Search for agents causing atypical pneumonia in HIV-positive patients by inhibitor-controlled PCR assays.

Pneumonia is one of the most frequent complications in acquired immunodeficiency syndrome-patients with Pneumocystis carinii as the leading cause. The true prevalence of atypical agents such as Chlamydia pneumoniae, C. trachomatis, Legionella pneumophila and Mycoplasma pneumoniae in this population of patients is unknown as the currently used method for diagnosing these agents is measurement of antibody levels. However, this method is of limited value in human immunodeficiency virus (HIV)-positive patients who may have a compromised antibody response. To evaluate the prevalence of Chlamydia spp., Legionella spp. and M. pneumoniae in HIV-infected patients with pulmonary disease, this retrospective study has applied inhibitor-controlled polymerase chain reaction analyses on 103 bronchoalveolar lavage (BAL) fluids representing 103 episodes of pneumonia in 83 HIV-positive patients. L. pneumophila was detected in 1% of the BAL fluids and M. pneumoniae was found as a coexisting pathogen in 2% of the samples. Chlamydia spp. could not be detected in any of the BAL fluids. By culture and staining methods 106 other microorganisms were detected with P. carinii and Streptococcus pneumoniae as the most frequently occurring. Pneumonia due to Chlamydia pneumoniae, Legionella pneumophila or Mycoplasma pneumoniae seems to be rare in Danish human immunodeficiency virus-infected patients, but might be considered as a possible cause in cases of treatment failure.