Research Article

Identification of Microorganisms Associated with Point of Sale (POS) Devices in Major Markets in Calabar

Abstract

Background: Point of Sale (POS) devices are widely used for electronic transactions in markets and commercial settings, yet their role as potential reservoirs for pathogenic microorganisms remains poorly studied, particularly in resource-limited environments. Aim: This study investigated the microbial contamination of POS devices in three major markets in Calabar, Watt Market, Marian Market, and Ikot Ishie Market. Method: A total of 20 POS devices (5 per market) were sampled by sterile swabbing of the keypad, touchscreen, and casing surfaces. Samples were transported in sterile peptone water and processed under aseptic conditions using Nutrient agar, MacConkey agar, Mannitol salt agar, Blood agar, Salmonella-Shigella agar, Thiocitrate bile salt agar, and Sabouraud dextrose agar. Bacterial isolates were identified by Gram staining, colony morphology,and standard biochemical tests, while antibiotic susceptibility was determined by disc diffusion according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Results: Total heterotrophic bacterial counts (THBC) on POS keypads ranged from 5.6 ± 0.1 to 7.8 ± 0.6 log10 CFU/cm² and 3.4 ± 0.3 to 5.0 ± 0.2 log10 CFU/cm², with a statistically significant increase in bacterial counts across all locations (p <0.05). Organisms isolated included Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and species of Bacillus, Pseudomonas, Proteus, Streptococcus, Salmonella, Shigella, Micrococcus, Vibrio and Klebsiella. Among Gram-positive isolates, Staphylococcus aureus recorded the highest frequency of occurrence (18.2%), while Micrococcus spp. had the highest frequency (17.2%) among all isolates; Vibrio spp.(1.4%) and Proteus sp. (2.8%) were the least frequently isolated. Gram-positive isolates showed the highest susceptibility to Gentamycin and the greatest resistance to Augmentin, while Gram-negative isolates were most susceptible to Ofloxacin and most resistant to Amoxicillin. Conclusion: These findings indicate that POS device user interfaces serve as potential sources of pathogenic and antibiotic-resistant organisms. Regular disinfection of POS devices and public awareness campaigns on personal hygiene practices after device use are recommended to reduce associated infection risks. 

Authors affiliation:

Ernest Chibuike Ohanu: Department of Medical Laboratory Science, University of Calabar, Cross River, Nigeria.
Chinyere Osondu-Anyanwu: Department of Science Laboratory Technology, University of Calabar, Cross River, Nigeria.
Imaobong Bassey Udoh: Department of Applied Behavior Analysis, Hopebridge Autism Therapy Centres, Georgia 30040, USA.
Juliet Osaremen Amedu: Department of Pharmacology, Basic Clinical Sciences, Pamo University of Medical Sciences, Port Harcourt, Rivers State, Nigeria.

How to Cite: E. C. Ohanu, C. Osondu-Anyanwu, I. B. Udoh and J. O. Legun. Identification of Microorganisms Associated with Point of Sale (POS) Devices in Major Markets in Calabar. Infectious, 3(2):1–6, 2026. https://doi.org/10.58612/infectious321