ABSTRACT
This study was carried out to determine the airborne bacterial load and identify bacterial isolates in UNIBEN shuttle buses. Settle plate method was used for isolation. The isolates were identified using cultural, morphological and biochemical characteristics. The data was analyzed using Microsoft excel and descriptive statistics was used for interpretation of the data. The results showed that the mean airborne bacterial counts of pre-boarding/empty bus ranged from log10 2.24±0.07 cfu/m3 (front row), log10 2.54±0.11 cfu/m3 (middle row), log10 2.88±0.02 cfu/m3 (back row) to post-boarding with passengers, log10 3.66±0.01 cfu/m3 (front row), log10 3.72±0.01 cfu/m3 (middle row), log10 3.92±0.01 cfu/m3 (last row) in week one, ongoing from Ugbowo to Ring-road. In week two, the mean airborne bacterial counts of preboarding/empty bus ranged from log10 3.25±0.05 cfu/m3 (front row), log10 3.364±0.05 cfu/m3 (middle row), log10 3.19 ±0.02 cfu/m3 (last row) to post-boarding with passengers, log10 3.78±0.02 cfu/m3 (front row), log10 3.74±0.02 cfu/m3 (middle row), log10 3.85±0.04 cfu/m3 (last row) also going from Ugbowo to Ring-road. The bacterial counts were found to be higher in the last row for both week one and two. The airborne bacterial isolates identified include Proteus mirabilis, Bacillus mycoides, Enterococcus faecalis, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus, Pseudomonas aeruginosa. This study showed that Bacillus subtilis was the most occurring bacterium (30%), while Proteus mirabilis, Staphylococcus aureus, Enterococcus faecalis were the least occurring bacterial isolates (10%). Proteus mirabilis was the most resistant bacterium, with a multiple antibiotic resistance (MAR) index of 0.89, while Micrococcus luteus had MAR index of 0.11. This study has revealed that shuttle buses can serve as reservoirs for various bacterial species, including potentially harmful ones such as Bacillus. Enhancement of the ventilation systems in shuttle buses to promote better air circulation and filtration could also reduce the concentration of airborne bacteria.
