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?
Correct 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.
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A 53-year-old female presents with mydriasis, ptosis, diplopia, dysphagia, dysarthria, and a progressive, symmetric descending flaccid paralysis. She is conscious and has no cardiovascular perturbations. Colleagues at other area hospitals are reporting several similar cases. You recommend to:
Correct Answer: C
Clostridium botulinum produces neurotoxins (types A–G) that block acetylcholine release and affect both nicotinic and muscarinic receptors. Symptoms of botulism include an acute, afebrile, symmetric, descending flaccid paralysis, and prominent bulbar palsies (diplopia, dysarthria, dysphonia, and dysphagia). Blockade of muscarinic receptors result in postural hypotension, nausea, and vomiting from ileus. Respiratory muscle involvement can result in respiratory failure. Mental status is not affected; patients usually have a clear sensorium.
The diagnosis of botulism must be done on a clinical basis as laboratory testing is specialized and requires several days to complete. Differential diagnosis includes Guillain-Barre Syndrome, myasthenia gravis, tick paralysis, organophosphate toxicity, and tick paralysis. Distinguishing features of botulism include prominent cranial nerve palsies initially, symmetric, descending progression, and absence of sensory nerve dysfunction.
Features suggestive of bioterrorism as cause of an outbreak of botulism include a large number of cases, outbreak with an unusual botulinum toxin type, outbreak in a location without a common dietary exposure, and multiple outbreaks at the same time without common source.
Treatment of botulism is largely supportive. Antitoxin should be administered in a timely basis (most effective if given within 24 hours). The antitoxin will limit the severity of disease and subsequent nerve damage but will not reverse existent paralysis.
The emergency department calls to inform you that there are multiple patients with symptoms of fever, altered mental status, respiratory failure, and shock that will be transferred to the ICU. Features that the patients may be victims of a biologic attack include all of the following EXCEPT:
Correct Answer: D
Bioterrorism refers to the use of biologic agents as weapons to further personal or political agendas. Unlike other methods of terrorism, the effects are not always immediately apparent and can be difficult to distinguish from an outbreak of a naturally occurring infectious disease. Features of a possible bioterrorism-related attack include:
A 54-year-old postal worker presents with symptoms of chest tightness, cough, dyspnea, and fever. Chest radiograph shows pulmonary edema. He is intubated secondary to severe hypoxia and transferred to the ICU. Per report, he was handling a broken vial containing a white powder, and the post office is currently being decontaminated. Management of this patient includes:
Ricin is a toxin derived from the castor bean plant. When purified, it is a white powder that is soluble in water. It can be disseminated as an aerosol, by adding to food or water, and by injection. It inhibits protein synthesis leading to cell death. Other mechanisms of toxicity include affecting apoptosis pathways, direct cell membrane damage, and release of cytokines.
Clinical effects depend on the route of exposure. Initial symptoms of ingestion of ricin can mimic gastroenteritis with abdominal pain, nausea, vomiting, and diarrhea. Hematemesis and melena may occur. Severe dehydration, kidney and liver failure, and death may occur. Symptoms of inhalation of ricin include fever, cough, chest tightness, and respiratory distress. Diffuse pulmonary edema can occur leading to respiratory failure. Smaller ricin particles result in higher mortality because they can be deposited deeper into the respiratory tract. Symptoms after injection of ricin may be delayed as much as 10 to 12 hours are initially nonspecific (fever, headache, nausea, abdominal pain, hypotension) and may progress to multiorgan failure.
There is no antidote for ricin and treatment is supportive. Ricin is not contagious, so respiratory isolation is not necessary. To prevent systemic absorption, a single dose of activated charcoal may be given to patients with ricin ingestion. It is not recommended for patients who have inhaled ricin.
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