P428 Evaluation of Galactomannan enzyme assay in non-hematological non-neutropenic ICU admitted patients for diagnosis of Invasive Pulmonary Aspergillosis as per EORTC criteria 2019

POSTER SESSION 3, SEPTEMBER 23, 2022, 12:30 PM - 1:30 PM: OBJECTIVE: The objective of this study was to evaluate galactomannan enzyme assay in non-hematological ICU patients for diagnosis of Invasive Pulmonary Aspergillosis as per EORTC criteria 2019. METHODS: Galactomannan detection in serum samples was performed by enzyme-linked immunosorbent assay in 138 patients with clinically suspected pulmonary aspergillosis between January 2012 and January 2019 in patients admitted to ICUs. Patients with hematological diseases or who underwent HSCT were excluded. Control group (n = 25) was selected from patients with no obvious immunosuppression, cough/dyspnea, or any other respiratory symptoms, etc admitted for elective surgeries from surgery wards. According to the criteria of the European Organization for Research and Treatment of Cancer/Mycoses Study Group revised in 2019, the patients were categorized as proven, probable, and possible IA. Galactomannan optical density indices ≥0.5 and ≥1 were analyzed with respect to clinical, radiological, and mycological evidence. RESULTS: Amongst 138 patients 2 fulfilled the criteria of proven IA, 78 were probable IA, and the rest (58) were grouped under possible IA. In the control group, the Galactomannan optical density index was ≤ 0.5. Receiver operating characteristic curve analysis showed the serum GM detection cutoff value was 0.91 (95% CI 0.885-0.973, P-value <.0001) with Youden index J = 0.78, its diagnostic value for pulmonary aspergillosis was optimized, and the sensitivity and specificity reached 83.75% and 94.83% respectively. Other cutoffs had high variance between sensitivity and specificity for the diagnosis of IPA. CONCLUSION: Our study highlights the usefulness of the serum GM antigen test in the early diagnosis of IA and suggests a GMI cutoff of 0.91 as it has the highest diagnostic accuracy. Also, we recommend that patients with a GM OD of ≥1.0 should be labeled as clear GM positive, whereas those with <0.5 OD should be labeled as GM negative, and in those with OD ranging from 0.5 to 1.0, repeat sampling from the patient is advisable. It seems more reasonable not to overtreat all patients with fever refractory to broad-spectrum antibiotics with antifungal agents, but rather to decide taking into account the serum GM antigen positivity. A negative GM antigen can curtail the usage of unwarranted antifungal therapy, especially in resource-poor country like India.