Antimicrobial and antibiofilm effects of clove tea on bacteria isolated from kitchen food-contact surfaces

Background This study aimed to investigate the antimicrobial and antibiofilm effects of clove tea against biofilm-forming microorganisms likely to be present on food-contact surfaces after routine cleaning in kitchens and against mature biofilms. Swab samples were collected after routine cleaning from equipment and countertop surfaces in different areas of a ready-meal kitchen, and the isolates obtained were identified using cultural methods. The biofilm-forming properties of the isolates were determined using Congo red agar and the crystal violet method. The effects of clove tea prepared by brewing at different concentrations on planktonic cells and bacteria associated with mature biofilms of Staphylococcus aureus isolates were investigated by culturable cell enumeration and the crystal violet method. Results A total of 22 isolates were obtained from 50 different sampling points in different areas of the kitchen. These isolates were identified as Escherichia coli and S.aureus . Of the 22 isolates, 15 were determined to be biofilm-positive. The effect of clove tea on bacterial viability and biofilm formation was observed to be concentration-dependent. Clove tea exhibited antimicrobial activity against the bacteria, with a mean minimum inhibitory concentration (MIC) value of 15% and a mean minimum bactericidal concentration (MBC) value of 19.33%. Although increased exposure time also affected bacterial viability, concentration was found to be an important factor in determining the efficacy. The increases observed in the OD570 values measured using the crystal violet method at high tea concentrations were determined to require evaluation together with viable bacterial counts, as the color of the tea itself and/or its components may interfere with the measurements. Conclusions In conclusion, clove tea was found to have potential as an additional application aimed at reducing biofilm-associated bacteria that may remain on kitchen surfaces after cleaning, rather than as a replacement for routine cleaning procedures. Due to its ease of preparation and natural origin, clove tea may be considered a potential alternative worthy of further investigation for supporting microbial safety on kitchen surfaces. Clinical trial number Not applicable.