Severe cytomegalovirus (CMV) community-acquired pneumonia (CAP) in a nonimmunocompromised host

Community-acquired pneumonia (CAP) in an immunocompetent host may be severe because of a variety or combination of host and microbial factors. In patients with severe cardiopulmonary dysfunction, even relatively avirulent pathogens, that is, Mycoplasma pneumoniae, Moraxella catarrhalis, may compromise borderline cardiac/heart function and present clinically as severe CAP. Alternately, patients with Streptococcus pneumoniae and impaired humoral immunity/splenic dysfunction may present as severe CAP. With the exception of Legionnaire's disease, influenza, and adenovirus, pathogen virulence is not a key determinant of CAP severity.

Diagnostically, patients with severe CAP may be approached based on the pattern of infiltrates on chest x-ray together with the severity of hypoxemia (ie, increased A-a gradient: >35).

We present the case of an immunocompetent adult who presented with severe CAP during peak influenza season. Direct fluorescent antibody testing of his respiratory secretions was negative for influenza, adenovirus, and other respiratory viruses. Diagnostic bronchoscopy was negative for bacterial and fungal pathogens. The only clues to the cause of his severe CAP was the presence of relative lymphopenia, atypical lymphocytosis and elevated serum transaminases. After influenza and adenovirus were ruled out, cytomegalovirus (CMV) CAP was considered. The diagnosis of CMV CAP was made serologically by demonstrating highly elevated IgM CMV titers. Because the diagnosis was made during the patient's recovery late in hospitalization, he did not receive CMV antiviral therapy.

This case should remind clinicians that influenza and adenovirus are diagnostic considerations in patients presenting with severe CAP with diffuse bilateral interstitial infiltrates accompanied by severe hypoxemia in normal hosts. If influenza and adenovirus are ruled out, then CMV CAP, although rare, should be considered, particularly when viral CAP is accompanied by relative lymphopenia, atypical lymphocytosis and increased serum transaminases.