[The distribution of microorganisms and antibiotic resistance profile in pulmonary critical care unit patients: A single-centre study].

Introduction: The patients in the intensive care unit have a higher risk of infections because of the poor general condition of these patients and the frequent application of invasive procedures with longer hospitalization length. Also, this group of patients tend to have resistant infections due to empirically widespread and uncontrolled use of broad-spectrum antibiotics. Hence, data are needed to determine appropriate empirical antibiotic therapy in intensive care patients. In this study, it was aimed to assess the distribution of microorganisms and antibiotic resistance profile from the samples taken from the patients in the intensive care unit.

Materials And Methods: Patients who were hospitalized in Ankara University Faculty of Medicine Chest Diseases Intensive Care Unit for more than 24 hours between December 2016 and December 2017 were included in our study. Demographic characteristics, comorbid diseases, clinical findings, results of sputum, tracheal aspirate, blood, urine, gaita and pus culture samples and antibiotic susceptibility test results were recorded prospectively.

Result: A total of 287 patients, 150 males and 137 females, were included in the study. The mean age of all patients was 69.96 ± 14.4 years. Two hundred twenty-three positive cultures were detected in 1053 samples taken from 287 patients. Gram-negative bacilli constituted 55.1% of the 223 positive cultures. The most common microorganisms were Acinetobacter (16.6%), Staphylococcus (14.8%) and Klebsiella (10.8%). Colistin resistance was found to be 8.3% in the Acinetobacter strains and resistance rates of 97-100% were observed to other antibiotic groups. Thirty-three staphylococcus were isolated, 17 were S. aureus and 16 were coagulase-negative Staphylococcus. While 29.4% of S. aureus were resistant to methicillin (MRSA), vancomycin resistance was not detected. Meanwhile, the MRSA ratio was 62.5%, there was no vancomycin resistance among the coagulase-negative Staphylococcus. Klebsiella was the third most common microorganism and beta-lactamase producing Klebsiella strain was 62.5%. Gentamycin was found to be the most susceptible antibiotic in Klebsiella strains with a resistance rate of 20.8%. Pseudomonas aeruginosa constituted 9.4% of the cultures. While the resistance to colistin was not detected, resistance to piperacillin/tazobactam 42.8%, tobramycin, imipenem and meropenem 50% and ceftazidime 61.9%. The duration of hospitalization in patients with Acinetobacter isolated (23 [10-34] days vs 12.5 [5-24] days, p= 0.011) and the mortality rate (62.5% vs 37.5%, p= 0.008) were significantly higher than those who were not Acinetobacter isolated.

Conclusions: In conclusion, gram-negative bacilli constitute the majority of the patients in intensive care unit. Acinetobacter, the most common microorganism, has a high resistance rate and has been associated with prolonged hospitalization and mortality.