EVALUATION OF A POINT OF CARE TEST FOR HISTOPLASMOSIS: EXPERIENCE FROM A TERTIARY CARE CENTRE IN INDIA

Abstract

Intro: Histoplasmosis is a highly endemic fungal disease often underdiagnosed and is most commonly seen in the immunocompromised population. It is caused by a dimorphic fungus, Histoplasma capsulatum initially involving pulmonary and disseminating to renal, cutaneous, CNS, mediastinal and Gastrointestinal systems. The gold standard for diagnosis remains culture requiring a minimum of a month for identification of the organism which is time-consuming. Our study aimed to evaluate the rapid testing kit of urinary Histoplasma antigen detection by OIDx, giving results in 5 to 20 mins by correlating with clinical improvement as the gold standard after targeted antifungal therapy. Methods: This study involved 165 patients visiting our out-patient clinics and also in-patients from October 2021 to July 2022 in All India Institute of Medical Sciences, New Delhi, India presenting with signs and symptoms mimicking histoplasmosis like PUO, pancytopenia, etc., The first void early morning urine samples were tested for the detection of Histoplasma galactomannan antigen by an immunochromatographic assay. The test is interpreted as positive by the presence of pink/purple lines at the test and control lines. Findings: A clear positive result was shown in 32, faint positive in 16, and negative in 117 patient's samples. Antifungal therapy with either Liposomal Amphotericin-B or itraconazole was given in patients based on clinical symptoms. Amphotericin-B was de-escalated to Itraconazole maintenance therapy and then tapered in whom antifungal treatment was not initiated before testing. All the patients were followed up, re-tested after 10 days of therapy in some patients, and had shown negative results along with clinical improvement. The test showed good sensitivity and specificity. Conclusion: The rapid diagnosis of histoplasmosis using OIDx ICT is very helpful as a POCT (also in resource-limited settings) for initiating antifungal therapy in patients without having to wait for culture results.