The Clinical Risk Factors, Drug Resistance And Homology Analysis Of Carbapenem-resistant Citrobacter Freundii Isolates From A Hospital In Chongqing

Objective: To analyze the clinical risk factors,drug resistance and molecular epidemiology of Carbapenem-Resistant Citrobacter freundii(CRCF)Isolates.Methods: The clinical data of 138 patients infected with Citrobacter freundii from January 2013 to March 2018 were collected from the Second Affiliated Hospital of Chongqing Medical University,and were divided into two groups,including 32 case of CRCF infection and 106 case of Non-CRCF(NCRCF)infection;Clinical risk factors of CRCF were analyzed by Chi-square test and mulivariate Logistic regression analysis;Multilocus sequence typing(MLST)was performed to analyze the homology of the CRCF isolates;PCR was used to detect bacterial resistance genes.Results: A total of 138 patients with Citrobacter freundii infections were enrolled in this study,The detection rate of CRCF was 23.2%;Multivariate logistic regression analysis showed that surgical operation(OR=4.057,95%CI=1.574~10.458,P=0.004)and tumour(OR=2.938,95%CI=1.160~7.441,P=0.023)were independent risk factors for CRCF infection;CRCF strains are characterized by multiple drug resistance.They are highly resistant to antibiotics commonly used in clinical practice and carry multiple drug resistance genes.β-lactamases,aminoglycosides and quinolones resistance genes are detected in most of the strains,with a carrying rate of 70.8%;A total of 7 MLST clones were found,the main types were ST22(n=8)and ST115(n=8).Two new STs have been confirmed by the PubMlst datebase and named ST115 and ST116.ST22,ST63,ST79,ST116 and ST118 strains were found to carry NDM-1 drug resistance genes.ST115 strains mainly carried IMP resistance genes(6strains),while the other two strains carried KPC resistance genes.Conclusion: Surgical operation and tumour were independent risk factors for CRCF infection;CRCF strains all carry multiple drug resistance genes,Besides β-lactamase(ESBLs,AmpC and carbapenems)drug resistance genes,possess several additional resistance genes such as aminoglycoside and quinolone drug resistance genes.The advantage clones of CRCF infection are ST22 and ST115;ST22,ST63,ST79,ST116 and ST118 strains all carry NDM-1 drug resistance genes,and ST115 strains mainly carry IMP drug resistance genes.Therefore it is necessary to strengthen the monitor and control of CRCF infection,to prevent the spread of CRCF.