Pratibha Shamanna, Muralidhara Sethumadhavan,
Volume 12, Issue 1 (3-2024)
Abstract
Introduction: Pneumocystis jirovecii pneumonia (PCP) remains a significant cause of pneumonia among immunocompromised individuals, despite a decline in prevalence with the advent of antiretroviral therapy (ART) for Human Immunodeficiency Virus (HIV). This study aimed to evaluate and compare the diagnostic accuracy of four distinct staining techniques for PCP in respiratory specimens. We assessed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of these techniques against the gold standard Gomori Methenamine Silver stain (GMS), in order to identify the most effective method for diagnosing PCP. Methods: In a prospective observational study, we collected induced sputum (IS) and BAL samples from 100 immunocompromised patients and examined them microscopically for P. jirovecii cysts. We employed four staining methods for detection: Calcofluor White, Modified Toluidine Blue, Wright's stain, and Gomori Methenamine Silver stain. Results: The combination of Modified Toluidine Blue, Calcofluor White, and Wright's stains detected P. jirovecii cysts in 5% of the study population. The sensitivity of the staining methods was: 80% for Modified Toluidine Blue, 40% for Calcofluor White, and 20% for Wright's, compared to the Gomori Methenamine Silver (GMS) stain, which was used as the gold standard. All the staining methods exhibited equivalent specificity (100%). Conclusion: The Modified Toluidine Blue stain is a viable alternative to the Gomori Methenamine Silver stain due to its simplicity, speed, and applicability in resource-limited settings. The low prevalence of P. jirovecii in this study population suggests that routine cotrimoxazole prophylaxis may be effective in reducing the incidence of P. jirovecii pneumonia among HIV patients.
