Manifestations of Infection: Signs and symptoms vary according to the site and severity of infection Diagnosis requires a composite of information, including history physical examination, radiographic findings, and laboratory data a Microbial Causes of Infection: Infections may be caused by bacteria, viruses, fungi, and parasites. The pathogen may be exogenous (acquired from environmental or animal sources or from other persons or endogenous (from the normal flora)Manifestations of Infection: Signs and symptoms vary according to the site and severity of infection. Diagnosis requires a composite of information, including history, physical examination, radiographic findings, and laboratory data. Microbial Causes of Infection: Infections may be caused by bacteria, viruses, fungi, and parasites. The pathogen may be exogenous (acquired from environmental or animal sources or from other persons) or endogenous (from the normal flora)