Objectives: To examine whether there is a difference in the result of microbiological findings, the development of nosocomial infection and the outcome of treatment in neurosurgical and abdominal patients treated postoperatively at the Department of Intensive Care Medicine during 2020. Study design: cross-sectional study Subjects and methods: Disease histories, therapeutic lists, and microbiological findings of 140 neurosurgical and abdominal patients treated in the ICU during 2020 who were suspected of developing infection were analyzed. Age, sex, length of stay in the ICU, comorbidities, reoperations, hours of mechanical ventilation, type and result of microbiological sample, diagnosis of nosocomial infection and treatment outcome were compared. Results: It was found that the days of stay in the ICU and the hours of mechanical ventilation were significantly longer in neurosurgical patients (P < 0.001). No significant difference in the incidence of all nosocomial infections between the groups was observed. Acinetobacter baumannii was significantly more isolated in abdominal patients (P = 0.02), and Pseudomonas aeruginosa resistant to carbapenems (P < 0.001) in neurosurgical patients. No significant difference in the number of deaths was observed between the groups, but in abdominal patients there were significantly more deaths who developed nosocomial infection (P = 0.02). Conclusion: Although the ratio of isolated pathogenic bacteria does not differ, the proportion of predominant multidrug-resistant bacteria is different between neurosurgical and abdominal patients. The duration of stay and hours of mechanical ventilation are longer in neurosurgical patients. There was no significant difference in the development of nosocomial infection between the groups, nor in the outcome of treatment, but higher mortality was observed in abdominal patients diagnosed with nosocomial infection.