Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry

SIMPLE SUMMARY: The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against Escherichia coli (E. coli) strains isolated from poultry with colibacillosis. One hundred and seventeen strains isolated from laying hens, broilers, and turkeys and belonging to serogroups O78, O2, O128, O139, which are often responsible for avian colibacillosis, were analyzed. The minimum inhibitory concentration (MIC)(50) and MIC(90) of CEO were evaluated by testing each bacterial strain at cell densities of 10(8) CFU/mL and 10(6) CFU/mL, respectively. At 10(8) CFU/mL, MIC(50) and MIC(90) were, respectively, 0.4 and 0.5 µL/mL for the strains from laying hens, and 0.5 and 0.6 µL/mL for strains from turkeys. MIC(50) and MIC(90) corresponded to 0.5 µL/mL for the strains isolated from broilers. Grouping the strains according to the serogroup, MIC(50) and MIC(90) were 0.4 and 0.5 µL/mL for strains belonging to serogroups O78, O2, and O128. A concentration of 0.5 µL/mL of CEO corresponded to both MIC(50) and MIC(90) for strains belonging to serogroup O139. MIC(50) and MIC(90) of CEO were 0.3 and 0.4 µL/mL respectively for strains tested at the cell density of 10(6) CFU/mL, regardless of the bird species of origin. According to the serogroups, MIC(50) and MIC(90) were 0.3 and 0.4 µL/mL for strains belonging to serogroups O78 and O2. A concentration of 0.4 µL/mL of CEO corresponded both to MIC(50) and MIC(90) for strains belonging to serogroups O139 and O128. This study showed that CEO has effective antibacterial activity against pathogenic E. coli in poultry. ABSTRACT: Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC(50) and MIC(90) of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 10(8) and 10(6) CFU/mL. At the cell density of 10(8) CFU/mL, MIC(50) and MIC(90) were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 10(6) CFU/mL, MIC(50) and MIC(90) were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC(50) and MIC(90) for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.