Pneumonia Caused by Three Separate Microorganisms Simultaneously in a Patient Infected with Human Immunodeficiency Virus

Community-acquired pneumonia (CAP) is usually caused by a single microorganism. is the most common organism associated with CAP. However, in immunocompromised patients, especially those infected with human immunodeficiency virus (HIV), pneumonia may be caused by multiple organisms simultaneously. This report describes a previously healthy 29-year-old man who presented with acute CAP. Blood tests showed that he was positive for HIV antigen/antibody, and urinalysis showed that he was initially positive for pneumococcal antigen. Although blood cultures showed growth of , he did not respond to invasive anti-pneumococcal treatment with ceftriaxone and vancomycin. Rather, his pneumonia worsened, and he was intubated for hypoxic respiratory failure. His bronchoalveolar lavage fluid was positive for and methicillin-resistant . These findings indicate that pneumonia in immunocompromised patients may be caused by multiple organisms. Patients who fail to respond to treatment for a single identified organism should be suspected of being infected with other pathogenic organisms.