Detection of carbapenem resistance in ESBL-positive and carbapenemase-producingklebsiella pneumonia strains using phenotypic and molecular methods

Antimicrobial resistance is a serious health problem in the world and in our country. Carbapenem-resistant Klebsiella pneumoniae is at the top of the World Health Organization's 2024 list. K. pneumoniae is an infectious agent that causes significant mortality and morbidity in ICU patients. Carbapenem-resistant and ESBL-positive K. pneumoniae strains grown in respiratory tract and blood samples of patients hospitalized in ICUs were included in this thesis study. It was aimed to investigate the resistance-inducing enzymes KPC, NDM, OXA- 48 and VIM by PCR method. The study included respiratory tract (endotracheal aspirate, broncho-alveolar lavage, sputum, etc) and hemoculture samples of 75 patients hospitalized in the Intensive Care Units of Cerrahpaşa Medical Faculty Hospital in 2023. In addition, to conventional culture methods (Blood agar, chromoagar, MIO medium), Vitek 2 Compact (Biomerieux) and Maldi-Tof (Bruker) automated systems were also used to identify of K. pneumoniae isolates. The grown bacteria were stored in tryptic soy broth agar medium in a -80 ° C deep freezer until the day 18 of the study. Then, these storage samples were passaged and the grown K. pneumoniae isolates were first subjected to extraction. Then, the resistance-inducing KPC, NDM, OXA-48 and VIM enzymes were investigated by Real Time PCR method in each separate experiment. Of 75 patients, 47 (62.7%) were male and 28 (37.3%) were female. The age range of the patients ranged from 20 to 93 (62.56 ± 18.29) years. 42 (56%) of the samples were respiratory tract samples (BAL, ETA, sputum, etc.) and 33 (44%) were hemoculture samples. From the carbapenem group, imipenem was determined as 52.0% resistant, 48.0% susceptible; meropenem was determined as 90.7% resistant, 9.3% susceptible. The rates of carbapenemase enzymes were determined as NDM 92%, OXA-48 84%, KPC 81.3% and VIM 78.7%. The co-occurrence of carbapenemase enzymes; The presence of KPC+OXA-48+NDM+VIM was found to be 70.7%, OXA-48 + NDM was found to be 8.0%, KPC+OXA-48+NDM was found to be 5.3%, KPC+NDM+VIM was found to be 5.3%. VIM was found to be 2,7% and NDM alone was found to be 2,7%. None of the enzymes investigated were detected in the four samples (5.3%). When examined according to gender, being under and over 60 years of age and the ICU where the patient was admitted; no statistically significant difference was found in terms of the presence of carbapenemase enzyme (p>0.05). It is necessary to be careful about ICU infections caused by carbapenemase-producing bacteria. We believe that it is important for hospitals to conduct cross-sectional surveillance for carbapenemase-producing bacteria at regular intervals.