Final answer:
PCP is diagnosed with a CXR showing ground glass infiltrates in a patient on immunosuppressants and is caused by the fungus Pneumocystis jirovecii. Microscopic exams and PCR-based tests are used for diagnosis, and TMP/SMZ is the primary treatment.
Step-by-step explanation:
Pneumocystis pneumonia (PCP) is diagnosed in a febrile patient taking high dose immunosuppressants when a chest x-ray (CXR) reveals diffuse bilateral (B/L) ground glass infiltrates. These infiltrates are indicative of PCP, a form of pneumonia caused by the fungus Pneumocystis jirovecii. Immunocompromised individuals, such as those with HIV/AIDS or those receiving chemotherapy, are particularly susceptible to this type of pneumonia.
PCP is typically identified through the microscopic examination of tissue and fluid from the lungs. Other diagnostic tools may include PCR-based tests, which can detect the fungus even in asymptomatic patients. The first-line treatment for PCP is the combination of trimethoprim-sulfamethoxazole (TMP/SMZ), which is a blend of antibiotics that can often have adverse effects. However, their benefits in treating PCP outweigh the risks.