Influenza A and Streptococcus pneumoniae Co-infection Presenting With Cardiomyopathy and Acute Kidney Injury in a Previously Healthy Adult: A Case Report.

Cardiomyopathy is a serious complication of systemic infections, commonly linked to viral myocarditis and sepsis-induced myocardial dysfunction. Although influenza and Streptococcus pneumoniae are independently associated with cardiovascular complications, cases involving concurrent infection with both pathogens in the absence of bacteremia remain exceedingly rare. We describe a case of acute reversible cardiomyopathy in a previously healthy 31-year-old male presenting with shock, acute kidney injury, and left ventricular dysfunction. The patient tested positive for influenza A by reverse transcription polymerase chain reaction (RT-PCR) from a nasopharyngeal swab and Streptococcus pneumoniae via urine antigen assay, without evidence of bacteremia from negative blood cultures. Transthoracic echocardiography on admission revealed a left ventricular ejection fraction (LVEF) of 26% with biventricular dysfunction. Despite initial hemodynamic instability, the patient responded to supportive care including vasopressors, inotropes, antiviral and antibacterial therapy, and was transitioned to guideline-directed medical therapy for heart failure. By day five of hospitalization, repeat echocardiography demonstrated recovery of LVEF to 59% and resolution of organ dysfunction. This case highlights a rare but clinically significant manifestation of infection-induced cardiomyopathy associated with concurrent influenza A and S. pneumoniae infection without bacteremia. Proposed mechanisms include direct viral cytotoxicity, influenza-enhanced translocation of pneumococci into myocardial tissue, and a synergistic immune-mediated inflammatory response. The associated acute kidney injury underscores the severity of systemic involvement. Prompt recognition, comprehensive diagnostic evaluation, and multidisciplinary management were crucial in reversing cardiac dysfunction and achieving full recovery.