Persistently positive culture of antimicrobial-susceptible Legionella pneumophila despite appropriate therapy

Legionella pneumophila is a well-known cause of pneumonia that is infrequently cultured in clinical practice. We report a case of an immunocompromised patient with persistently positive L. pneumophila cultures from invasive respiratory samples despite prolonged treatment with appropriate antibiotics. In vitro testing showed that the isolate remained susceptible to ciprofloxacin and azithromycin.