A 37-year-old presents to the emergency department due to fever and chest pain for the past nine days. The pain is sharp, midsternal, worsens with lying down, and improves with leaning forward. The patient also had an
upper respiratory tract infection one week ago. Temperature is 38.2°C (100.8°F),
pulse is 108/min, respirations are 22/min, and
blood pressure is 140/74 mmHg. On
auscultation there is a friction rub heard at the left lower
sternal border. Laboratory evaluation shows elevated ESR and CRP. ECG is significant for
normal sinus rhythm with diffuse
ST segment elevation of 1 to 2 mm. Which of the following best describes the class of pathogen causing this patient’s symptoms?