Assessment of bacteria associated with naira notes

Abstract

Background: Microbial transmission on the surface of any currency note can either be through direct (hand to hand contact) or indirect (food or other inanimate objects) means. Objectives: This study was designed to assess and compare  microbial load between two currencies (N100 and N1000 naira note). Methods: The identification of bacterial species was achieved through gram staining, microscopic analysis and biochemical test (catalase, coagulase, urease, citrate, indole and motility test). Results: Out of 10 samples, 8 samples were found to be more contaminated by different species of bacteria. N100 notes harbor the highest bacteria load, while N1000 notes harbor the least bacterial load. This study also shows that, Streptococcus pyrogenes was the least encountered as compared to Staphylococcus aureus. Most of the naira notes were wrinkled  and dirty  especially the N100 naira notes. The bacterial counts were generally high: ranging from 2.0 to 6.2 × 10⁵ cfu/cm². The N100 notes harbor the highest bacterial load (average of 6.2 × 10⁵ cfu/cm²) while N1000 notes had the least (2.0 × 10⁵ cfu/cm²).  The occurrence of bacteria isolates on one hundred (N100) notes, four species: Escherichia coli, Staphylococcus aureus, pseudomonas aeruginosa, Streptococcus pyrogenes were isolated. The occurrence of bacterial isolated on one thousand (N1000) notes, three bacterial species: Escherichia coli, Staphylococcus aureus, Pseudomonas aeroginosa. were isolated. The occurrence of the bacterial isolates, i.e Streptococcus pyrogenes was the least encountered (20%) while Staphylococcus aureus was the most encountered (70%). Conclusions: The study indicated  a high concentration of bacteria on one hundred (N100) notes compared to one thousand (N1000) naira notes with 65% and 35% respectively.

Keywords: Bacterial contamination, Naira notes, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes