Research of Klebsiella pneumoniae Heteroresistance to Cephalosporin
Klebsiella pneumoniae(KP)often causes clinical bacterial infections,and its heteroresistance(HR)to antibiotics often leads to treatment failure.To provide a reference for the clinical treatment of bacterial infections,the heteroresistance of K.pneumoniae to cephalosporin antibiotics was studied in this article.Col-lect 100 clinical isolates of K.pneumoniae.Heteroresistance characteristics of KP were investigated by the microdilutionbroth method,Kirby Bauer(K-B)disk diffusion method,population analysis profile(PAP),resis-tance stability test,and fitness cost experiment.The resistance rates of KP to Ceftazidime(CAZ)and Cefepime(FEP)were 23％and 25％,respectively,determined by the microdilution broth method.According to the K-B method,the heteroresistance rates of KP to CAZ and FEP were 33％and 23％,respectively.The PAP test con-firmed nine FEP heteroresistant strains,accounting for 9％of the total experimental strains.The frequency of resistant subpopulations was 1×10-6-4×10-2.After 50 generations of passage without antibiotic pressure,the re-sistance level of the heteroresistant strain KS38 resistant subpopulations reverted to a certain degree,while the resistance level of the heteroresistant strain KR9 resistant subpopulations remained stable.The fitness cost ex-perimental results showed that the KS38 resistant subpopulations grew faster than the parental strain(4-8 h),with significant differences(P＜0.05).There was no statistical difference(P＞0.05)in the growth rates of heterore-sistance subpopulations of KR9 and its parental strain.In this study,the heteroresistance rate of K.pneumoni-ae to cephalosporin antibiotics was relatively low,but the frequency of resistant subpopulations was relatively high.The resistance levels of the resistant subpopulations remain at clinical resistance levels after passage for 50 generations,though their resistant stability varies.Moreover,the resistant subpopulations did not show fit-ness costs.Therefore,to prevent the emergence of higher levels of resistance bacterial subpopulations that lead to clinical treatment failure,more attention should be paid to the occurrence of heteroresistance when using cephalosporin antibiotics for the treatment of K.pneumoniae infections.
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