Evaluating molecular epidemiology of carbapenem nonsusceptible klebsiella pneumoniae isolates with MLST, malditof, PFGE

Introduction and Purpose: This study aimed to evaluate antibiotic resistance genes and virulence genes and the clonal relationship of the carbapenem-nonsusceptible K.pneumoniae strains by molecular methods with epidemiological data which are isolated from various clinical specimens from patients treated at Recep Tayyip Erdogan University Training and Research Hospital. Materials and Methods: Thirty-two carbapenem non-susceptible K. pneumoniae isolates were included in the study with the VITEK-2 (BioMérieux, France) automated system. Thirteen colistin-resistant strains were tested with colistin microdilution method. Various antibiotic resistance genes and virulence genes frequently seen in carbapenem-resistant strains were screened by PCR. Immunochromatographic tests used in the rapid diagnosis of carbapenemases were compared with PCR results. In addition, PFGE, MLST and MALDI-TOF MS methods were used to determine the clonal relationship of carbapenemnonsuscetible K. pneumoniae strains isolated from our hospital. Results: For all strains, the highest resistance was demonstrated against TZP, CAZ, FEP and MEM. Gentamicin (78.1%) was found to be the most sensitive antibiotic. PCR demonstrated that 31 of the strains carried at least one of the carbapenemase genes. In one strain, the coexistence of OXA-48+NDM was shown. The most common resistance genes were determined as SHV (84.3%), CTX-M-1(46.8%), OXA-48(40.6%), KPC(40.6%), TEM(31.2%), NDM(18.8%) respectively. Among the virulence genes; magA (68.7%) was the most common, followed by kpn(59.3%) and K2(9.3%). Immunochromatographic tests were found to be 100% compatible with PCR results. According to the results of VITEK-2 automated system, all isolates found to be resistant to colistin were also found to be resistant by colistin broth microdilution. In PFGE analysis, it was shown that 19 of the isolates clustered in 6 different clusters according to the Tenover criteria, while the other isolates were found to be unrelated to each other. In MLST analysis, ST101 type was determined as the most common ST type with a rate of 29%. ST101 is followed by ST16, ST307, ST14, ST147, ST309, ST377, ST395 and ST2096, respectively. The compatibility rate between MALDI-TOF MS and VITEK-2 was found 94.3%, in bacterial identification. v As a result of the molecular typing evaluation, the maximum similarity between the strains was less than 70%. Conclusion: In addition to OXA-48, which is endemic in our country, it has been determined that KPC, which is more common in the world, is becoming increasingly common. In molecular typing, MLST and PFGE results were shown to be compatible. However, they were not compatible with MALDI-TOF MS. Among the molecular typing methods, PFGE is seen as the best method. There are differences between VITEK-2, MALDI-TOF MS and MLST in bacterial identification. Monitoring of carbapenemresistant bacteria by each institution in terms of infection control will contribute to rational antibiotic use policies and infection control measures to combat antibiotic resistance, which has become a global public health problem all over the world. Keywords: K. pneumoniae, carbapenem, PFGE, MLST, MALDI-TOF MS