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Search for agents causing atypical pneumonia in HIV-positive patients by inhibitor-controlled PCR assays
B Tarp1, J S Jensen, L Ostergaard
1Dept of Infectious Diseases, Aarhus University Hospital, Denmark.
Abstract:
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.
Insights
Pneumonia in HIV patients is often caused by Pneumocystis carinii. Atypical agents like Chlamydia, Legionella, and Mycoplasma pneumoniae are rare, but polymerase chain reaction can detect them.
Area of Science:
- Infectious Diseases
- Immunology
- Pulmonology
Background:
- Pneumonia is a frequent complication in patients with acquired immunodeficiency syndrome (AIDS).
- Pneumocystis carinii pneumonia (PCP) is the leading cause, but atypical pathogens are underdiagnosed due to unreliable antibody testing in human immunodeficiency virus (HIV)-positive individuals.
- Antibody-based diagnostics are limited in HIV patients with compromised immune responses.
Purpose of the Study:
- To determine the prevalence of Chlamydia spp., Legionella spp., and Mycoplasma pneumoniae in HIV-infected patients with pneumonia.
- To evaluate the utility of polymerase chain reaction (PCR) for diagnosing these atypical pathogens in this population.
Main Methods:
- Retrospective analysis of 103 bronchoalveolar lavage (BAL) fluid samples from 83 HIV-positive patients with pneumonia.
- Inhibitor-controlled PCR was used to detect Chlamydia spp., Legionella pneumophila, and Mycoplasma pneumoniae.
- Conventional culture and staining methods were used to identify other microorganisms.
Main Results:
- Legionella pneumophila was detected in 1% of BAL fluids.
- Mycoplasma pneumoniae was identified as a co-pathogen in 2% of samples.
- Chlamydia spp. were not detected in any samples. Pneumocystis carinii and Streptococcus pneumoniae were the most common pathogens identified by culture and staining.
Conclusions:
- Pneumonia caused by Chlamydia pneumoniae, Legionella pneumophila, or Mycoplasma pneumoniae appears to be rare in Danish HIV-infected patients.
- These atypical agents should be considered in cases of treatment failure, especially when conventional diagnostics are inconclusive.