A 28-year-old male presents with fever, severe headache, shortness of breath, and altered mental status. While in the emergency room, he develops a seizure and is subsequently intubated and placed on mechanical ventilation. Recent medical history is significant for nonspecific complaints of fever, cough, and malaise. His chest radiograph shows mediastinal widening and pleural effusions. A lumbar puncture reveals grossly bloody CSF with low glucose and elevated white blood cell count. Blood and CSF cultures are growing Bacillus anthracis.
Which of the following antibiotic combinations should be started?
A. Ciprofloxacin, Meropenem, and VancomycinCorrect Answer: A
B. anthracis is an encapsulated, gram positive, spore-forming bacterium that can causes pulmonary, meningeal, cutaneous, and gastrointestinal disease. Aerosolized anthrax spores may be used as a biological weapon. The spores are inhaled, phagocytized by alveolar macrophages and carried to mediastinal lymph nodes where they germinate and cause disease through the production of toxins leading to systemic disease and shock.
Early symptoms are nonspecific with fever, cough, myalgia, malaise, and mimic viral illnesses. However, after a short period of apparent recovery, fever, respiratory failure, acidosis, and shock develop. The earliest clue to diagnosis may be radiographic findings of a widened mediastinum and pleural effusions that rapidly progress to a large size. Anthrax meningitis results from hematogenous seeding and occurs in up to 50% of patients with inhalational anthrax. The mortality rate is as high as 67% to 88% even with antimicrobial or antiserum treatment. Diagnostic testing should include blood for culture and polymerase chain reaction assay (PCR), plasma for antitoxin detection, pleural fluid/CSF for culture, and PCR.
The CDC recommends two or more antimicrobial drugs for treatment of B. anthracis. In patients with confirmed and probable meningitis, survival was increased in patients who received three or more antimicrobials. The recommended first line drug for treatment of culture-confirmed anthrax meningitis is a fluoroquinolone. Other antibiotics with good CSF penetration and activity against B. anthracis include penicillin or ampicillin, meropenem, rifampin, and vancomycin. Although doxycycline has good activity against B. anthracis, it has poor CNS penetration and thus, is not recommended for treatment of anthrax meningitis. Because of β-lactam resistance, cephalosporins are contraindicated for the treatment of anthrax.
Patients with anthrax meningitis may need steroids to control cerebral edema and antiepileptic agents to seizures. Early treatment with antibodies directed against anthrax toxins is also recommended.
References: