A 53-year-old woman with long-standing rheumatoid arthritis comes to the emergency department due to seizures. She has had cough, fever, and night sweats for the past 2 weeks. She is on immunosuppressive therapy for her rheumatoid arthritis. Her temperature is 38.9 C (102 F), blood pressure is 120/76 mm Hg, pulse is 80/min, and respirations are 16/min. Physical examination shows scattered rales in both lung fields. CT scan of the chest shows multiple nodules. CT scan of the brain shows left temporal lobe abscess. Bronchoalveolar lavage cultures grow partially acid-fast, gram-positive, branching rods. Which of the following is the most effective treatment for this patient?

Question

A 53-year-old woman with long-standing rheumatoid arthritis comes to the emergency department due to seizures.  She has had cough, fever, and night sweats for the past 2 weeks.  She is on immunosuppressive therapy for her rheumatoid arthritis.  Her temperature is 38.9 C (102 F), blood pressure is 120/76 mm Hg, pulse is 80/min, and respirations are 16/min.  Physical examination shows scattered rales in both lung fields.  CT scan of the chest shows multiple nodules.  CT scan of the brain shows left temporal lobe abscess.  Bronchoalveolar lavage cultures grow partially acid-fast, gram-positive, branching rods.  Which of the following is the most effective treatment for this patient?

Quizplus · Accepted Answer

This immunocompromised patient has systemic symptoms, lung nodules, and brain abscess (causing seizures), and the cultures grow gram-positive, partially acid-fast, filamentous, branching rods. This finding is highly consistent with Nocardia. Nocardiosis classically affects immunocompromised hosts and may initially be confused with tuberculosis. Systemic symptoms such as weight loss, fever, and night sweats are common. Chest x-ray findings include alveolar infiltrates and nodules, often with cavitation. Nocardia can disseminate from the lungs to affect other organs, with the brain or the skin being the most common. The treatment of choice for pulmonary nocardiosis is trimethoprim-sulfamethoxazole. When the brain is involved, the carbapenems are added for better coverage. When possible, abscesses should be surgically drained as well. Duration of therapy depends on the clinical response but is generally long (6-12 months). (Choice A) Aztreonam is a monobactam antibiotic used to treat gram-negative bacterial infections, including Pseudomonas aeruginosa. It is not effective against gram-positive organisms such as Nocardia. (Choice B) Clindamycin is often used to treat pulmonary abscess due to aspiration pneumonia, in which the causative organisms are anaerobic oral flora. It does not have good activity against Nocardia species. (Choice C) Isoniazid, rifampin, and ethambutol are used to treat tuberculosis. This patient's clinical presentation is consistent with tuberculosis, but Mycobacterium tuberculosis would appear on microscopy as acid-fast rods that do not Gram stain (as opposed to the gram-positive, partially acid-fast rods of Nocardia). (Choice D) Penicillin G is the treatment of choice for Actinomyces, another filamentous gram-positive bacterium. Actinomycosis may present similarly to nocardiosis, but there are several key differences: Actinomyces is anaerobic, not aerobic; Actinomyces is not acid-fast; and sulfur granules may be found with Actinomyces infection. (Choice F) Voriconazole would be the treatment of choice for aspergillosis, another common cause of pulmonary abscess in the immunocompromised host. Antifungal agents have no activity against Nocardia. Educational objective: Nocardia is a filamentous, aerobic, gram-positive bacteria that is partially acid-fast. It causes pulmonary or disseminated disease (particularly to the brain) in immunocompromised hosts. The treatment of choice is trimethoprim-sulfamethoxazole. References: Current treatment for nocardia infections. (http://www.ncbi.nlm.nih.gov/pubmed/24093436) Susceptibility profiles of Nocardia isolates based on current taxonomy. (http://www.ncbi.nlm.nih.gov/pubmed/24247124)

A 53-Year-Old Woman with Long-Standing Rheumatoid Arthritis Comes to the Emergency