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[Pneumocystis carinii infection. Various aspects on its clinical and laboratory diagnosis]
M Lorca1, R Tassara, M Denegri
1Departamento de Pediatría, Facultad de Medicina (División Cs. Médicas Occidente) Universidad de Chile, Santiago.
Abstract:
P carinii is an opportunistic pathogenic agent able to produce severe infection that must be diagnosed promptly. We analyzed 138 samples from 100 patients suspected of having infection by P carinii. The ortho-toluidine blue and the methenamine stains were used to analyze the samples. Infection was demonstrated in 18 patients, 13 adults and 5 children. Underlying disease was AIDS in 7 and other immunosuppressive disorders in the rest. No immunocompetent patient was infected with P carinii. Proper sample collection is important for diagnosis. When bronchoalveolar lavage is not possible, pharyngo-tracheal aspirate in children and sputum sampling after assisted coughing in adults are recommended. At least 2 staining methods and proper controls are advisable.
Insights
Pneumocystis pneumonia (PCP) requires prompt diagnosis. This study found PCP in 18 of 100 immunocompromised patients, highlighting the importance of appropriate sample collection and staining methods for accurate detection.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Diagnostic Pathology
Context:
- Pneumocystis pneumonia (PCP), caused by Pneumocystis jirovecii (formerly P. carinii), is a significant opportunistic infection.
- Immunocompromised individuals, particularly those with AIDS or other immunosuppressive conditions, are at high risk for severe PCP.
- Prompt and accurate diagnosis is crucial for effective treatment and improved patient outcomes.
Purpose:
- To evaluate the diagnostic utility of ortho-toluidine blue and methenamine silver stains for detecting Pneumocystis jirovecii in patient samples.
- To identify optimal sample collection methods for diagnosing PCP in both adult and pediatric populations.
- To determine the prevalence of PCP in a cohort of patients suspected of having the infection.
Summary:
- A total of 138 samples from 100 patients were analyzed using ortho-toluidine blue and methenamine silver staining.
- PCP was confirmed in 18 patients (13 adults, 5 children), all of whom had underlying immunosuppressive conditions (7 with AIDS).
- No immunocompetent individuals in the study group were found to be infected with Pneumocystis jirovecii.
Impact:
- The study underscores the necessity of using at least two staining methods and proper controls for reliable PCP diagnosis.
- Recommended alternative sample collection methods include pharyngo-tracheal aspirate in children and sputum sampling in adults when bronchoalveolar lavage is not feasible.
- Findings emphasize that PCP is exclusively an opportunistic infection, occurring only in immunocompromised hosts.