<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 44-year-old man, with a history of intravenous IV drug use, presented to the emergency department due to worsening non-productive cough, exertional dyspnea, and night sweats. His cough started 3 weeks ago and progressively worsened. He is homeless and well-known by the hospital staff. He was previously admitted to the hospital after an overdose of opioids. He takes no medication. At the hospital, the vital signs included: blood pressure 10168 mm Hg, heart rate 99min, respiratory rate 20min, oxygen saturation of 91 on room air, and oral temperature of 37.4C 99.3F. His chest X-ray showed left perihilar shadowing. The laboratory results included:WBC count 8,800mm3Arterial pH 7.39Rapid HIV testing positive with an elevated viral loadPaCO2 41 mm HgPaO2 76 mm HgHe was admitted for the treatment of presumed sepsis and pneumonia, and he was immediately started on IV ceftriaxone. An induced sputum specimen shows multiple kidney bean-shaped cysts that are approximately 5 um. These cysts stain positive with methenamine silver. What is the preferred antibiotic therapeutic regimen for this condition?? A: Isoniazid, rifabutin, pyrazinamide and ethambutol, B: Intravenous liposomal amphotericin B with flucytosine, C: Fluconazole with flucytosine, D: Trimethoprim-sulfamethoxazole, E: Clindamycin and primaquine, with adjunctive prednisone,  <response>: Based on the information provided in the question stem, this patient is a 44-year-old IV drug user with worsening cough, dyspnea, night sweats, and low oxygen saturation. He was admitted for presumed sepsis and pneumonia. His chest X-ray showed perihilar shadowing and his sputum sample stained positive for 5 um kidney bean-shaped cysts using methenamine silver stain. The positive methenamine silver stain indicates this is likely Pneumocystis jirovecii formerly P. carinii pneumonia. P. jirovecii is an opportunistic fungus that causes pneumonia in immunocompromised patients, especially HIVAIDS. The treatment of choice for P. jirovecii pneumonia is trimethoprim-sulfamethoxazole TMP-SMX. Other options include clindamycin primaquine or intravenous pentamidine. But TMP-SMX is preferred due to its efficacy and availability.The other answer choices are for treatment of tuberculosis, cryptococcal meningitis, and histoplasmosis which do not fit the clinical presentation.D: Trimethoprim-sulfamethoxazole 