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Detection of Pneumocystis carinii by DNA amplification in human immunodeficiency virus-positive patients
D Savoia1, M Millesimo, I Cassetta
1Department of Clinical and Biological Sciences, University of Torino, Italy.
Abstract:
The opportunistic pathogen Pneumocystis carinii (PC) is a frequent cause of a life-threatening pneumonia in human immunodeficiency virus (HIV)-infected individuals and in other immunocompromised hosts. Specimens obtained from 128 bronchoalveolar lavage (BAL) fluid samples from 123 HIV-positive patients with pulmonary disease and undergoing a diagnostic bronchoscopy were evaluated to detect this organism. We have developed a rapid DNA extraction procedure for nested polymerase chain reaction (PCR) using two sets of primers (pAZ102-E, pAZ102-H and P1 = 5'-CTAGGATATAGCTGGTTTTC-3' and P2 = 5'-TCGACTATCTAGCTTATCGC-3'). The results were compared using cytological techniques (direct wet mount, Giemsa, toluidine blue O) and related to the clinical follow-up of patients. The nested PCR had a 91% sensitivity and a 93% specificity. The effect of chemoprophylaxis and the evaluation of the follow-up of patients are discussed. Nested PCR may represent an important additional tool, along with current cytological methods, for the detection of P. carinii; however, at present it cannot replace routine microbiological methods more simple and less expensive.
Insights
Nested polymerase chain reaction (PCR) offers a sensitive method for detecting Pneumocystis carinii pneumonia in HIV-positive patients. While effective, this molecular technique complements, but does not replace, simpler, less expensive traditional diagnostic methods.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Molecular Diagnostics
Background:
- Pneumocystis carinii (PC) causes life-threatening pneumonia in immunocompromised individuals, particularly those with human immunodeficiency virus (HIV).
- Accurate and timely diagnosis of PC pneumonia is crucial for effective patient management.
Purpose of the Study:
- To develop and evaluate a rapid DNA extraction procedure for nested polymerase chain reaction (PCR) to detect Pneumocystis carinii.
- To compare the diagnostic performance of nested PCR with conventional cytological techniques.
Main Methods:
- Nested PCR using specific primer sets was performed on bronchoalveolar lavage (BAL) fluid samples from 123 HIV-positive patients.
- Results were compared to direct wet mount, Giemsa, and toluidine blue O staining.
- Clinical follow-up data were analyzed in conjunction with diagnostic results.
Main Results:
- The nested PCR assay demonstrated high sensitivity (91%) and specificity (93%) for detecting Pneumocystis carinii.
- The method showed potential as an additional diagnostic tool for PC pneumonia.
- The study discussed the impact of chemoprophylaxis and patient follow-up.
Conclusions:
- Nested PCR is a valuable adjunct for diagnosing Pneumocystis carinii pneumonia, especially in HIV-positive patients.
- Currently, nested PCR does not supersede simpler and more cost-effective routine microbiological methods.
- Further evaluation is needed to fully integrate PCR into routine diagnostic workflows.