Detection and profiling of antibiotic resistance among bacteria isolates from new and unused styrofoam and single use plastics sold in Orlu, Imo State Nigeria

Background: Many ready to eat foods are packaged with single use plastics and Styrofoam that are rarely cleaned, washed or sterilized before use by food vendors, at home and public events. These surfaces harbour bacteria which contaminate the food and result in food-borne diseases when consumed along with the food by susceptible individuals, leading to illnesses and possibly death. This study assessed the status of bacterial contamination and antibiotic susceptibility profile of bacteria isolates from new and unused Styrofoam and single use plastics sold in Orlu, Imo State Nigeria.

Methodology: A total of thirty (30) Single Use Plastics bought from random outlets in Orlu international market were analyzed using standard microbiological techniques for bacterial isolation and identification, followed by antibiotic susceptibility testing using the disk diffusion method.

Result: The total bacterial count ranged from 1.1 X 10⁵ to 9.0 x 10⁵ CFU/ml. Six bacterial genera were identified, with Staphylococcus aureus being the most prevalent 70 (32.4%), followed by Clostridium sp. 46(21.3%), Pseudomonas aeruginosa 37(17.1%), Bacillus sp. 35(16.2%), Streptococcus sp. 20(9.3%), and Escherichia coli 8(3.7%). Antibiotic susceptibility was evaluated against seven commonly used antibiotics: Amikacin, Bacitracin, Ceftazidime, Clindamycin, Gentamicin, Mupirocin, and Ofloxacin. Amikacin demonstrated the highest effectiveness with near-complete susceptibility across most isolates, while variable resistance patterns were observed for other antibiotics. Notable resistance was found against Bacitracin (15.4-50%) and Ofloxacin (8.3-33.3%) across different bacterial species. A Multiple Antibiotic Resistance Index (MARI) analysis revealed high levels of multi-drug resistance, with values ranging from 0.42 to 0.71, being highest in Clostridium sp. isolates from both Styrofoam and single-use plastics. All bacterial isolates exhibited MARI values exceeding 0.2, indicating high-risk sources with significant antibiotic exposure.

Conclusion: The presence of these multi-drug-resistant strains on unused food-contact materials raises significant public health concerns, particularly given the widespread use of these materials in food packaging and service industries. These findings emphasize the need for enhanced quality control measures during manufacturing and storage, stricter hygiene protocols, and regular monitoring of antibiotic resistance patterns in food-contact and packaging materials.