Inclusion Criteria:  Patients of 18 years of age and above A clinical suspicion of VAP as defined in the American Thoracic Society (ATS) guidelines A Clinical Pulmonary Infection Score (CPIS) > 6 No signs and symptoms of infection at the time of admission to the ICU  Exclusion Criteria:  Acute kidney injury Renal replacement treatment (RRT) Dialysis Renal transplantation Active tuberculosis Malnutrition Immunosuppression (neutropenia, HIV positivity, transplantation, prednisone treatment of ≥20 mg/day, etc.) Any extrapulmonary infection other than VAP at the time of being included in the study Respiratory cultures presented fungal agents Normal flora No growth