| Objective To investigate the infection risk factors,antibiotic resistance mechanism,virulence characteristics,homology of carbapenem resistant Klebsiella pneumoniae（CRKP）isolated from inpatients in the General Hospital of Ningxia Medical University,in order to provide reference for clinical anti-infective program and nosocomial surveillance.Methods（1）The sample types,isolation departments and antibiotic sensitivity results of CRKP strains isolated from the General Hospital of Ningxia Medical University from January2015 to December 2019 were counted by WHONET5.6 software,and the clinical information of patients was collected,a 1:1 case-control study was designed,and univariate and multivariate Logistic regression were used to screen the risk factors of infection.（2）The collected strains were isolated and cultured,and identified and confirmed by antbiotic sensitivity test.The phenotype of carbapenease was detected by modified hydrocarbon enase inactivation test（m CIM）combined with EDTA-modified hydrocarbon enase inactivation test（e CIM）,and the virulent strains were screened by string test.（3）PCR was used to amplify 7 resistance genes,including common ESBLs,carba-penem gene,6 capsule serotypes and 10 virulence genes,and some positive products were sequenced.（4）The molecular epidemiology of CRKP was analyzed by multilocus sequence typing（MLST）,and the genetic relationship of virulent strains was analyzed by pulsed field gel electrophoresis（PFGE）.Results（1）The information of 167 strains CRKP was collected.The results of antibiotic sensitivity showed that the antibiotic resistance rates of cephalosporins and monocyclicβ-lactams were more than 80%,while the resistance rates of amikacin was lower than 35%.The main types of specimens were sputum from respiratory tract,and the departments with high isolation rate were PICU and ICU.According to the statistical clinical information,it was found that the male was 65.87%（110/167）,and the age span was large,mainly concentrated in 0-1-year-old infants and 41-80-year-old people,43.71%（73/167）and 39.52%（66/167）,respectively.（2）The results of multivariate analysis showed that carbapenem antibiotics（OR=13.500,95%CI:3.771-48.329）,antibiotics used for more than 14 days（OR=34.667,95%CI:4.899-245.329）were independent risk factors for CRKP infection.（3）A total of 103 CRKP strains collected and cultured were tested by m CIM combined with e CIM.The results showed that 91.26%（94/103）CRKP produced carbapenem,of which67.02%（63/94）produced metallo-penicillinase and 35.11%（31/94）produced serine carbapenem.The results of antibiotic resistance genes showed that in addition to bla VIMnegative,the detection rates were bla TEM79.61%（82/103）,bla SHV60.19%（62/103）,bla NDM50.49%（52/103）,bla KPC33.00%（34/103）,bla OXA-4822.33%（23/103）,bla IMP10.68%（11/103）.Combined with the results of antibiotic resistance genes,it was found that phenotypic test showed that the sensitivity and specificity of carbapenem produced by CRKP strain were 94.25%（82/87）and 25.00%（4/16）,respectively,and the sensitivity and specificity of serinase and metalloenzyme were low.Sequencing comparison showed that bla KPCpositive all belonged to KPC-2 type,while bla NDMpositive mainly belonged to NDM-5type 80.77%（42/52）.MLST typing showed that there were 18 ST types,and ST11 type was the dominant type.（4）Among the 103 strains of CRKP,9.71%（10/103）were positive by string test,which were highly virulent strains;4.85%（5/103）of K1 type and 10.68%（11/103）of K57 type were detected in capsular serotype,but no other 4 strains were detected.The detection rates of fim-H and ent-B were 73.79%（76/103）and 56.37%（56/103）respectively,and the detection rate was generally low.（5）The detection rate of virulence genes of 10 CR-HvKP strains was high,and the results of PFGE showed that the largest number is D cluster.No outbreak of this strain was found.Conclusion Invasive operation and antibiotic exposure may be the important causes of CRKP infection in hospital.The main mechanism of antibiotic resistance of CRKP strain is NDM-5 type carbapenem,and ST11 type is the dominant epidemic strain in hospital.The detection rate of virulence gene was low in CRKP and high in CR-HvKP.No outbreak of CR-HvKP strain was found.In a word,at present,the antibiotic resistance of CRKP strain in hospital is severe,and the CR-HvKP strain with high antibiotic resistance and high virulence has been detected,which should attract the attention of all parties. |
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