Correlation Analysis Of Beta-lactam Resistance Mechanism And Virulence Factors In Klebsiella Pneumoniae

Objective: In this study,we aimed to analyze the frequency of antibiotic resistance profile and virulence factors of Klebsiella pneumoniae isolated from our hospital,as well as the correlation with biofilm formation.Method: 96 clinical isolates of Klebsiella pneumoniae from August 2018 to June 2019 were collected.The minimal inhibitory concentration(MIC)of antibiotic was determined by broth microdilution method.The phenotype were identified by double-disc synergy test(DDST),modified Hodge test(MHT),modified carbapenem inactivation method(m CIM)and string test.The biofilm formation ability of the strain was measured by crystal violet staining method.PCR were performed to detect the antibiotic resistance genes,virulence factors and multilocus sequence typing(MLST).Result: 1.A total of 96 Klebsiella pneumoniae strains were mainly distributed in neurosurgery department(20,20.8%)and ICU department(13,13.5%).The samples were mainly derived from sputum(54,56.3%).Most of patients(67,69.8%)were used invasive procedures and/or retention of medical devices during hospitalization.Thirty-two strains with hypermucoviscous(HM)phenotype showed significantly lower resistance to the other 11 antibacterial agents than that of non-HM strains except ceftazidime(CAZ),cefoxitin(FOX),meropenem(MEM),imipenem(IMP),amtronam(ATM)and levofloxacin hydrochloride(LVX).The detection rate of biofilm positive strains was significantly higher than that of biofilm negative strains in multi-drug resistance(MDR)Klebsiella pneumoniae strains(χ2=6.192,P=0.013).Thirty-three extended spectrum beta-lactamases(ESBLs)positive strains were detected by DDST test.The association between ESBLs-producing strains and biofilm formation was significantly increased(χ2=4.448,P=0.035)compared with those that ESBLs-negative strains.Among 26 strains cephalosporinase(Amp C)-producing and 15 strains carbapenemases-producing,there was no significant difference between biofilm-positive and biofilm-negative strains,respectively.There was no inapparent difference in promoting biofilm formation between HM strains and non-HM strains.2.Fifty-three strains of β-lactamase resistance Klebsiella pneumoniae were screened.PCR results showed the strains were positive for ESBL-encoding genes: SHV(52,98.1%),TEM(35,66.0%),CTX-M-1 group(22,41.5%),CTX-M-2 group(30,56.6%),CTX-M-8 group(40,75.5%)group,CTX-M-9 group(21,39.6%)and CTX-M-25 group(2,3.8%),carbapenemase genes: KPC(13,24.5%),NDM(5,9.4%),VIM(5,9.4%),and Amp Cs genes: DHA(24,45.3%),EBC(3,5.7%).The virulence factors included capsular serotype K1(2,3.8%),K2(2,3.8%),K5(1,1.9%).Virulence genes including mrk D(53,100.0%),fim H(47,88.7%),ybt S(28,52.8%),rmp A(10,18.9%),ent B(5,9.4%),all S(4,7.5%),and aerobactin(2,3.8%).The results of MLST showed that there were 31 different ST types in 53 isolates,and eight strains(15.1%)were ST11,which was the dominant sequence type.Two new ST types were assigned as ST5214 and ST5215.Conclusion: The strain of hypermucoviscous Klebsiella pneumoniae had low resistance to a variety of antibiotics.MDR and ESBL-producing strains were more likely to form biofilms.In this study,Klebsiella pneumoniae carried a high frequency and diversity ofβ-lactamase genes and virulence factors,and these strains had high antibiotic resistance.