Bacillus and Aspergillus Prevalence: an Investigation into the Indoor Microbial Quality of Built Environment at the University of Port Harcourt: Nigeria

Background: Inadequate indoor air quality poses significant challenges in school environments, stemming from factors such as overcrowded classrooms, insufficient ventilation, and substandard construction and maintenance practices. Bacterial and fungal contaminants in indoor air present serious health risks. Methods: This institutional-based cross-sectional study focused on selected learning halls to assess bacterial and fungal loads using the settle plate method. Analysis was accomplished through standard cultural methods. Nutrient agar and Potato Dextrose agar plates were exposed for 15 minutes to capture bacteria and fungi, respectively. Results: The study revealed a total bacterial load of 8300 CFU/m3 in the morning and 10400 CFU/m3 in the evening. The highest bacterial load occurred at MBS 25 (3200 CFU/m3 in the morning and 3700 CFU/m3 in the evening), while the lowest was recorded at the Arena (310 CFU/m3 in the morning and 990 CFU/m3 in the evening). Similarly, fungal loads varied, with the Arena recording the highest (620 CFU/m3 in the morning and 690 CFU/m3 in the evening) and the Faculty of Science Auditorium the lowest (310 CFU/m3 in the morning and 620 CFU/m3 in the evening). Bacillus spp. dominated among bacterial genera (25.9%), while Aspergillus spp. was the most prevalent fungal genus (41.7%). Other bacterial genera included Klebsiella, Staphylococcus, Enterococcus, E. coli, and Pseudomonas, while Penicillium and Candida were among the fungal genera. Conclusion: Mitigation strategies should target factors such as temperature, occupancy, and humidity to curb bacterial and fungal proliferation in indoor lecture halls, thus safeguarding the health of students and teachers in the University of Port Harcourt and similar educational institutions.