strains from the Second Affiliated Hospital of Anhui Medical University),using Vitek-2 Compact automatic microbial system and the drug sensitivity test was performed on the identification,screened 18 strains of imipenem-resistant,1 strain of intermedated resistance to imipenem.All 19 strains were confirmed resistant to carbapenems by ertapenem and meropenem susceptibility disk test(K-B method).Modified Hodge test and EDTA synergy test were used for detecting carbapenemase and PCR was used for detecting bla KPC,bla NMC,bla IMP,bla GIM,bla VIM,bla OXA-23 carbapenemase genes and bla VEB,bla PER,bla TEM,bla SHV,bla CTX-M-1,bla CTX-M-2,bla CTX-M-9 extended spectrum?-lactamase genes and then positive results were sequenced and blasted to determine genotype.Results:The results of drug susceptibility test showed that 19 strains to meropenem and ertapenem,aztreonam,ciprofloxacin,cefazolin,ceftriaxone and cefotaxime were resistant;To imipenem,18 strains were resistant and 1 strain was intermdated resistant.All 19 strains were sensitive to Amikacin;Gentamicin sensitivity rate was 57.9%;The sensitivity rate of tobramycin was 26.3%;The sensitivity rate of cefotetan,ceftazidime,cefepime were 15.8%,15.8% and 10.5% respectly;The sensitivity rate of Levofloxacin,piperacillin / tazobactam all were 5.3%.Resluts of modified Hodg test were positive in 18 strains,and negative in 1 strain.EDTA synergy tests were all negative.PCR amplification and DNA sequencing showed that 7 strains were carrying bla KPC-2 gene,6 strains were carrying bla CTX-M-14 gene,3 strains were carrying bla SHV-11 gene,2 strains were carrying bla SHV-12 gene,1 strain was carrying bla OXA-23 gene.Neither bla NMC,bla IMP,bla GIM,bla VIM carbapenemase genes nor bla VEB,bla PER,bla TEM,bla CTX-M-1,bla CTX-M-2 extended spectrum ?-lactamase genes were detected in all 19 strains.Conclusion:The clinical isolates of Serratia marcescens carbapenems-resistant in two Affiliated Hospital of Anhui Medical University were serious in drug resistance,mainly carrying KPC-2 and CTX-M-14 resistance gene with carrying rate of 36.8% and 31.6% respectly.