Microbiological Assessment of Laboratory Workbench Surfaces

Abstract

The microbiological assessment of twenty laboratory workbench surfaces within University of Ilorin was carried out. Surface swabbing method was used for the collection of the sample over an area of 25cm by 25cm of the laboratory workbench surfaces. Antimicrobial Susceptibility test was carried on the bacterial isolates using the agar disk diffusion method. The bacterial count ranged from 4.0 x 10² - 2.5 x 10⁵cfu/ml per 25 x 25 cm² of the surface area while the fungal count ranged from 2.0 x 10² - 1.6 x 10⁵cfu/ml of the surface area. A total number of six bacteria and six fungi were isolated. The bacteria isolated were Staphylococcus auricularis, Staphylococcus aureus, Aerococcus sp., Micrococcus sp., Micrococcus kristinae, and Pseudomonas aeruginosa while fungi isolated were Verticillium lateritium, Candida sp., Cladosporium sphaerospermum, Alternaria alternata, Rhodotula sp., and Scopulariopsis sp. The results of antibiotic susceptibility test showed that all the Gram positive bacteria were sensitive to gentamicin while the only Gram negative bacterium, isolated Pseudomonas aeruginosa, and was sensitive to nitrofurantoin alone. It is concluded from this study that the laboratory workbench surfaces contain viable bacteria and fungi, some of which are known to be pathogenic. It is recommended that the laboratory workbenches should be disinfected regularly.