Introduction: Hospitalized patients are at risk to develop sepsis from infections due to colonized intravenous lines, surgical wounds, and/or bedsores. Multidrug resistant Acinetobacter commonly colonizes patients in the intensive care unit (ICU) and can cause serious infections. The APACHE II severity score has shown a good calibration and discriminatory value across a wide range of disease processes, and remains the most commonly used international severity scoring system worldwide. Aim of work: to evaluate the patients having different types of hospital-acquired infections in the medical ICU, especially infections caused by multidrug resistant organisms (as Acinetobacter spp.), in a specific period of time, applying the APACHE II scoring system of severity. Materials and methods: The study included 148 patients from the medical ICU in Cairo University Hospital. Routine laboratory investigations were done together with chest X-rays, ECG, abdominal ultrasound and bacterial cultures,and APACHE II scores were calculated for all patients. Results: We found that the most
common cause of death in ICU patients in our study was sepsis (48% of all deaths). Most frequently reported isolated organisms were Klebsiella spp. (24.4%), E-coli (21.8%), and Acinetobacter spp. (17.1%). There was a meaningful association between observed mortality rates in patients in ICU and their APACHE II score evaluation, so APACHE
II score had a strong positive correlation with actual mortality rate. Conclusion: Sepsis was the cause of high mortality rates in medical ICU, and the most important step in the prevention and control of infection in the ICU is continuous application of effective infection control measures.