Nearly half of intensive care unit (ICU) patients have an infection at any given time, and almost 70% are treated with antibiotics. Severe infection is a common indication for ICU admission, and once admitted to the ICU, patients are exposed to a variety of interventions (including intubation, catheterization, and antibiotics) that predispose them to subsequent infection. Given the high prevalence of infections in the ICU, familiarity with diagnosis and management of the most common types of infection is crucial for any ICU provider. In this chapter, we review several common infectious syndromes encountered in the ICU (including catheter-related bloodstream infection, pneumonia, and C. difficile infection) with a focus on antimicrobial management.