Background: This study aimed to evaluate antibiotic resistance genes and virulence genes and the clonal relationship of the carbapenem-nonsusceptible Klebsiella pneumoniae strains by molecular methods which are isolated from various clinical specimens from patients treated in tertiary care hospital in Turkey. Methods: Identification of 32 carbapenem non-susceptible K. pneumoniae were determined by VITEK-2 (BioMérieux, France) automated system. Thirteen colistin-resistant strains were tested with the broth 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 among these strains. Results: PCR demonstrated that 31 of the strains carried at least one of the carbapenemase genes. In one strain, the coexistence of bla_OXA−48+NDM was shown. The most common resistance genes were determined as bla_SHV (84.3%), bla_CTX−M−1 (46.8%), bla_OXA−48 (40.6%), bla_KPC (40.6%), bla_TEM (31.2%), bla_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. All colistin-resistant isolates were also found to be resistant by colistin broth microdilution. In PFGE analysis, 25 different genotypes were determined and clustering isolates were collected in 5 different clusters and the clustering rate was 35.4%. 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. In MALDI-TOF MS typing, the maximum similarity between the strains was less than 70% and clustering not shown. 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 our region. ST101 type was determined as the most common type between the strains. To the best of our knowledge, this is the first study that compares these three methods in our country. There may be differences between bacterial identifications made with VITEK-2 and MALDI-TOF MS. In this study, it was observed that MALDI-TOF MS analyses were not compatible with the typing of strains according to PFGE and MLST analysis results.

Background: Emerging carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) (CRKP) bacteremias are presenting significant public health risks due to limited treatment options and increased mortality. K. pneumoniae isolates exhibit carbapenem resistance rates that vary from 25% to 50% throughout the European continent, including our country. Aims: To assess the characteristics of CRKP bacteremia, a condition that has recently demonstrated an increasing prevalence in our center. We sought to ascertain the resistance rates of isolated strains to antibiotics other than carbapenems, identify the responsible carbapenemase genes, evaluate the efficacy of antibiotics, determine mortality rates, explore clonality among strains, and investigate the influence of the COVID-19 pandemic on all these factors. Study Design: Retrospective observational study. Methods: This study included patients aged 18 and older who had experienced meropenem-resistant K. pneumoniae bacteremia. Meropenem resistance was confirmed by employing the Kirby-Bauer disk diffusion method. Meropenem minimum inhibitory concentration (MIC) levels were determined using the gradient test, while colistin MIC levels were ascertained using the disk elution technique. Carbapenemase genes were evaluated via colony polymerase chain reaction (PCR), and clonality analysis was performed using the arbitrarily primed PCR technique. Results: The study comprised 230 patients, with a mean age of 63.1 +/- 15.9 years, of whom 58.7% were male. Oxacillinase-48 (OXA-48) was detected in 74.8% of the patients, New Delhi metallo-beta-lactamase (NDM) in 12.6%, OXA-48 + NDM in 7.8%, and KPC in 4.8%. The 14-day and 30-day mortality rates were 57% and 69.6%, respectively. Multivariate analysis of the 30-day mortality revealed several crucial factors, including bacteremia development in the intensive care unit, the occurrence of bacteremia during the COVID-19 pandemic, polymicrobial bacteremia, the use of indwelling intravenous catheters, a platelet count of <= 140,000/ mu l, procalcitonin levels of >= 6 mu g/l, and a Charlson comorbidity score >= 3. Notably, the OXA-48 and KPC genes were upregulated significantly during the COVID-19 pandemic, while the NDM gene groups were downregulated. Additionally, both 14-day and 30-day mortality rates increased significantly. Conclusion: In this study, the most prevalent carbapenemase gene was OXA-48; however, there has been a recent increase in KPC genes. No dominant epidemic strain was identified through clonality analysis. The clustering rate was 68% before the pandemic, increasing to 85.7% during the pandemic. The significance of infection control measures is underscored by the rise in both clustering and mortality rates during the COVID-19 pandemic.

Due to underrepresentation of carbapenemase-producing Enterobacterales infections in randomized controlled trials with ceftazidime-avibactam (CZA) and high cost of CZA therapy, other appropriate antimicrobial therapies (OAAT) are still being used for OXA-48- or KPC-producing Enterobacterales infections in Türkiye. We conducted a multicentre retrospective 1:1 matched cohort study of patients who received ≥48 h of CZA or OAAT for documented OXA-48- or KPC-producing Enterobacterales infections. Patients were matched based on (1) the number of days (± 1 d) from the infection onset to the initiation of therapy, (2) INCREMENT-CPE score (± 1), (3) source of infection, (4) year of infectious episode, and (5) type of causative microorganism. From 5 Turkish university hospitals, 180 patients were enrolled. Baseline characteristics were all similar between treatment groups. At the time of treatment initiation, 63.9% of patients were in the intensive care unit, 35.6% had septic shock and 41.1% required mechanical ventilation support. Thirty-day mortality occurred in 35.6% (32/90) of patients treated with CZA and in 56.7% (51/90) of those receiving OAAT regimens (P = 0.004). Twenty-one-day clinical response was seen in 50% (45/90) and 26.7% (24/90) of patients receiving CZA and OAAT, respectively (P = 0.002). In multivariable logistic regression analyses, CZA treatment was associated with less likelihood of mortality (aOR = 0.37; 95% CI: 0.19-0.71; P = 0.003) and higher likelihood of 21-d clinical response (aOR = 3.32; 95% CI: 1.68-6.53; P < 0·001). Treatment with CZA is associated with more favourable clinical outcomes in treatment of OXA-48- or KPC-producing Enterobacterales infections. A randomized controlled trial is needed to confirm these results.