Background: Acute myocarditis is an inflammatory disease of the heart muscle that manifests clinically with a spectrum of symptoms, ranging from mild chest pain to myocardial infarction. It can also be linked to viral or bacterial illnesses like pneumonia. Case summary: A 19-year-old male with no notable medical history reported to the Emergency Department with substernal chest pain radiating to the left arm, accompanied by nausea and profuse perspiration. His vital signs were stable and his physical examination was normal, with the exception of left lower chest crackles. The electrocardiogram revealed ST segment increase in inferior and lateral leads, along with ST depression in leads V1 through V3. A portable chest x-ray revealed a patchy opacity in the lower lobe of the left lung. Invasive coronary angiography revealed normal coronary arteries. Further evaluation with echocardiography and cardiac MRI revealed characteristics of acute myocarditis, including a minimally dilated LV and subtle hypokinesia in the midventricular inferior and lateral segments, as well as mild global hypokinesia in the LV and RV. Perimyocarditis was detected in the patient, and antiplatelet medication were terminated. Due to a low ejection fraction, Bisoprolol, Ramipril, and spironolactone were administered, and he was hospitalised until his intravenous treatments for pneumonia were completed. Further laboratory tests revealed a decrease in troponin T, white blood cell count, and C-reactive protein. He was discharged with medications including spironolactone, metoprolol, Ramipril, and colchicine. Unfortunately, he failed to comply with the directive. On the eighth day of hospitalisation, a discharge ECG revealed sinus rhythm with no ST-T alterations. Conclusion: When evaluating an acute cardiac event, healthcare practitioners should examine the possibility of uncommon bacterial myocarditis and keep in mind that Streptococcus pneumoniae infection might imitate acute MI in otherwise healthy young males. The timely diagnosis and administration of appropriate antibiotics are critical in the treatment of such conditions.