For diagnosing Pneumocystis jirovecii in an immunocompromised patient, which specimen is preferred?

Induced sputum is the preferred specimen for diagnosing Pneumocystis jirovecii, especially in immunocompromised patients. This is largely due to the fact that Pneumocystis jirovecii primarily causes pneumonia, and obtaining a sample of respiratory secretions can provide a direct means to detect the organism. The induced sputum procedure involves inhaling a saline mist, which helps to mobilize secretions from the lungs, allowing for a better chance of collecting an adequate sample where the fungus resides.

Analyzing this selection further, open-thorax lung biopsy, while it can yield definitive results, is an invasive procedure that carries greater risks and is typically not the first choice for diagnosis due to potential complications and the need for hospitalization. Cerebrospinal fluid (CSF) is not relevant for this type of fungal infection as Pneumocystis jirovecii primarily affects the lungs, making it an unlikely specimen for diagnosis. Urine sampling does not typically yield useful results for diagnosing this particular organism, as Pneumocystis jirovecii does not commonly appear in urine.

In summary, induced sputum is non-invasive, specifically targets the primary site of infection, and is an effective method for identifying Pneumocyst