A 32-year-old woman comes to the emergency department due to 4 weeks of worsening cough, shortness of breath, and low-grade fevers. She also has had an unintentional weight loss of 4.5 kg (10 lb) over the past 3 months. Temperature is 37.1 C (98.8 F), blood pressure is 120/70 mm Hg, pulse is 102/min, and respirations are 22/min. Pulse oximetry shows 86% on ambient air. Lung auscultation reveals bilateral crackles. There are no heart murmurs, and jugular venous pressure is normal. Chest x-ray reveals diffuse interstitial infiltrates. The patient undergoes bronchoscopy; methenamine silver staining of the bronchoalveolar lavage specimen is shown in the image. Which of the following is the most appropriate pharmacotherapy for this patient's current condition?

Question

A 32-year-old woman comes to the emergency department due to 4 weeks of worsening cough, shortness of breath, and low-grade fevers.  She also has had an unintentional weight loss of 4.5 kg (10 lb) over the past 3 months.  Temperature is 37.1 C (98.8 F), blood pressure is 120/70 mm Hg, pulse is 102/min, and respirations are 22/min.  Pulse oximetry shows 86% on ambient air.  Lung auscultation reveals bilateral crackles.  There are no heart murmurs, and jugular venous pressure is normal.  Chest x-ray reveals diffuse interstitial infiltrates.  The patient undergoes bronchoscopy; methenamine silver staining of the bronchoalveolar lavage specimen is shown in the image.  Which of the following is the most appropriate pharmacotherapy for this patient's current condition?

Quizplus · Accepted Answer

11ec160b_38a1_ed55_9249_05a878e6547c_MD0001_00 Pneumocystis pneumonia is an AIDS-defining illness that is often seen in patients who were previously unaware of HIV infection. The underlying pathogen is an atypical fungus called Pneumocystis jirovecii. Healthy patients rapidly clear the inhaled organisms, but those with impaired cell-mediated immunity are at risk for a noninvasive infection that fills the alveoli and leads to slowly worsening pulmonary symptoms (eg, dry cough, shortness of breath), hypoxia, and a diffuse, bilateral interstitial infiltrate. Fever and weight loss are also usually present. P jirovecii cannot be cultured; therefore, definitive diagnosis requires identification of the organism in respiratory secretions. Methenamine silver stain is frequently used to identify the cell wall of the pathogen, which often appears as a crescent, a crushed ping-pong ball, or a circular ring around a clear center. First-line treatment with trimethoprim-sulfamethoxazole is usually curative. (Choice A) Invasive pulmonary aspergillosis may be treated with caspofungin and is most common in patients with severe immunosuppression (eg, AIDS, neutropenia). It usually presents with fever, cough, chest pain, dyspnea, and hemoptysis. Silver stain can be used to diagnose aspergillosis, but numerous hyphae (not cystic organisms) will be seen. (Choice B) Ceftriaxone and azithromycin are often used to treat community-acquired bacterial pneumonia, which usually presents acutely with productive cough, fever, and shortness of breath. Chest x-ray typically reveals a lobar infiltrate rather than a diffuse interstitial infiltrate. (Choice C) Doxycycline can be used to treat Mycoplasma pneumonia, which often presents with several weeks of incessant cough and chest x-ray showing interstitial infiltrates. However, significant hypoxia is uncommon, and M pneumoniae is not identified on silver stain. (Choice D) Patients with advanced AIDS are at risk for cytomegalovirus (CMV) pneumonia, which is treated with ganciclovir and can cause fever, cough, dyspnea, and diffuse pulmonary infiltrates. The presence of "owl's eye" inclusion bodies on histopathology strongly supports a CMV infection. (Choice F) Vancomycin inhibits cell wall synthesis and is primarily used for severe or drug-resistant, Gram-positive bacterial infections such as methicillin-resistant Staphylococcus aureus. Educational objective: Pneumocystis pneumonia is common in patients with advanced HIV and usually presents with slowly worsening cough and dyspnea, hypoxia, and bilateral interstitial infiltrates. Diagnosis requires visualizing the organism in respiratory secretions using special stains (eg, methenamine silver stain). First-line treatment is trimethoprim-sulfamethoxazole.

A 32-Year-Old Woman Comes to the Emergency Department Due to 4