Background: The control of infections in intensive care units (ICUs) is becoming more difficult.Antibiotics utilization Recent antibiotic overuse has prompted the emergence resistance to antibiotics, which poses a threat to healthcare, especially in developing nations without access to antibiogram in most ICUs. Objectives: This study aimed to present antibiotic susceptibility pattern of microbial infections and describe some antibiotic use features. Patients and method: This is a cross sectional study included 53 patients with lower respiratory tract infections admitted in respiratory ICU chest department, University Hospitals of Zagazig in the period from September 2018 to September 2019, we collected the following data: past history, length of hospital stay and comorbidities. The following parameters were assessed: clinical pulmonary infection score (CPIS), general and local examination, radiological and routine laboratory investigation, arterial blood gases (ABG) and microbiological results of isolated microbes and their susceptibility pattern using (blood and sputum culture). Result: Among studied patients one patient died during the study and excluded, mean age was 56.48±15.73, 53.8% were males and 46.2% were females. 36 (69.23%) were improved,16 (30.77%) were complicated. Blood and sputum culture were done for all patients most organism detected in sputum culture was Klebsiella pneumonie, in blood culture was Staphylococcus aures. According to culture towards Klebsiella, highest sensitivity was levofloxacin (93.33%), Streptococcus pneumoniae highest sensitivity was levofloxacin (83.33%), Staphylococcus aureus highest sensitivity was linezolid (85%), Pseudomonas aeruginosa. highest sensitivity was meropenem (83.33%), Acinetobacter highest sensitivity was imepenem (58%). Conclusion: Combined clinical, laboratory, radiological and microbiological findings help in diagnosis and treatment of LRTI.