A 13-year-old boy is brought to the office due to dry cough lasting 2 weeks. The patient has also had low-grade fever, fatigue, and sore throat. Immunizations are up-to-date, and he received his tetanus-diphtheria-acellular pertussis booster 6 months ago. Temperature is 38.1 C (100.6 F), blood pressure is 105/65 mm Hg, pulse is 86/min, and respirations are 18/min. Oxygen saturation is 98% on room air. On examination, the patient appears tired but not ill. The neck is supple and without lymphadenopathy. The oropharynx is erythematous without exudates. Pulmonary auscultation reveals scattered crackles and rhonchi in both lungs. Cardiac and abdominal examination shows no abnormalities. Which of the following is the most likely cause of this patient's symptoms?

Question

A 13-year-old boy is brought to the office due to dry cough lasting 2 weeks.  The patient has also had low-grade fever, fatigue, and sore throat.  Immunizations are up-to-date, and he received his tetanus-diphtheria-acellular pertussis booster 6 months ago.  Temperature is 38.1 C (100.6 F), blood pressure is 105/65 mm Hg, pulse is 86/min, and respirations are 18/min.  Oxygen saturation is 98% on room air.  On examination, the patient appears tired but not ill.  The neck is supple and without lymphadenopathy.  The oropharynx is erythematous without exudates.  Pulmonary auscultation reveals scattered crackles and rhonchi in both lungs.  Cardiac and abdominal examination shows no abnormalities.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d5fe_dfc7_bc81_45f16257dd26_MD0003_00 This patient has prolonged cough, fever, and bilateral crackles, findings consistent with community-acquired pneumonia. In school-aged children (age ≥5), bilateral pneumonia is most commonly caused by atypical bacteria, including Mycoplasma pneumoniae and Chlamydia pneumoniae. These pathogens are referred to as "atypical" to distinguish them from "typical" bacteria such as Streptococcus pneumoniae, which is the most common cause of focal, lobar pneumonia (Choice F). The presentation of atypical bacterial pneumonia is generally more gradual and less severe than that of pneumococcal pneumonia. Patients often have low-grade fever, malaise, headache, and sore throat, in addition to a prolonged and slowly worsening cough. Chest pain, hypoxia, and respiratory distress are unusual, and patients do not typically appear ill and can continue daily activities (ie, "walking pneumonia"). Auscultation of the chest may reveal bilateral crackles, wheezes, or rhonchi, and chest x-ray, if performed, frequently reveals interstitial infiltrates bilaterally. Treatment of atypical bacterial pneumonia in children is usually with a macrolide (eg, azithromycin). Because M pneumoniae lacks a cell wall, beta-lactam therapy such as amoxicillin (first-line therapy for lobar pneumonia in children) is ineffective. (Choice A) Pertussis can cause prolonged cough, but lower respiratory tract findings (ie, crackles, rhonchi) would not be expected. In addition, this patient was recently immunized against pertussis. (Choice B) Epstein-Barr virus commonly presents in adolescents with fever, sore throat, and lymphadenopathy but rarely causes pneumonia in immunocompetent individuals. (Choice C) Like S pneumoniae, nontypeable Haemophilus influenzae (or type B in unvaccinated patients) can cause acute-onset, lobar pneumonia. However, this patient's prolonged course and bilateral disease make atypical bacteria more likely. (Choice E) Respiratory syncytial virus is an extremely common cause of pneumonia in children age <5, but pneumonia from viruses other than influenza is rare in adolescents. Educational objective: Community-acquired pneumonia in school-aged children is frequently due to atypical bacteria such as Mycoplasma pneumoniae. The presentation is generally mild and often includes fever, prolonged cough, and bilateral crackles on lung examination. References: Diagnosis and management of Mycoplasma pneumoniae in children. (http://www.ncbi.nlm.nih.gov/pubmed/28178776)

A 13-Year-Old Boy Is Brought to the Office Due to Dry