Escherichia. coli O157:H7 (E. coli O157:H7) is a gram-negative bacteria that has been known for the main cause of food-borne disease and acute hemorrhagic diarrhea in various hosts including humans.
E. coli O157:H7 is transmitted by the fecal-oral route, and most illness has been associated with eating undercooked, contaminated ground beef or pork or eating contaminated vegetables. Multidrug-resistant strain of E. coli O157:H7 has increased over the last several decades and recently have caused more serious problems in public health.
The present study was investigated the antibacterial effect of Flos Syzygii Aromatici methanolic extracts (FSAE) and the therapeutic effect of FSAE for E. coli O157:H7 infection in mice.
In the antibacterial effect of FSAE against E. coli O157:H7, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 0.269 and 1.075 mg/mL, respectively. On 24 hours after incubation of E. coli O157:H7, FSAE at the dose of 0.269 (p<0.05), 0.538 (p<0.001) and 1.075 mg/mL (p<0.001) significantly inhibited the growth of E. coli O157:H7 compared with the control group.
For 7 days after single challenge with E. coli O157:H7, forty female ICR mice were divided into four experimental groups and orally administered with saline, 0.538 (2×MIC), 1.075 (MBC) and 2.15 (2×MBC) mg/mL of FSAE, respectively. On the 3rd day, the number of E. coli O157:H7 in mouse feces was significantly decreased by administration of 1.075 (p<0.05) and 2.15 (p<0.01) mg/mL of FSAE. On the 7th day-after, the number of E. coli O157:H7 in mouse feces was significantly decreased by administration of 0.539 (p<0.05), 1.075 (p<0.001) and 2.15 (p<0.001) mg/mL of FSAE. The results of this study indicate that FSAE has a potential therapeutic effect for E. coli O157:H7 infection in mice.
In the hematological and blood biochemical analyses, all parameters in groups treated with FSAE (0.538, 1.075 and 2.15 mg/mL) were not significantly different compared to those of the control group. Thus, 7-day oral administration of FSAE does not affect the hematological and blood biochemical parameters.
In conclusion, this study suggests that it is very safe to administer the FSAE at the dose of 2.15 mg/mL per day, and it is also expected that the FSAE can be used for the substitution of antibiotics and chemical food additives against E. coli O157:H7 infection or food contamination.