Mycoplasma Pneumonia and Influenza B Co-infection in an Adult.

Community-acquired pneumonia (CAP) is a significant cause of morbidity and mortality among adults worldwide, frequently resulting in prolonged hospitalization. Co-infection with both viral and bacterial microorganisms is an important contributor to this morbidity. Streptococcus pneumoniae is the most common causative agent of CAP; however, including atypical bacteria in the differential diagnosis may facilitate timely treatment and improve patients' outcomes. Here, we present a 50-year-old female with a recent household exposure to influenza B who developed progressive hypoxemia despite outpatient management and required hospitalization. In-hospital testing confirmed Mycoplasma pneumoniae infection; influenza A/B testing at admission was negative, consistent with resolution of her preceding, non-laboratory-confirmed influenza B illness. Appropriate treatment resulted in resolution of hypoxemia and successful discharge. This case underscores the importance of early consideration of atypical bacterial co-infections in patients presenting with severe CAP, which may reduce the likelihood of prolonged hospitalization.