USMLE® Step 2 CK Question of the Day: Influenza medications

A 72-year-old woman in the ED and reports having a cough and shortness of breath. What ‘s her diagnosis and which combinations of medications is best to treat her condition? Do you know? Let’s find out!

A 72-year-old woman presents to the emergency department with 5 days of cough and 2 days of shortness of breath. Five days ago the patient developed myalgias, a headache, nasal congestion, and a low-grade fever which had resolved, but the shortness of breath and cough have worsened. Past medical history is significant for type 2 diabetes mellitus. Current medications include empagliflozin and metformin. Temperature is 39.2 ºC (102.6 ºF), pulse is 90/min, respirations are 20/min, and blood pressure is 110/71 mmHg. Oxygen saturation is 92% on room air. On physical examination, the patient is tachypneic but is not using accessory muscles of respiration. On auscultation, there are rhonchi and decreased breath sounds at the left lung base. Nasal swab is positive for influenza A virus. Serum white blood cell count is 18,000 cells/mm³ and procalcitonin is 1.3 ng/mL. 

Which of the following medication combinations is most appropriate at this time?

A. Peramivir plus azithromycin

B. Oseltamivir plus levofloxacin

C. Oseltamivir plus zanamivir

D. Oseltamivir plus peramivir

E. Zanamivir plus prednisone

Scroll down for the correct answer!

The correct answer to today’s USMLE® Step 2 Question is…

B. Oseltamivir plus levofloxacin

Correct: See Main Explanation.

Incorrect Answer Explanations

A. Peramivir plus azithromycin

Incorrect: Azithromycin alone is inadequate antibiotic coverage for community-acquired bacterial pneumonia, which this patient has developed as a complication of influenza. Additionally, it would not provide adequate coverage for very ill hospitalized patients.

C. Oseltamivir plus zanamivir

Incorrect: There is no indication for combining two different neuraminidase inhibitors. If the patient does not respond well to one and continues to worsen, then it can be discontinued and switched to a different neuraminidase inhibitor.

D. Oseltamivir plus peramivir

Incorrect: There is no indication for combining two different neuraminidase inhibitors. If the patient does not respond well to one and continues to worsen, then it can be discontinued and switched to a different neuraminidase inhibitor.

E. Zanamivir plus prednisone

Incorrect: Adjunctive glucocorticoids may be appropriate for patients with community-acquired pneumonia with impending respiratory failure or on mechanical ventilation, but they would not be indicated in this patient. 

Main Explanation

This patient presents with flu-like symptoms and tests positive for influenza A virus, confirming influenza (“the flu”). This patient also has abnormal breath sounds localized to the left lobe, a new fever, significant leukocytosis, and an elevated procalcitonin which together are highly suggestive of superimposed bacterial pneumonia. In this case, an antiviral neuraminidase inhibitor (oseltamivir) in combination with a pulmonary antibiotic like levofloxacin is the most appropriate treatment regimen.

Influenza is a viral infection that can affect both the upper and lower respiratory tract. It is highly transmissible and isolation precautions should always be taken. Patients may present with “flu-like symptoms” (e.g., fevers, headache, malaise, myalgias), upper respiratory symptoms (e.g., rhinorrhea, nasal congestion), and lower respiratory symptoms (e.g., cough, shortness of breath). Patients with suspected influenza should be evaluated for high-risk features.

If high-risk features (e.g. diabetes mellitus, age over 65 years, severe and progressive symptoms) are present, then patients should be treated empirically with a neuraminidase inhibitor (e.g. oseltamivir) until influenza testing can be performed via nucleic acid amplification of a nasopharyngeal swab. For patients without high-risk features, a neuraminidase inhibitor is typically given only if symptoms began ≤48 hours before the patient presented. However, patients like this one, with high-risk features, should be prescribed a neuraminidase inhibitor even though she presented at > 48 hours after symptom onset.

Major Takeaway

Patients with influenza should be categorized based on the presence or absence of high-risk features. Patients with high-risk features should receive a neuraminidase inhibitor even if they present > 48 hours after symptom onset. Patients with influenza who develop superimposed bacterial pneumonia as a complication of influenza should be treated with antibiotics.

Want to learn more about this topic?

Watch the Osmosis video: Influenza: Clinical sciences

References

• Metlay JP, Waterer GW, Long AC, Anzueto A, Brozek J, Crothers K, Cooley LA, Dean NC, Fine MJ, Flanders SA, Griffin MR, Metersky ML, Musher DM, Restrepo MI, Whitney CG. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019 Oct 1;200(7):e45-e67. doi: 10.1164/rccm.201908-1581ST. PMID: 31573350; PMCID: PMC6812437.
• Uyeki, T. M., Bernstein, H. H., Bradley, J. S., Englund, J. A., File, T. M., Fry, A. M., Gravenstein, S., Hayden, F. G., Harper, S. A., Hirshon, J. M., Ison, M. G., Johnston, B. L., Knight, S. L., McGeer, A., Riley, L. E., Wolfe, C. R., Alexander, P. E., & Pavia, A. T. (2019). Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 68(6), 895–902.

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