Acquired Resistance-related Genes And Clinical Characteristic In Extensively Drug-resistant Klebsiella Pneumoniae

Objective: 1.To investigate the distribution of acquired resistance-related genes and markers of mobile genetic elements,and their relationships in Extensively drug-resistant Klebsiella pneumoniae(PDR-KPN).2.To investigate the clinical characteristic of 9 patients infected by PDR-KPN.3.To investigate the risk factors for the acquisition of nosocomial CRKP infections.Methods: 1.Thirty-one strains of PDR-KPN were isolated during January 2013 to December 2013 from three hospitals.Acquired resistance genes to β-lactames,aminoglycosides,quinolones and genetic markers of mobile genetic elements were analyzed by PCR.The sample cluster analysis was used to investigate their relationships.2.Patients with infections caused by XDR-KP were identified by the ICU’s electronic database.The medical records of these patients were reviewed.Data for several variables,including demographic and clinical information,as well as results of laboratory and imaging tests of the patients were collected using a specially designed case report form.3.We conducted a case-control study with data collected from sixty patients with nosocomially acquired CRKP infection between January 2013 and December 2015.Controls were selected at a ratio of 1:1 from patients with nosocomial carbapenem-susceptible Klebsiella pneumoniae(CSKP)infection and were matched with CRKP cases for site of infection and the date of isolation.Chi-square test and logistic regression were used for statistical analysis.Results: 1.Acquired β-lactam-resistance genes,acquired aminoglycoside-resistance genes and the mutation of gyrA gene were existent in all strains.The positive rate of blaKPC,ISKpn6 and KPC-ISKpn6 were 100%.Strains isolated from three hospitals were in three different clustetrs respectively.High correlation existed between strains from hospital B and hospital C.2.ALL of 9 XDR-KP infections were HAP,including 5 males and 4 females.The mean age was 66±12 years,the mean hospital stay was 46±19 days.Infections occurred at a mean of 30±13 days after admission in ICU.4 patients were treated with tigecycline combined with other antimicrobial agents,3 patients were treated with fosfomycin combined with other antimicrobial agents and 2 patients were treated with original therapeutic schedule.After treatment,clinical success were recorded in 6 patients,clinical failure were recorded in 2 patients and clinical uncertainty were recorded in 1 patient.3.Bivariable analysis showed that days of hospital stay≥14,days exposure to antibiotics ≥14,number of antibiotics kinds prior to isolation of KP≥2,exposure to carbapenems,exposure to glycopeptides,exposure to antifungal agents,number of coexisted bacterior ≥2,coexisted with fungus and KP colonization prior to KP infection were related to CRKP infection(P﹤0.05).The multivariable analysis showed that exposure to carbapenems(95%CI: 1.137-14.471,P ﹤ 0.05))was independent risk factors for nosocomial CRKP infections.Conclusions: 1.In this group of PDR-KPN,acquired resistance related genes may be associated with resistant phenotypes of bacterial pathogens.There were clone spread between strains.2.Tigecycline or fosfomycin combined with other antimicrobial agents may be a beneficial adjunctive treatment in the management of HAP caused by XDR-KP.3.Several factors are related to CRKP infections.Exposure to carbapenems is independent risk factor for the acquisition of nosocomial CRKP infections.