A 57-year-old government employee who works to counter bioterrorism without any pertinent medical history is exposed to a small amount of an unknown white powder on his skin. Over 4 days, he develops a flulike illness with symptoms including malaise, fever, and fatigue. On presentation to the emergency department, he has a :
Physical examination is notable for the skin lesion figure below:
Laboratory studies are notable for a WBC of 10,800. Gram staining of the substance reveals large, spore-forming, gram-positive bacilli.
The patient is placed in isolation and admitted to the general medical service. Twelve hours after admission, the patient becomes increasingly altered. He endorses nuchal rigidity and photophobia, is unable to formulate complete sentences, and is transferred to the ICU. Lumbar Puncture demonstrates:
In addition to antitoxin, which of the following antibiotic(s) should be empirically started on this patient in the ICU?
Correct Answer: B
This patient likely has been exposed to anthrax. Bacillus anthracis is a gram-positive, aerobic, capsulated, spore-forming, rod-shaped bacterium. It can be transmitted through cutaneous exposure, inhalation, ingestion, and injection, with each transmission method posing the potential for systemic progression. Patients first develop a prodromal flulike illness. However, there are fatal complications of anthrax, most notably hemorrhagic mediastinitis and meningitis.
Anthrax meningitis is almost invariably fatal. Patients may present with fever, neck rigidity, altered mental status, and with LP findings consistent with bacterial meningitis: elevated opening pressure, elevated WBCs with neutrophil predominance, elevated protein, and low glucose. In addition, the presence of frank blood or RBCs is also common given that anthrax meningitis may have a hemorrhagic component. Anthrax meningitis requires broad spectrum antibiotics with multiple antibiotic modalities and CSF penetration (B). This treatment should include at least one protein synthesis inhibitor to reduce exotoxin production.
Moxifloxacin and clindamycin (A) would be appropriate empiric coverage for cutaneous anthrax without evidence of meningitis. However, linezolid has significantly better CNS penetration compared with clindamycin. Cefepime and vancomycin (C) are broad spectrum antibiotics with strong gram-positive and -negative coverage; however, studies have demonstrated that cephalosporins, including cefepime, have unreliable coverage of B. anthracis. Levofloxacin and other fluoroquinolones are often first line treatment for cutaneous anthrax; however, they would not be adequate coverage for anthrax meningitis.
References:
Twelve employees of a clothing factory are transported to the emergency department after a fire at their factory. The factory utilizes wool, silk, and multiple other clothing products. The group was in the building for 2 hours while the fire was ablaze. A 55-yearold male who was found located close to the fire presents with headache, vomiting, and altered mental status. He also reports a “bitter almond” smell. Initial examination is notable for:
T37.0°C (98.6°F)
HR 121/min
BP 160/96 mm Hg
O2 saturation of 92% on room air
The patient appears flushed. His clothing is removed, and his skin is rinsed with soap and water.
As laboratory test results are pending, the patient has multiple episodes of convulsions and is intubated for airway protection. Laboratory test results are shown in the table below:
Which of the following treatments for cyanide toxicity should be AVOIDED in this patient?
Correct Answer: A
This patient presents with headache, vomiting, and altered mental status after prolonged smoke exposure, which is concerning for cyanide toxicity. Initial treatment for cyanide toxicity includes removal from the exposure, decontamination, and airway protection. Patients with inhalation cyanide toxicity secondary to smoke exposure often copresent with carbon monoxide poisoning. There are multiple modalities to definitively treat cyanide toxicity, including sodium nitrite, sodium thiosulfate, hydroxocobalamin, and 100% or hyperbaric oxygen.
Sodium nitrite (A) is effective in treating cyanide by inducing methemoglobinemia. This leads to the oxidation of iron in hemoglobin to form the ferric ion. Cyanide can bind with the formed methemoglobin structure, which creates cyanomethemoglobin, which is less toxic than other cyanide products. However, the formation of methemoglobin shifts the oxygen dissociation curve to the left, which can be harmful for patients with concurrent carbon monoxide poisoning. As such, the induction of methemoglobinemia in patients with both cyanide poisoning and carbon monoxide poisoning has the potential to be lethal and should be avoided in these patients.
Sodium thiosulfate (B) works by providing sulfur donors, which can convert cyanide to thiocyanate. Thiocyanate is readily excreted through the kidneys and is a reasonable treatment for this patient. Hydroxocobalamin works by binding to intracellular cyanide with greater affinity than cytochrome oxidase and forms cyanocobalamin. This structure can be excreted in the urine and works rapidly. Studies have found that 100% oxygen and hyperbaric oxygen can improve outcomes in cyanide poisoning. This patient may have concomitant carbon monoxide poisoning, with which 100% oxygen would be a cornerstone of treatment.
Multiple villagers in a war-torn Middle Eastern country are exposed to an unknown toxic agent. They present to a medical facility complaining of abdominal pain, diarrhea, frequent urination, and excessive tearing in their eyes. Physical examination is notable for bradycardia, miosis, and salivary secretions.
Which of the following is the most likely agent and what is the appropriate antidote?
These patients are presenting with cholinergic toxidrome consistent with organophosphate poisoning. Sarin nerve gas is a colorless and odorless nerve agent that blocks the acetylcholinesterase enzyme that leads to the accumulation of acetylcholine at the neuromuscular junction. This can lead to a cholinergic crisis with the symptomatology described above. Symptoms include salivation, lacrimation, urination, diarrhea, GI pain, and emesis. The extreme of organophosphate poisoning is the sequelae of bradycardia, bronchorrhea, and bronchospasm, which can be fatal. The villagers in the question stem would likely need close monitoring of their airway with a low threshold for intubation, as they have evidence of increased secretions on physical examination.
Atropa belladonna (B) is also known as deadly nightshade and contains atropine, hyocyamine, and scopolamine. It can lead to an anticholinergic toxidrome characterized by tachycardia, dry and flushed skin, altered mental status, and mydriasis, with the potential for significant neurologic dysfunction at high doses. Benzodiazepine overdose (C) would be characterized by lethargy, ataxia, and respiratory depression. It is unlikely in this group of people, and the clinical symptoms would differ from those described in this question. Arsenic ingestion (D) is characterized by prominent GI symptoms as well as jaundice, hematuria, and altered mental status. Subacute poisoning would present with anemia and peripheral neuropathy, which are not characterized by the individuals in the given question.
A 56-year-old male who was working at a nuclear power plant presents to the emergency department complaining of significant nausea and vomiting. Initial vitals are:
Physical examination is otherwise unremarkable. He is decontaminated, placed in isolation, and admitted to the ICU for further management. It is estimated that he was exposed to 4 -6 Gy of radiation.
On day 8 of admission, his laboratory studies are notable for:
In patients with hematopoietic radiation injury, which of the following is NOT a recommended component of treatment?
Correct Answer: C
Radiation injuries are largely dependent on the exposure burden for patients, and a patient’s clinical course can often be predicted based on exposure. Patients exposed to 0 -2 Gy are unlikely to have significant complications from their radiation exposure. Patients with 2 -9 Gy may have significant sequelae from their exposure and require significant monitoring and care. Hematopoietic cell transplantation has been described as potentially beneficial for patients with Gy exposure between 2 and 9. Exposure greater than 10 Gy is almost invariably fatal (see Radiation Injury Doses and Syndromes and Phases of Radiation Injury tables). Considering the fatality rates of greater exposures and the limited resources available for transplantation, it has been documented that it is unwise to transplant patients with greater exposure (C).
Granulocyte colony-stimulation factor (A) has been shown to be beneficial for patients with significant exposure. Recommendations include daily administration of G-CSF until neutropenia resolves. For patients with significant cytopenia, including those with ANCs <500, empiric antibiotics (B) are highly recommended as a cornerstone of therapy. Recommended prophylactic therapy would likely include the use of a penicillin with beta-lactamase inhibition or the use of fluoroquinolones that have been shown to improve mortality in neutropenic patients. Regarding the administration of blood products, patients with hematopoietic radiation injury benefit greatly from supportive care and routine administration of blood products for anemia and thrombocytopenia. It is critical that these blood products undergo leukoreduction and irradiation (D) to limit significant transfusion reactions, most notably graft-versus-host disease.
Radiation Injury Doses and Syndromes:
Adapted from Lopez M, Martin M. Medical management of the acute radiation syndrome. Rep Pract Oncol Radiother. 2011;16:138-146.
Phases of Radiation Injury:
Adapted from Waselenko JK, MacVittie TJ, Blakely WF, et al. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med. 2004;140:1037-1051.
A 55-year-old male presents to an emergency department in China with a 5-day history of cough, fever, and myalgias. On presentation, his:
Chest X-ray demonstrates a left lower lobe pneumonia. He receives 2 L of lactated ringers, is started on empiric broad spectrum antibiotics with cefepime and vancomycin, and is admitted to an isolated bed on the general medicine floor for further management. Two days after admission, he develops a worsening oxygen requirement, is transferred to the ICU, where he is ultimately intubated for hypoxic respiratory failure. His CXR just before intubation is shown below.
A nasopharyngeal aspirate and endotracheal aspirate are ultimately positive for Avian Influenza A H7N9.
Which of the following is true regarding the management of H7N9?
As confirmed by laboratory testing, this patient has avian bird flu, H7N9. H7N9 is highly virulent form of influenza with the first cases of this new strain of influenza reported in 2013 in China. Patient’s clinical presentations may vary but have often included the acute onset and rapid progression of common influenza symptoms. In addition, many patients have presented with leukopenia, lymphopenia, and thrombocytopenia. The severity of the illness often correlates with the baseline health of the infected patient; however, over 75% of patients were reported to be admitted to the ICU while hospitalized, and over 25% of patients have died.
The CDC published interim guidelines in 2013 regarding treatment for patients with H7N9. For those admitted to the hospital, antiviral treatment with neuroaminidase inhibitors (oseltamivir or zanamivir) is recommended. It is recommended that these antiviral agents are included in treatment even after 48 hours of illness onset, especially for patients admitted to the hospital. For other forms of influenza, it is debated whether oseltamivir should be included in treatment after 48 hours.
Inhaled Zanamivir should be avoided in patients with underlying airway disease (A), and instead oseltamivir or IV formulations should be used. There is no difference in outcomes when comparing IV zanamivir and PO oseltamivir (C). Zanamivir would only be preferred if the patient is unable to tolerate PO medications. Additionally, for patients with presumed avian flu, antivirals should be included in treatment even while laboratory testing is pending. The recommended test for H7N9 is the utilization of real-time reverse-transcriptase polymerase chain reaction for avian influenza A H7N9 on an oropharyngeal or nasopharyngeal aspirate. This study will likely include send-out laboratory testing, and treatment should not be delayed while results are pending.
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