Study On The Mechanism Of Enzyme-producing Resistance,risk Factors And Prognosis Of Carbapenem-resistant Klebsiella Pneumoniae

Objective To explore the enzyme-producing mechanism,risk factors and prognosis of carbapenem-resistant Klebsiella pneumoniae isolated from inpatients in Nanjing Hospital affiliated to Nanjing Medical University,in order to improve clinicians’ understanding of CRKP infection,guide clinical rational drug use,and reduce the morbidity and mortality of such patients.Methods The non-repetitive CRKP strains isolated from clinical samples in the microbiology laboratory of the hospital from September 2017 to December 2020 were randomly collected.A total of 77 strains were retained after the colonization strains were removed.Drug susceptibility was measured by disk diffusion test,carbapenem phenotype was detected by modified hodge test and enzyme inhibitor enhancement test,carbapenem,extended-spectrum β-lactamase and cephalosporinase genes were detected by PCR and DNA sequencing.Retrospective analysis and case-control study were designed to analyze the clinical data of CRKP group and CSKP group,including general conditions,underlying diseases,history of antibiotic use within 3 months,invasive operation,history of immunosuppressive therapy within 3 months and antibiotic treatment regimen,etc.Univariate and multivariate logistic regression analysis were used to explore the risk factors of CRKP infection and prognosis.Results1.All of 77 CRKP strains were resistant to imipenem,meropenem and ertapenem.The resistance rate to ciprofloxacin,ceftriaxone,ampicillin/sulbactam,levofloxacin,piperacillin/tazobactam was more than 90%,and it was sensitive to amikacin,sulfamethoxone,CZA and tegacycline.2.A total of 72 strains(93.5%)were positive for modified Hodge test,and the results of enzyme inhibitor enhancement test showed that 72 strains(93.5%)produced KPC-2,2 strains(2.6%)produced NDM-1,respectively.3.The results of gene detection showed that 75 strains(97.4%)carried KPC gene,which were confirmed as KPC-2;31 strains(40.3%)carried NDM gene,22 of them were confirmed as NDM-1,3 of them were NDM-4,the other 6 were NDM-5,that 18 strains(23.4%)carried TEM gene,15 of them were TEM-1,1 of them was TEM-104,that 41 strains(53.2%)carried SHV gene,28 of them were SHV-131,10 of them were SHV-171,the other 3 were SHV-11,SHV-23,SHV-27,and that 46 strains(59.7%)carried CTX-M-1 group gene,3 were CTX-M-3,42 were CTX-M-15,1 was CTX-M-28.More over,all 77 strains carried CTX-M-9 group gene,74 strains carried CTX-M-65,1 strain was CTX-M-14,2 strains were CTX-M-27;4 strains(5.2%)carried DHA gene,which were all confirmed as DHA-1.4.Most of the infected patients were male,mainly from neurosurgery(29.9%),respiratory department(19.5%),ICU(15.6%)and neurology(10.4%).The main types of specimens were sputum(72.7%),urine(16.9%)and blood(6.5%).5.Respiratory diseases,use of carbapenem drugs,use of quinolones,use of third generation cephalosporin/enzyme inhibitors,use of penicillin/enzyme inhibitors,use of tegacycline,treatment of gram-positive cocci within 3 months,gastric tube catheterization,operation within 1 month,hypoproteinemia,days of hospitalization before positive culture,total days of hospitalization were risk factors of CRKP infection(P<0.05).Carbapenem antibiotics use within 3 months(OR=7.478,95%CI:2.016-27.743,P=0.003)and quinolone use within 3 months(OR=5.001,95%CI:1.473-16.978,P=0.010)were independent risk factors for CRKP infection.Cerebrovascular disease or brain trauma,cancer,deep venipuncture,mechanical ventilation,bloodstream infection,ICU occupancy history,immunosuppressive therapy within 3 months and high APACHE Ⅱ were risk factors of death in patients with CRKP infection(P<0.05).High APACHE Ⅱ(OR=1.239,95%CI:1.024-1.499,P=0.028)were independent risk factors of death in patients with CRKP infection.Conclusion1.CRKP strains were highly resistant to common antibiotics,and were less resistant to tegacycline,amikacin and sulfamethoxazole,and had the lowest resistance to ceftazidime/avibactam.2.KPC-2 is the most common carbapenem enzyme gene in CRKP strains in our hospital.3.Carbapenem or quinolone antibiotics use within 3 months were independent risk factors for CRKP infection,while high APACHE Ⅱ was an independent risk factor for death.