| Objective:To understand the drug resistance,virulence and molecular epidemiological characteristics of CAZ-AVI-resistant CRKP in the First Affiliated Hospital of Nanchang University,and to analyze the risk factors for clinical infection of CAZ-AVI-resistant CRKP to provide a basis for clinical prevention and treatment.Methods:Non-replicated CAZ-AVI-resistant CRKP and non-replicated CRKP determined by drug sensitivity tests were collected from inpatients at the First Affiliated Hospital of Nanchang University October 2021 to October 2022.Clinical data of those patients were collected to analyze the risk factors for CAZ-AVI-resistant CRKP infection.The molecular epidemiology of CAZ-AVI-resistant CRKP were analyzed by detecting their MLST and PFGE.The virulence gene distribution characteristics of CAZ-AVI-resistant were analyzed by detecting virulence genes.The resistance mechanism of CAZ-AVI-resistant were analyzed by detecting carbapenem resistance genes、ultra broad-spectrumβ-lactamase genes、quinolone resistance genes、aminoglycoside resistance genes and membrane pore channel protein genes.Results:1.The specimen type of the 47 ceftazidime-avibactam-resistant CRKP was mainly Respiratory specimen（32/47,68%）.the source of the specimens was mainly from ICU（38/47,80.9%）.2.Except polymyxin and tigecycline,CAZ-AVI-resistant CRKP were resistant to almost all commonly used antimicrobial drugs（resistance rate>90.0%）.The resistance rate of CAZ-AVI-resistant CRKP to multiple antimicrobial drugs was significantly higher than that of CRKP（P<0.05）.3.Comparing the clinical data of patients with CAZ-AVI-resistant CRKP with those of patients with CRKP infection,statistically significant differences were found between the two groups in terms of pre-infection cerebral hemorrhage,bronchoscopy,tracheotomy,length of antibiotic exposure and≥3 types of antibiotic exposure（P<0.05）.Multifactorial logistic regression equations showed that tracheotomy,length of antibiotic exposure,and≥3 types of antibiotic exposure were risk factors for CAZ-AVI-resistant CRKP infection（P<0.05）.4.CAZ-AVI resistant CRKP PFGE band types are mainly J-band types in 47strains.CAZ-AVI resistant CRKP were detected 11 types,and ST11 was dominant type in 47 strains.CAZ-AVI resistant CRKP were detected 5 types of capsular serotypes and K57 were dominant capsular serotypes in 47 strains.ST11-K57 were the main prevalent clones of CAZ-AVI-resistant CRKP in he First Affiliated Hospital of Nanchang University.In the 47 strains of CAZ-AVI resistant CRKP,the carriage rate of hypermucoviscosity phenotype genes was 100%,the carriage rate of iron carrier genes was 100%,the carriage rate of Peg-344 virulence genes was 51.1%,the carriage rate of≥2 virulence genes was 100%,the carriage rate of≥3 virulence genes was 91.5%and the carriage rate of 5 virulence genes was 10.6%.5.Results of PCR for drug resistance genes:all carried bla TEM,bla CTXM and bla SHV,97.9%carried quinolone resistance genes,87.2%carried aminoglycoside resistance genes,MBL resistance genes carriage rate of 63.8%,bla OXA48-like carriage rate of 80.9%,bla KPC carriage rate 100%.The deletion rates of Ompk35 and Ompk36genes were 66.0%and 61.7%,respectively,and 40.4%of both Ompk36 and Ompk35genes were missing.6.Comparing with the MBL-producing group of CAZ-AVI-resistant CRKP,The bla OXA48-like carriage rate and the deletion of membrane pore protein genes Ompk35and Ompk36 was significantly higher in CAZ-AVI-resistant CRKP in the non-MBL-producing group（P<0.05）.Conclusions:1.Tracheotomy,antibiotic exposure days and≥3 types of antibiotic exposure were risk factors for CAZ-AVI-resistant CRKP infection.2.ST11-K57 is the main prevalent clone of CAZ-AVI-resistant CRKP bacteria in the First Affiliated Hospital of Nanchang University.3.The mechanism of CRKP resistance to CAZ-AVI is mainly the production of MBL,followed by the deletion of membrane pore channel protein. |
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