Molecular identification of multidrug-resistant bacteria from eggshell surfaces in Nigeria: A growing threat to public health

Background: Eggs are an affordable dietary staple in Nigeria, yet they pose a potential public health risk when contaminated. This study assessed the prevalence of pathogenic bacteria and their antimicrobial resistance profiles on eggshells from markets in Lagos, Nigeria. Methods: A total of 51 table eggs were randomly sampled from poultry farms and supermarkets. Bacterial isolation and identification were conducted using standard microbiological methods, biochemical testing, and 16S rRNA gene sequencing. Antimicrobial susceptibility was evaluated using the Kirby-Bauer disc diffusion method. Results: All eggshell samples (100%) were contaminated with bacteria, with Staphylococcus aureus being the most prevalent organism. Other isolates included Escherichia coli, Bacillus cereus, and Salmonella typhimurium. Alarmingly, most isolates displayed complete resistance to first-line antibiotics like erythromycin and penicillin, while remaining susceptible to only gentamicin and ciprofloxacin. Conclusion: The widespread bacterial contamination and high levels of antimicrobial resistance observed on eggshells represent a significant public health threat. These findings underscore the urgent need for improved biosecurity in poultry production, enhanced hygiene in market environments, public education on food safety, and systematic surveillance under the One Health framework to mitigate risks associated with contaminated eggs.