Abstract

Eggshell contamination by pathogenic and antimicrobial-resistant bacteria represents an important food-safety concern because eggs may serve as vehicles for bacterial transmission and exposure to resistant organisms. This study investigated the occurrence, phenotypic characteristics and antibiotic resistance profile of bacterial isolates recovered from eggshell surfaces of fresh eggs sold from ten retail outlets in Okada, Edo State, Nigeria. A total of 81 eggshell samples were examined using standard cultural, morphological and biochemical techniques, followed by antimicrobial susceptibility testing against ten antibiotics. No suspected Salmonella isolate was recovered, whereas seven suspected Escherichia isolates were detected at two outlets, giving an overall occurrence of 8.64%. Other isolates comprised Enterobacter (32.10%), Pseudomonas (32.10%), Proteus (11.11%), Klebsiella (9.88%) and Enterococcus (6.17%). Retail outlet was significantly associated with the occurrence of suspected Escherichia (χ² = 27.52, p = 0.001), Enterobacter (χ² = 23.39, p = 0.01) and Proteus (χ² = 72.79, p < 0.001), but not Klebsiella, Pseudomonas or Enterococcus. Resistance to cefuroxime, cefoxitin, ceftriaxone, ceftazidime, pefloxacin, gentamicin and streptomycin was 100%, while amoxicillin-clavulanic acid and ciprofloxacin resistance were 98.77% and 90.12%, respectively. Ofloxacin showed the lowest resistance (2.47%). Cochran’s Q test demonstrated significant differences in resistance across antibiotics (Q = 655.56, df = 9, p < 0.001). All isolates were multidrug-resistant, with an overall MAR index of 0.89. These findings indicate substantial bacterial contamination and a high antimicrobial resistance burden on retail eggshells, highlighting the need for improved poultry biosecurity, antimicrobial stewardship and hygienic egg handling as to safeguard public health.