Hospital-acquired pneumonia, also known as nosocomial pneumonia, refers to pneumonia contracted within 48-72 hours of hospitalization and is commonly caused by bacterial infections. It is easy for hospital patients to develop this type of pneumonia because they are generally ill with weakened immune systems. Certain patients are at higher risk, such as those over 70, having prior antibiotic treatments, or using ventilators. Hospital-acquired pneumonia can be difficult to treat due to the variety of bacteria that may cause it, and physicians may perform bronchoscopy to determine the specific bacteria to select the proper antibiotic treatment.