Introduction

Wide spread of antibiotic resistance remains a serious clinical problem, which stimulates studies for search of new methods for coping with drug resistance or renews interest in traditionally used and forgotten methods, such as treatment with antibacterial plant extracts and essential oils (EOs) (Ríos and Recio 2005; Fisher and Phillips 2009). Combined therapy is traditionally used to increase antimicrobial activity and reduce toxic effects of agents (Houghton 2009).

Thyme plant is used since ancient times to achieve healing, antiseptic fumigator, food preservation and other useful effects (Stahl-Biskup and Sáez 2002). Nowadays, Thymus vulgaris EO belongs to EOs with the most pronounced antimicrobial activity (Iten et al. 2009). It was shown to be active against many bacteria, viruses and fungi. High antimicrobial activity of thyme oil and its components, first of all thymol and carvacrol, was demonstrated against Staphylococcus aureus (Al-Bayati 2008; Soković et al. 2010; Lević et al. 2011), including methicillin-resistant isolates (Tohidpour et al. 2010), S. epidermidis (Soković et al. 2010), Enterococcus faecalis (Lević et al. 2011), Bacillus cereus (Al-Bayati 2008), Vibrio cholerae (Rattanachaikunsopon and Phumkhachorn 2010), Escherichia coli (Lević et al. 2011), Proteus mirabilis (Soković et al. 2010; Lević et al. 2011), P. vulgaris (Al-Bayati 2008), Pseudomonas aeruginosa (Soković et al. 2010), Salmonella enteritidis (Soković et al. 2010), S. choleraesuis (Lević et al. 2011), S. typhimurium (Soković et al. 2010), and other microorganisms.