A patient who is positive for pneumocystis carinii pneumonia should be treated with which agent?

The treatment of choice for a patient with pneumocystis carinii pneumonia (PCP), now known as Pneumocystis jirovecii pneumonia, is nebulized Pentamidine (Nebupent). This medication is an antimicrobial agent specifically indicated for the treatment and prophylaxis of PCP, particularly in immunocompromised patients, such as those with HIV/AIDS.

Pentamidine works by inhibiting the synthesis of nucleic acids and proteins in the pathogens, effectively targeting the organism causing the pneumonia. Its administration via nebulization allows for localized delivery to the lungs, where the infection occurs, enhancing its therapeutic effect while minimizing systemic side effects.

Other options listed, such as aerosolized atropine and inhaled tobramycin, do not have efficacy against Pneumocystis jirovecii and are utilized in different clinical scenarios—atropine primarily manages bronchospasm, and tobramycin is an antibiotic typically used against bacteria, particularly in cases of cystic fibrosis. Bronchoalveolar lavage with normal saline is a diagnostic and procedural tool rather than a treatment, and while it may help in sampling fluids for analysis, it does not provide therapeutic effects against the infection itself. Therefore, nebulized Pentamidine stands