Journal of Disease and Global Health

Microorganisms are ubiquitous, and laboratory equipment can harbour pathogens, compromising experiment reliability and posing health risks. In developing countries like Nigeria, limited resources and poor biosafety practices exacerbate contamination risks. This study aims to isolate and identify microbial contaminants on selected biology laboratory equipment (autoclave, refrigerator, incubator, and hot air oven) to evaluate their occurrence, diversity, and associated risks in academic settings, particularly within the Nigerian context. This study was carried out in the Biology Laboratory of Rivers State University, Port Harcourt, Nigeria. A total of 8 swab samples were taken with the aid of a sterile cotton swab stick pre-moistened in sterile normal saline. Samples were subjected to standard microbiological techniques, including serial dilution, culturing on selective media, Gram staining, and biochemical characterisation of isolates, while fungi were identified microscopically with lacto-phenol cotton blue staining. The total colony counts varied across equipment and surfaces. The Total Heterotrophic Bacterial Count (THBC) ranged from 2.7 × 10⁵ to 4.2 × 10⁵ CFU/ml, the Total Coliform Count (TCC) ranged from 1.1 × 10³ to 3.6 × 10³ CFU/ml, the Total Staphylococcal Count (TSC) ranged from 1.5 × 10³ to 4.5 × 10³ CFU/ml, while the Total Fungal Load (THFL) ranged from 1.2 × 10² to 4.0 × 10² CFU/ml. The refrigerator recorded the highest bacterial load, while the incubator recorded the highest fungal load. In most cases, external surfaces were more contaminated than internal ones, except in the refrigerator, where the interior was slightly more contaminated. The microbial analysis revealed diverse bacteria, including Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus spp., Listeria monocytogenes, Proteus mirabilis, and Acinetobacter baumannii, as well as fungi such as Aspergillus niger, Aspergillus flavus, Penicillium spp., Rhizopus spp., Mucor spp., Fusarium spp., Cladosporium spp., Alternaria alternata, and Candida albicans. The persistence of spore-formers (Bacillus spp.) even in sterilising equipment underscores gaps in sterilisation efficiency. This study demonstrates that laboratory equipment, if not properly maintained, can serve as reservoirs of pathogenic microorganisms. Regular disinfection, periodic servicing of sterilising equipment, and strict adherence to biosafety practices are recommended to minimise laboratory-acquired infections and safeguard research integrity.