Isolation of bacteria from respiratory tract samples of patients in intensive care units during the COVID-19 pandemic and their antimicrobial resistance patterns

Initially identified in the Wuhan province of China and spreading globally, COVID-19 not only presents with specific symptoms but can also lead to serious complications by affecting multiple systems. This has increased the necessity for patients to be admitted to intensive care units during their treatment process. The development of secondary infections in intensive care units and the extensive use of antibiotics contribute to the emergence of antimicrobial resistance. This study aims to identify the types of microorganisms isolated from lower respiratory tract samples obtained from intensive care units during the Covid-19 pandemic and to determine the antimicrobial resistance rates of these microorganisms. Between March 2020 and February 2022, a total of 265 lower respiratory tract samples from patients in intensive care units were retrospectively analyzed at the Medical Microbiology Laboratory of Tokat Gaziosmanpaşa University Hospital. The identification of bacteria and their antibiotic susceptibility were performed using both conventional methods and the automated VITEK 2 system (bioMérieux/France). Bacterial growth was identified in a total of 258 samples, with the predominant pathogen being Acinetobacter baumannii (%42.6). Other bacteria isolated were Pseudomonas aeruginosa (18.6%), Staphylococcus aureus (16.7%), Klebsiella pneumoniae (11.6%), Escherichia coli (6.6%), Stenotrophomonas maltophilia (1.9%) and Streptococcus pneumoniae (1.9%). For Acinetobacter baumannii, resistance to carbapenems, cephalosporins, tetracyclines and fluoroquinolones was generally detected. The Pseudomonas aeruginosa isolates exhibited maximum resistance to piperacillin at a rate of 39.6%, while showing high-dose sensitivity to aztreonam at a rate of 62%. Among 43 Staphylococcus aureus isolates, 13 were identified as Methicillin-resistant (MRSA) and 30 as Methicillin-sensitive (MSSA). Staphylococcus aureus demonstrated the highest resistance to penicillin at a rate of 83.7%. In this thesis, the distribution of pathogens isolated from lower respiratory tract samples sent from intensive care units to our hospital's laboratory between March 2020 and February 2022, as well as their antimicrobial resistance profiles, have been identified. The obtained data show that isolates such as Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa exhibit high levels of resistance to multiple antibiotic groups. The data obtained is expected to contribute to the development of hospital infection control policies and the optimization of treatment protocols. Key Words: Lower respiratory tract samples, antimicrobial resistance, COVID-19