LARA SALVAGNO¹, SABINA SBLANO¹, GIUSEPPE FRACCHIOLLA¹, FILOMENA CORBO¹, MARIA LISA CLODOVEO², ANTONIO ROSATO¹*
*Corresponding author
1. Dipartimento di Farmacia – Scienze del Farmaco, Università degli Studi di Bari “Aldo Moro”, Bari, Italy
2. Dipartimento Interdisciplinare di Medicina, Università degli Studi di Bari “Aldo Moro”, Bari, Italy

Abstract

Essential oils (EOs) are known for their antimicrobial and anti-inflammatory properties and they could be used for treatment of several microbial infections in synergy with commercially available antibiotics. The synergistic effects between EOs and drugs would aim to reduce the side effects of antibiotic therapies, so,the goal of our research has been to highlight the potential synergistic effect between Mentha x piperita L. EO and three widely used antibiotics (Gentamicin, Oxacillin, Norfloxacin) on biofilm formation and growth. 

Gas chromatography hyphenated with mass spectrometry technique was employed to assess the EO chemical profile. 

The in vitro efficacy of the EO-Drug associations was evaluated against four different strains of Gram-positive bacteria, forming biofilms. Synergistic effects were tested using the chequerboard microdilution method and FIC index., All the combination of EO with antibiotics are able to produce a substantial inhibition of bacterial biofilms growth.

INTRODUCTION

Recently, the research for new antimicrobial agents has focused on natural compounds capable of inhibiting the formation and growth of bacterial biofilms (1). In fact, this is one of the causes of antibiotic resistance (AR), that is becoming a real growing evidence in the infections spreading (2). Recent reviews on this topic highlighted that among all natural products, EOs obtained from steam distillation of plants part have been extensively studied for their pharmacological activities and may be a promising alternative to prevent the biofilms formation in microbial infections (3-5). Nowadays, approximately 3,000 EOs are known and 300 of which are commercially available in the food, agronomic, sanitary and pharmaceutical areas (6). The Mentha piperita (MP) EO, derived from leaves or flowers of Mentha x piperita L. (Lamiaceae), can be utilized as food additive, or in cosmetics and pharmaceutical preparations and it is widely used in aromatherapy practice, too (7). Moreover, it shows an interesting antiviral, antifungal, antibacterial and antioxidant activityin vitro depending mostly on its chemical profile (6, 7). Since the chemic ...