author(s)
Monika Bhardwaj, Bhoj Raj Singh, Dharmendra Kumar Sinha, Vinodh Kumar OR, Prasanna Vadhana, Shiv Varan Singh and Archana Saraf

abstract
Excessive and indiscriminate use of antibiotics as therapeutic agent against many infectious diseases or as growth promoters lead to antimicrobial resistance to a greater extent. Antibiotic resistant bacteria are of public health importance and there is need to identify new compounds with antibacterial properties without any side effect. Herbal drugs offer an alternative approach to prevent the infectious diseases and hence can help in minimizing the antimicrobial resistance. In the present investigation, we have evaluated the in vitro antibacterial activity of carvacrol and its synergistic effects with antibiotics (Imipenem and colistin) against Escherichia coli isolates from faecal samples of various animal species by disc diffusion method. Total 430 E. coli isolates were screened for the carvacrol sensitivity and it was observed that all E. coli isolates were sensitive to carvacrol. The same isolates were screened for synergy between carvacrol and antibiotics (Imipenem and colistin). Total 14 (3.25%) E. coli isolates have shown synergy With Imipenem whereas none was synergistic with colistin. Among these, 6 (5.45%), 3 (2.6%), 2 (1.9%), (2.5%) and (4.1%) isolates were of pig, cattle, poultry, sheep and goat respectively. In conclusion, the carvacrol can be used as therapeutic agent against E. coli as alone or in combination with other antibiotics. Further work is needed to explore the antibacterial potential of carvacrol against another bacterial species as well as synergy with other antibiotics.