| Objective:The aim of our study is to investigate the prevalence and possible mechanism of Carbapenem-resistant Klebsiella pneumoniae.Methods:Totally 835 strains of Klebsiella pneumoniae were isolated from January 2018 to January 2019 in Shanxi Bethune Hospital of Shanxi Academy of medical sciences(formerly known as Shanxi Dayi Hospital),and 41(4.91%)of them were identified as CRKP.CRKP strains were identified by MALDI-TOF MS combined with Vitek-2Compact automatic microbial analysis system.The full-automated microbiological analysis system(Vitek-2 Compact 60)for drug sensitivity analysis and the disk diffusion method(KB method)for supplementary drug sensitivity test.m CIM and e CIM tests screened the carbapenemase phenotypes;Detection of carbapenemase resistant genes(such as bla KPC,bla GES,bla IMP,bla VIM,bla NDM,bla OXA-48,etc.)and outer membrane channel protein genes(Ompk 35 and Ompk 36))in resistant strains by PCR.At the same time,gene sequencing was performed on the positive amplification products,and the presence and expression of outer membrane proteins were detected using RT-PCR.Results:1.A total of 835 strains of Klebsiella pneumoniae were isolated from the hospital,of which 41 strains(4.91%)were identified as CRKP.The patients from the isolates were mainly concentrated between 21-80 years old,with the highest isolation rate between41-50 years old,which was 24.39%(10/41);24.39%(10/41)were isolated from ICU specimens;31.71%(31/41)were isolated from sputum,19.51%(8/41)were urine,and19.51%(8/41)were blood.2.41 resistant strains were selected from 835 Klebsiella pneumoniae strains.The drug sensitivity test results showed that the resistance rates to imipenem and ertapenem were90.24%(37/41)and 100.00%(41/41)respectively;Cefazolin,cefoxitin and ceftriaxone were 100.00%;aztreonam was 97.56%(40/41);The resistant rates of ciprofloxacin and levofloxacin were over 90%.The resistance rates to amikacin,gentamicin and tobramycin were relatively low,56.10%(23/41),73.17%(30/41),and 73.17(30/41),respectively.3.For 41 strains of CRKP included in the study,the modified carbapenem inactivation test(m CIM)and the EDTA-modified carbapenem inactivation test(e CIM)phenotypic experiment were performed.The results showed that 31 strains(75.61%)shown as serinase,3 strains(7.32%)were metalloenzymes,7 strains(17.07%)were negative;molecular tests revealed 39 strains(95.12%)of carbapenemase resistance genes detected bla KPC type,1strain(2.44%)of bla NDM type,1 strain(2.44%)have both bla KPC and bla NDM genotypes;only 1(2.44%)of outer membrane channel protein lacks Ompk 36 gene,and the rest are present Ompk 35 and Ompk 36.Further analysis showed that only 9(21.95%)of 41 of Ompk 35 had down-regulated expression,while 40 of Ompk 36 had 38(95.00%)of down-regulated expression.Conclusion:1.The isolation rate of carbapenems resistant Klebsiella pneumoniae in our hospital is relatively high,mainly concentrated in the intensive care unit.This kind of bacteria presents the phenomenon of multiple drug resistance,and the trend of drug resistance becomes increasingly serious.Therefore,it is of vital importance to strengthen the infection control of key departments to control the spread of drug-resistant strains in the hospital.2.The drug resistance mechanism of clinically isolated Klebsiella pneumoniae was mainly bla KPC-producing enzyme combined with Ompk 36 membrane pore protein decreased expression. |
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