摘要：One of the most dangerous respiratory diseases is pneumonia, one of the ten leading causes of death globally. Hospital-acquired pneumonia (HAP) is a common infection in hospitals, which is the second most common nosocomial infection and causes inflammation parenchyma. In Community-acquired pneumonia (CAP), we have various risk factors, including age and gender, and also some specific risk factors. Ventilator-associated pneumonia (VAP) is one of the deadliest nosocomial infections. According to the Centers for Disease Control and Prevention, VAP is pneumonia that develops about 48 hours of an artificial airway. Bacteria, viruses, parasites, fungi, and other microorganisms can cause these diseases. This review article discusses microbial agents associated with pneumonia. Our goal is to gather information about HAP, CAP, and VAP to give people specific information. In this study, these three issues have been examined together, but in similar studies, each of them has been examined separately, and our type of study will be more helpful in diagnosis and treatment.
