A 72-year-old man comes to the hospital due to 12 hours of worsened shortness of breath and nonproductive cough. He was in his usual state of health until 3 days ago, when he abruptly developed fever, headache, sore throat, runny nose, anorexia, and severe body aches. The patient has no known sick contacts but spent a long time in a mall shopping for Christmas presents 5 days ago. He has a history of coronary artery disease, hypertension, and diet-controlled type 2 diabetes mellitus. Temperature is 38.9 C (102 F), blood pressure is 140/90 mm Hg, pulse is 102/min, and respirations are 28/min. Oxygen saturation is 91% on 40% supplemental oxygen via mask. Oropharyngeal examination shows mild pharyngeal erythema without exudates. No lymphadenopathy or jugular venous distension is present. Chest auscultation reveals scattered bilateral crackles and a fourth heart sound (S4) but no cardiac murmurs. The abdomen is soft and nontender. There is no peripheral edema. Laboratory results are as follows: Chest x-ray reveals bilateral, diffuse reticular opacities. Which of the following is the most likely underlying cause of this patient's current condition?

Question

A 72-year-old man comes to the hospital due to 12 hours of worsened shortness of breath and nonproductive cough.  He was in his usual state of health until 3 days ago, when he abruptly developed fever, headache, sore throat, runny nose, anorexia, and severe body aches.  The patient has no known sick contacts but spent a long time in a mall shopping for Christmas presents 5 days ago.  He has a history of coronary artery disease, hypertension, and diet-controlled type 2 diabetes mellitus.  Temperature is 38.9 C (102 F), blood pressure is 140/90 mm Hg, pulse is 102/min, and respirations are 28/min.  Oxygen saturation is 91% on 40% supplemental oxygen via mask.  Oropharyngeal examination shows mild pharyngeal erythema without exudates.  No lymphadenopathy or jugular venous distension is present.  Chest auscultation reveals scattered bilateral crackles and a fourth heart sound (S4) but no cardiac murmurs.  The abdomen is soft and nontender.  There is no peripheral edema.  Laboratory results are as follows:  Chest x-ray reveals bilateral, diffuse reticular opacities.  Which of the following is the most likely underlying cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d459_949f_bc81_2b997d126e8a_MD0003_00 Influenza virus is largely a winter infection that attacks the epithelium of the upper and lower respiratory tract. Approximately 1-5 days after exposure, patients abruptly develop systemic (fever, malaise, myalgias, headache) and upper/lower respiratory (rhinorrhea, sore throat, nonproductive cough) symptoms. Physical and laboratory examinations are often normal but may show pharyngeal erythema (without exudates) and mild alterations in leukocyte count (low early, high later). Most patients recover spontaneously and completely within 1 week of symptom onset. However, patients with advanced age (>65) and chronic medical illness (eg, coronary artery disease, diabetes mellitus) are far more likely to develop complications. Pneumonia is the most common complication of influenza and is the result of either secondary bacterial infection (eg, Streptococcus pneumoniae) or direct viral attack (influenza pneumonia). Patients with primary influenza pneumonia typically have an acute worsening of symptoms (dyspnea, cough), leukocytosis (although <15,000/mm³), hypoxia, and bilateral, diffuse interstitial infiltrates on chest x-ray. Hospitalization with supplemental oxygen support and antiviral (eg, oseltamivir) treatment is usually required. Influenza may also cause complications in the muscle (myositis, rhabdomyolysis), heart (myocarditis, pericarditis), and central nervous system (encephalitis, transverse myelitis). (Choice A) Cytomegalovirus infection may cause a mononucleosis-like illness marked by fever, malaise, and absolute lymphocytosis. Rhinorrhea is uncommon and pulmonary involvement rarely occurs unless there is significant immunocompromise (eg, HIV with CD4 <100/mm³). (Choice B) Group A Streptococcus infection can cause fever and sore throat with tonsillar exudates (pharyngitis). This patient's pulmonary involvement, rhinorrhea, and myalgias indicate an alternate diagnosis. (Choice D) Pneumocystis pneumonia is almost always seen in patients with significant immunocompromise (eg, solid organ transplantation, HIV with CD4 <200/mm³) and is marked by fever, cough, dyspnea, and (often) chest x-ray evidence of bilateral interstitial infiltrates. This condition is usually subacute and is not commonly associated with rhinorrhea and myalgias. (Choices E and G) Streptococcus pneumoniae, Staphylococcus aureus, and (less commonly) Pseudomonas aeruginosa can cause secondary bacterial pneumonia in patients with influenza. Patients with these infections have high fever, significant leukocytosis (>15,000/mm³), and lobar infiltrates on chest x-ray. This patient with mild leukocytosis and bilateral, diffuse reticular infiltrates on chest x-ray likely has primary influenza pneumonia. (Choice F) Respiratory syncytial virus (RSV) infection and influenza share many clinical symptoms, but patients with RSV often have wheezing and rarely (<1%) have diffuse, bilateral reticular infiltrates. Educational objective: Influenza is usually a self-limited infection marked by <1 week of systemic (fever, malaise, myalgias, headache) and respiratory (rhinorrhea, sore throat, nonproductive cough) symptoms. Complications (eg, pneumonia) are common in patients with advanced age and chronic illness.

A 72-Year-Old Man Comes to the Hospital Due to 12