INTRODUCTION: Myocarditis is an inflammatory disorder of the myocardium with necrosis of the myocytes. In the United States, viral infections account for most cases. We present a case of Mycoplasma pneumoniae-associated myocardial necrosis.
CASE PRESENTATION: A 16 year old male with a past medical history significant for autism presented to the pediatrics clinic with a two day history of fever, dyspnea, cough, vomiting and diarrhea. He was given ceftriaxone 2 grams IM and was directly admitted to the pediatric wards with a diagnosis of pneumonia. Presenting physical examination revealed a temperature of 39°C, blood pressure 90/60, pulse of 146/minute, respirations of 65/minute and pulse oximetry of 85% on 100% non-rebreather. Lung examination revealed moderate crackles and bibasilar diminished breath sounds. Cardiac auscultation revealed sinus tachycardia. Complete blood count and chemistries were within normal limits. Chest radiograph revealed right-sided multi lobar reticulonodular infiltrates. Patient received azithromycin 500 mg IVPB, vancomycin 1 gm IVPB and clindamycin 600 mg IVPB. He was intubated and transferred to the Pediatric Intensive Care Unit (PICU) for further management. Shortly after arrival to the PICU, the patient experienced asystole and required cardiopulmonary resuscitation with return of spontaneous circulation. Post-resuscitation transthoracic echocardiogram revealed an ejection fraction of 10–15%; cardiac enzymes were elevated, with troponin-I of 300 ng/mL, and CK-MB of 289 ng/mL at their zenith. The patient was taken emergently for cardiac catheterization and intra-aortic balloon pump placement for refractory hypotension despite vasopressors. Coronary angiography revealed normal coronaries and pulmonary artery catheterization was consistent with cardiogenic shock. The patient's respiratory and hemodynamic status continued to decline until he developed pulseless electrical activity from which he could not be resuscitated. Post-mortem cultures and serology for bacteria and viruses were negative except for Mycoplasma IgM by enzyme immunoassay (EIA). At autopsy, gross, patchy necrosis of the myocardium was confirmed by histology and characterized microscopically by significant lymphocytic infiltrate. These findings in conjunction with the clinical history and serology support a diagnosis of fulminant myocarditis secondary to Mycoplasma pneumoniae infection.
DISCUSSIONS: Mycoplasma pneumoniae causes 15–20% of adult community-acquired pneumonias (CAP). There is an increased incidence of infections during the summer months, which is related to the decreased incidence of other pathogens. M. pneumoniae is transmitted person-to-person by respiratory droplets. Patients most commonly present with sore throat, cough and constitutional symptoms. Typical roentgenographic findings are peribronchial and perivascular infiltrates located centrally in the mid lung zone. 25% of patients with Mycoplasma infections will also have extrapulmonary manifestations such as dermatologic, central nervous system (CNS), gastrointestinal, and hematologic. Though the CNS is most commonly affected, cardiac involvement tends to be the most severe. 1–5% of patients infected will have cardiac involvement, which usually presents as pericarditis or myocarditis. In clinical practice, diagnostic studies to confirm Mycoplasma are rarely performed. While culture and serology are widely available, serology has become the mainstay as culture may take up to two weeks to return positive. Newer methods such as enzyme immunoassay (EIA), as used in our institution, allows for rapid results with a sensitivity of 77% and specificity of 92%. Treatment efficacy has been demonstrated for tetracycline, fluoroquinolones, and macrolides. In cases of associated pericarditis, consider prolonged courses of macrolides and pericardiocentesis with or without corticosteroids. If there is significant myocardial injury, therapy is supportive in addition to antibiotics. The differential diagnosis for roentgenographic infiltrates with myocarditis includes adenovirus, influenza A and B, respiratory syncytial virus, Hemophilus influenzae, Legionella pneumophila, Mycoplasma pneumoniae, Streptococcus pneumoniae, and Staphylococcus aureus.
CONCLUSION: Mycoplasma pneumoniae is a common cause of community-acquired pneumonia that can have multi-organ involvement. To our knowledge, this is the first case of fatal acute myocardial necrosis related to Mycoplasma infection.
DISCLOSURE: Shantanu Naik, No Financial Disclosure Information; No Product/Research Disclosure Information