A 45-year-old man was diagnosed 1 month ago with a squamous cell lung cancer involving his left hilum and has been receiving chemotherapy. He is now admitted to the ICU with hypoxemia and fever. He reports about 10 days of low-grade fevers and loss of appetite, which has progressed to worsening shortness of breath and a cough productive of foul-smelling, purulent sputum. His chest radiograph demonstrates dense consolidation of his left lower lobe with evidence of an abscess. A computed tomography (CT) scan is ordered and he is started on vancomycin, cefepime, and metronidazole. Sputum cultures are pending.
Which of the following is the most accurate regarding his diagnosis?A. His current antibiotic regimen is appropriate
Correct Answer: A
The patient’s presentation is concerning for postobstructive pneumonia and abscess in the setting of bronchial obstruction and immunosuppression. Given the severity of his illness and his recent chemotherapy, his antibiotic regimens should include empiric treatment of methicillin-resistant S. aureus, gram-negative organisms including Pseudomonas species, and anaerobic organisms (answer A is correct). Obligate anaerobic organisms will not grow in routine sputum microbiologic cultures but are considered important pathogens in postobstructive pneumonia and should be treated empirically (answer D is incorrect). Antibiotic regimens for anaerobic coverage may include betalactam/beta lactamase inhibitor combination, metronidazole, clindamycin, or carbapenem antibiotics. Lung abscesses often require prolonged treatment that is guided by repeat imaging (answer B is incorrect). Unfortunately, unless his cancer is successfully treated, he will be at ongoing risk for postobstructive pneumonia (answer C is incorrect).