Bacteriological assessments of indoor air in the staff quarters of a tertiary institution in Benin City, Nigeria

Abstract

Indoor air contains large number of airborne microorganisms such as bacteria and fungi and their estimation is important for use as index of cleanliness for any particular environment and to determine the relation they bear on human health. This study was aimed at determining the bacteriological air quality of the living rooms in some selected Staff Quarters in University of Benin and University of Benin Teaching Hospital. The airborne bacterial loads of indoor air in the living rooms of Twelve (12) Staff Quarters in University of Benin and University of Benin Teaching Hospital both in Benin City were determined using the Settle Plate methods. The houses were categorized as Apartment 1 which represents University of Benin Junior Staff Quarters (JSQ), Apartment 2 which represents University of Benin Teaching Hospital Quarters, and Apartment 3 which represents University of Benin Senior Staff Quarters (SSQ). The living rooms were sampled twice a month between April, 2017 and September, 2017. The airborne samples were studied using standard microbiological methods and Polymerase Chain Reaction and 16S rRNA techniques were used for the gene sequencing. The antibiotic susceptibility pattern and plasmid profile of the characterized airborne bacterial isolates were evaluated using spread plate and agarose gel electrophoresis methods. The temperature and relative humidity of the indoor air environment in the sampled areas in the living rooms were determined using the thermometer and hygrometer respectively. The mean indoor temperature and relative humidity for Apartments 1, 2 and 3 ranged from 26.10 ± 1.190C to 31.20 ± 0.870C and 81 ± 2.70% to 87 ± 1.89% respectively. The mean indoor airborne bacterial counts in Apartment 1 and Apartment 3 ranged between 1.00 x 103 ± 0cfu/m3 to 4.42 x 103 ± 1.42cfu/m3 and 1.09 x 103 ± 0.09cfu/m3 to 5.17 x 103 ± 3.17cfu/m3 respectively. In Apartment 2, the counts ranged from 1.00 x 103 ± 0.00cfu/m3 to 6.99 x 103 ± 4.69cfu/m3. The difference in the airborne bacterial counts obtained in the morning and afternoon period of study in Apartment 1 was statistically significant (P<0.05) while Apartments 2 and 3 showed no significant differences respectively (P>0.05). Ten airborne bacterial isolates were characterized, further characterization by molecular techniques, confirmed them to be identified as Staphylococcus aureus strain S33 R, Bacillus subtilis subsp. strain 168, Oceanobacillus manasiensis strain YD3-56, Streptomyces vietnamensis strain GIM4.0001, Actinosynnema pretiosum strain C-15003, Micrococcus caseolyticus strain 235, Ornithinibacillus composti strain GSS05 and Bacillus ectoiniformans strain NE-14. General and personal hygienic practices are important for healthy living, and living rooms used for close contact interactions and good ventilation.