P426 Interleukins—a non-invasive biomarker for invasive fungal sinusitis
Authors: Kadhirvelu Hemanth Kumar , T. Premamalini , Kumar Kennedy , Kindo Anupma Jyoti 
Published: September 2022

Abstract

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM

Objectives
Invasive fungal infection is estimated to cause around 1.5 million deaths each year. But the true burden is estimated to be even more due to the lack of reliable diagnostic methods. Invasive fungal sinusitis (IFS) is the emerging infection leading to high morbidity and mortality (80%). Both clinical suspicion and reliable diagnostic tests available to diagnose an IFS are less. As a result, most patients are diagnosed only in the later stages. Nasal swabs for IFS are less useful and the most appropriate sample for the diagnosis will be the deep tissues involved, which are obtained after an invasive procedure. The gold standard test for diagnosis of IFS is the isolation of fungus in culture media but its sensitivity is ˂50%. Hence a non-invasive procedure to help in the diagnosis of invasive fungal sinusitis is needed. The role of Interleukins (IL) in fungal infections, especially IL-10 and IL-17 has been documented in various research in the past. Hence this research was carried out to study the role of IL-10 and IL-17 in invasive and non-invasive fungal sinusitis (NIFS).

Methods
The study was carried out in the Department of Microbiology, SRIHER, Chennai. A total of 60 samples collected from patients suspected to have fungal sinusitis and sent to the laboratory for fungal culture were considered for the study. All the samples which grew fungus were categorized as IFS and NIFS. ELISA was performed with the serum samples of patients for IL-10 and IL-17 based on manufacturer's instruction (Human IL-10 ELISA Kit, Thermofisher and Human IL-17 ELISA Kit, Thermofisher), and reading is taken in a spectrophotometer (Thermo Fisher Scientific).

Results
Among the 60 serum samples tested, 30 were categorized as IFS and the rest as NIFS. A total of 90% (n = 27/30) of IFS patients expressed interleukins in serum samples whereas none of the NIFS expressed both the interleukins tested. Among IFS, IL-10 was seen in 63.3% (n = 19/30) patients, IL-17 in 46.7% (n = 14/30) patients and 20% (n = 6/30) patients expressing both IL-10 and IL-17. In IFS the mean value of IL-10 and IL-17 were 6.657 and 4.259 respectively. Among the 30 IFS, 13 were positive for COVID-19. IL-17 was expressed in 84.6% (n = 11/13) of COVID-19 positive IFS patients. But only 23.1% (n = 3/13) of COVID-19 positive IFS patients expressed IL-10. A total of 15.4% (n = 2/13) of the COVID-19 positive patients did not express any interleukins. Surprisingly the expression of IL-10 among COVID-19 negative IFS was 94.1% (n = 16/17). The specificity of both IL-10 and IL-17 was 100% in the case of IFS.

Conclusion
Thus, interleukins look to be a promising biomarker for IFS. Further studies will help in establishing interleukins as a potential non-invasive biomarker for IFS. IL-17 can be used as a biomarker for COVID-19 patients suspected to have IFS. Also looking for more than one cytokine preferably a combination of IL-10 and IL-17 should be done in patients with NIFS, which will help in the early prediction of patients progressing into IFS and can be managed accordingly.