Antibacterial effects of lidocaine and adrenaline

The most commonly used local anaesthetics (LAs) for postoperative analgesia and surgical anaesthesia are lidocaine and bupivacaine. Adrenaline is a vasopressor agent, which is widely used in anaesthesia for many purposes. This study aims to determine the antibacterial efficacy of lidocaine, mupirocin, adrenaline, and lidocaine + adrenaline combination. In our study, the in vitro antimicrobial effect of 1 mL of sterile saline, 20 mg/mL mupirocin, 20 mg/mL lidocaine, 1 mg/mL adrenaline, and 20 mg/mL lidocaine and adrenaline were tested against Staphylococcus aureus American-type culture collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922, classified as Group C (control), Group M (mupirocin), Group L (lidocaine), Group A (adrenaline), and Group LA (lidocaine+adrenaline), respectively. S. aureus ATCC 29213, P. aeruginosa ATCC 27853, and E. coli ATCC 25922 were cultured on Mueller-Hinton agar (Oxoid, UK) plates for 18 to 24 hours at 37°C. Colonies from these plates were suspended in sterile saline, and a 0.5 McFarland turbidity standard suspension (corresponding to 1.5 × 10⁸ CFU/mL) of each isolate was prepared. In terms of inhibition zone diameters, S. aureus ATCC 29213 values obtained after 12 and 24 hours of incubation were significantly different between groups (P < .001). According to inhibition zone diameters, Group M > Group LA > Group L > Group C = Group A. P. Aeruginosa ATCC 27853 values obtained after 12 and 24 hours of incubation were significantly different between groups (P < .001). According to inhibition zone diameters, Group M > Group LA > Group L = Group C = Group A. E. coli ATCC 25922 values obtained after 12 and 24 hours of incubation were significantly different between groups (P < .001). According to inhibition zone diameters, Group M > Group LA > Group L > Group C = Group A. It is known that LAs have antimicrobial effect potential in addition to their anaesthetic, analgesic, antiarrhythmic, and anti-inflammatory effects. There are also studies showing the antimicrobial effects of vasopressor agents, which are frequently used, particularly in intensive care unit (ICUs). However, it has been observed in the present study that adrenaline alone did not have any antimicrobial effect. Adrenaline, when used in combination with lidocaine, provides a stronger and broad-spectrum antimicrobial activity, suggesting that its combined use in proper indications will be clinically significant. Because the prevention and treatment of wound infections make a positive contribution to wound healing, the potential of antimicrobial effect of LAs can provide successful results in the prevention and treatment of ICU and wound infections. Thus, an important contribution can be made in terms of reducing the costs of antibacterial treatment and reducing morbidity.