Carbapenemase Genes Detection And Homology Analysis Of Carbapenem-resistant Klebsiella Pneumoniae

Objective: To investigate clinical distribution and to explore carbapenemase genes of carbapenem-resistant Klebsiella pneumoniae(CRKP)in a hospital.We try to find the dominant strain by homology analysis,so as to provide laboratory basis for prevention and control of spread of CRKP.Methods:(1)22 strains of CRKP isolated from clinical departments of a hospital between January and December 2017 were collected(excluding those duplicate strains from the patient),and the corresponding patient’s medical records were collected,including laboratory number,gender,age,history of hospitalization,length of hospital stay,basic diseases,invasive operation or treatment,use of antibiotics,whether to use hormones and prognosis.the isolation department,the source of specimens and the drug resistance to common antibiotics in clinic were also discussed.(2)Biochemical identification was performed by VITEK 2 Compact automatic microbial identification instrument and matching GN identification card,and the drug susceptibility identification was performed by AST-GN13 drug susceptibility card.The drug susceptibility results were checked by methods of Kirby-Bauer and Minimal Inhibitory Concentration,there are two good methods were carried out to detect carbapenemase phenotype,including modified Hodge test(MHT)and Carba NP test.The carbapenemase genes were amplified by polymerase chain reaction(PCR)and sequenced(blaKPC,blaSME,blaIMI,blaNDM-1,blaIMP,blaSIM,blaVIM,blaOXA-48)(3)The bacterial homology analysis was carried out by using multilocus sequence typing(MLST)and enterobacterial repetitive intergenic consensus-polymerase chain reaction(ERI C-PCR).Results:(1)Among the 22 strains of CRKP,7 strains were isolated from the department of neonat-ology,6 strains were isolated from the Intensive Care Unit(ICU),4 strains were isolated from the department of cerebrovascular diseases,and the rest from the department of respiratory medicine,thoracic surgery,general wards,hematology and nephrology.Among the 22 strains of CRKP,13 strains were isolated from sputum,5 strains were isolated from blood and 4 strains were isolated from urine.The 22 strains of CRKP maintained high drug resistance rate to clinical antibiotica except amikacin and polymyxin B(sensitivity rate>60%).(2)The resistance rates of 22 strains of CRKP to ertapenem(ETP),imipenem(IPM)and meropenem(MEM)were 100%.13 strains were positive for MHT and 14 strains were positive for Carba NP test.The results of PCR amplification and sequencing confirmed that blaKPC-2 was carried by all the 14 strains and one of the 14 strains carried blaKPC-2 and blaNDM-1.(3)The result of homology analysis showed that 22 stains of CRKP were divided into four sequence types(ST)by MLST,including ST11(14/22),ST875(6/22),ST1964(1/22),ST 571(1/22),and three types by ERIC-PCR,including type A(15/22),type B(6/22)and type C(1/22).Conclusion:(1)These strains of CRKP mainly distribute in the department of neonatology and ICU where the patients had serious basic diseases,low immunity and long stay in the hospital.These strains of CRKP mainly invade patients’ respiratory system and often maintain high resistance to most clinical antibiotics.(2)Carbapenemase is the main resistance mechanism of CRKP,and the main drug resistance gene carried by CRKP in this hospital is KPC-2,followed by NDM-1 gene.(3)The cloning epidemic of ST11 and ST875 CRKP existed in this hospital in 2017,and it is necessary to strengthen the prevention and control measures of nosocomial infection(NI).