Effect of nasal carriage ofBacillusspecies on COVID-19 severity: A cross-sectional study

Abstract

Intranasal sprays containing Bacillus species are being researched for treating viral respiratory tract infections. The aim of this study was to assess the relationship between the nasal carriage ofBacillusand COVID-19 severity. This was a cross-sectional study that collected nasopharyngeal samples from adults 18 years and above visiting two COVID-19 testing centers in Lagos, Nigeria between September 2020 and September 2021. Bacillus species were cultured from the respiratory samples and confirmed using molecular methods. The dependent variable was COVID-19 status classified as negative, asymptomatic, mild, or severe. The independent variable was the nasal carriage of Bacillus species. Multinomial regression analysis was done to determine the association between nasal carriage of Bacillus and COVID-19 severity after adjusting for age, sex, and co-morbidity status. About 388 participants were included in the study with a mean (standard deviation) age of 40.05 (13.563) years. The majority (61.1%) of the participants were male, 100 (25.8%) had severe COVID-19, 130 (33.5%) had pre-existing comorbidity, and 76 (19.6%) had Bacillus cultured from their nasopharyngeal specimen. Bacillus species presence was significantly associated with higher odds of severe COVID-19 compared to having a negative COVID-19 status. However, the presence of Bacillus species was significantly associated with lower odds of severe COVID-19 compared to having a mild COVID-19 status. The study suggests that nasal carriage of Bacillus species may substantially impact the clinical course of COVID-19. This study supports the exploration ofBacillusspecies in the prevention and management of viral respiratory tract infections.