Piezoelectric cold atmospheric plasma inactivates dairy cattle bacteria and potentiates antibiotics in vitro

Wound infection remains a major challenge in animal health and welfare, particularly in the farm environment, where skin injuries are prone to microbial contamination. However, reliance on antibiotics increases the risks of antimicrobial resistance and drug residues in animal products. Therefore, developing effective non-antibiotic-based approaches for wound decontamination is critically important and an emerging priority. In the current study, the antimicrobial efficacy of cold atmospheric plasma (CAP) was assessed against Escherichia coli P4, Staphylococcus aureus M60, and Staphylococcus epidermidis NCTC 11047 inoculated onto a bovine collagen-elastin matrix that approximates dermal tissue. Bacterial survivors (log CFU/cm²) were quantified after CAP exposure of 30-180 s at 1-2 cm source distances, alongside mechanistic assessments (viability staining, intracellular reactive oxygen species (ROS), extracellular lactate dehydrogenase (LDH), adenosine triphosphate (ATP) leakage, and lipid peroxidation). At 1 cm exposure distance, CAP reduced viable counts below detection limit after 120 s across all strains; at 2 cm, significant but distance-attenuated reductions were maintained. CAP exposure decreased viability in a treatment time-dependent manner, increased intracellular ROS, and compromised membrane integrity, consistent with envelope permeabilisation. A brief 30-s pre-exposure enhanced antibiotic susceptibility, approximately halving MICs and reducing MBCs by up to 75% for oxytetracycline (engemycin) and enrofloxacin. These findings indicate that piezoelectric CAP provides broad antimicrobial activity and potentiates antibiotic efficacy, supporting translational potential for on-farm wound hygiene and antibiotic stewardship. KEY POINTS: • Piezoelectric CAP effectively reduces bacterial log CFU/cm². • Piezoelectric CAP compromises bacterial cell integrity and causes oxidative damage. • CAP-pretreated bacteria showed enhanced antibiotic susceptibility.