Microbiological Analysis, Antibiogram and Different Washing Treatments of Reusable Plastic Bottles Used in Packaging Food Products Within Ikot Ekpene Metropolis

Abstract

Traditional foods such as fermented cereal drinks, locally brewed beverages, cooking oils, and thick sauces are commonly stored in reusable plastic bottles that support rapid bacterial growth. This study examined 80 reusable plastic bottles used for packaging these products using standard microbiological methods. Inner surfaces were swabbed with sterile nutrient broth, suspended in 9 ml saline, serially diluted, and plated on Nutrient Agar, MacConkey Agar, and Sabouraud Dextrose Agar before incubation at 37 °C for 24 – 48 hours. All samples were contaminated. Unwashed bottles had the highest total bacterial counts of 1.1 × 10⁴ – 9.5 × 10⁴ CFU/ml, while washing with sterile water, soapy hot water (>60 ⁰C, and 3 % hydrogen peroxide reduced counts to 1.0 – 7.0× 10⁴, 1.0 – 5.0 × 10⁴, and 1.0 – 1.2 × 10⁴ CFU/ml, respectively, with 3 % hydrogen peroxide being most effective.  Bacterial solates included Streptococcus spp., Klebsiella spp., Escherichia coli, Staphylococcus aureus, Bacillus spp., and Pseudomonas aeruginosa. Fungal counts in unwashed and sterile water-washed bottles ranged from 0.0 – 3.0 × 10⁴ CFU/ml, dominated by Aspergillus and Penicillium   spp., but no fungi were recovered after hot soapy water or hydrogen peroxide treatment. Antibiotic susceptibility testing showed that S. aureus, Streptococcus spp., Bacillus spp., and E. coli were sensitive to agents including Ciprofloxacin, Streptomycin, Gentamicin, Levofloxacin, and Ampiclox, while several isolates were resistant to others. The findings highlight significant microbial risks from reused bottles and the need for effective decontamination before reuse.