Microbiological Indoor Air Quality of Male Student Hostels in University of Benin, (Ugbowo Campus), Benin City, Nigeria.

Abstract

The microbial bioload of the indoor air environment in two (2) male student hostels ( Hall 3 and 4), University of Benin, Benin City were evaluated using the settle plate methods. The duration of the study was between September, 2011 and February, 2012. The antibiogram of the bacterial isolates was ascertained using the disc diffusion methods and molecular biological techniques to determine the presence of plasmids harbored by the bacterial isolates. The airborne heterotrophic bacterial counts in Hall 3 hostel between within the study duration ranged from 0.44 ± 0.5 × 10 3 cfu/m 3 to 8.6 ±1.2 × 10 3 cfu/m 3 in the morning and 0.35 ±0.4 × 10 3 cfu/m 3 to 9.8 ±0.6 × 10 3 cfu/m 3 in the afternoon. The airborne heterotrophic bacterial counts in Hall 4 hostel within the study duration ranged from 0.29± 0.5 × 10 3 cfu/m 3 to 2.7±
1.1 × 10 3 cfu/m 3 in the morning and 0.45 ± 0.7 × 10 3 cfu/m 3 to 2.4±3.1× 10 3 cfu/m 3 in the afternoon. The airborne heterotrophic fungal counts
in the morning and afternoon periods in Hall 3 hostel between September, 2011 and February, 2012 ranged from 0.32 ± 1.1 × 10 3 cfu/m 3 to
1.4 ± 0.6 × 10 3 cfu/m 3 and 0.38 ± 0.2 × 10 3 cfu/m 3 to 1.4 ± 0.8 × 10 3 cfu/m 3 respectively, while the airborne heterotrophic fungal counts in Hall
4 hostel between September, 2011 and February, 2012 ranged from 0.29 ± 0.4 × 10 3 cfu/m 3 to 1.9 ± 0.6 × 10 3 cfu/m 3 in the morning and 0.27
±.3 0 × 10 3 cfu/m 3 to 6.8± 2.0 × 10 3 cfu/m 3 in the afternoon. There was no significant difference (P > 0.05) between the morning and afternoon
airborne microbial counts observed in Hall 3 hostel obtained in the months of November, 2011 and February, 2012. The differences in the airborne bacterial counts obtained in Hall 3 and 4 hostels in the months of September, 2011, October, 2011 and January, 2012 were significant
(P < 0.05). Seven airborne bacterial and nine fungal isolates were obtained and identified from the halls of residence. Among the airborne bacterial isolates, Enterobacter aerogenes (64%) had the highest percentage frequency of occurrence and distribution, while S. epidermidis (14%) had the least percentage frequency of occurrence and distribution. While among the airborne fungal isolates, Aspergillus niger (94%), P. chrysogenum (94%) and Aspergillus veriscolor (98%) were the most frequently occurring isolates in the indoor air environment in Hall 3 and Hall 4. S. cerevisiae (5%) had the least percentage of occurrence and distribution amongst the fungal isolates. The bacterial isolates displayed resistance against cloxacillin and cefuroxine while Escherichia coli exhibited sensitivity against augumentin, ofloxacin, ciprofloxacin and erythromycin. Staphylococcus epidermidis, Klebsiella spp., Micrococcus spp. and Enterobacter aerogenes, all harboured plasmids, while no plasmid was detected for Bacillus spp. and Escherichia coli. The indoor air temperature recorded range from 27 0 C to 30 0 C in the morning and
28 0 C to 31 0 C in the afternoon for Hall 3, 27 0 C to 31 0 C in the morning and 28 0 C to 31 0 C in the afternoon for Hall 4. The relative humidity
ranged from 66% to 69% in the morning and 68% to 71% for Hall 3, while in Hall 4 it ranged from 68% to 70% in the morning and 68% to 71% in the afternoon. Anthropogenic activities were observed to positively influence the number and diversity of the indoor microbial population of the two hostels. Physical attributes such as temperature and relative humidity, of the indoor air in the respective hostels were poor, suggesting that the overall thermal comforts within these hostels were very poor.