In Vitro and In Vivo Comparison of Changes in Antibiotics Susceptibility of E. coli and Chicken’s Intestinal Flora after Exposure to Amoxicillin or Thymol

Abstract

<jats:p>This study aims at verifying, <jats:italic>in vitro</jats:italic>, the extent to which the use of amoxicillin or thymol induces the selection of resistant bacteria and at evaluating <jats:italic>in vivo</jats:italic> their effects on the development of antimicrobial resistance in the intestinal flora of poultry. <jats:italic>E. coli</jats:italic> strain was subcultured on agar plates containing increasing concentrations of either amoxicillin or thymol. Thereafter, minimal inhibitory concentrations (MICs) of thymol, amoxicillin, and two other antibiotics, tylosin and colistin, were determined using the microdilution method. Groups of chicks were subjected to a 2-week regime of either amoxicillin or thymol added to their drinking water. During the treatment with either thymol or amoxicillin, the total aerobic mesophilic flora (TAMF) was counted on thymol-gradient plates or amoxicillin-gradient plates and the MICs of antibiotics and thymol for <jats:italic>E. coli</jats:italic> isolates were determined. The <jats:italic>in vitro</jats:italic> test showed that for <jats:italic>E. coli</jats:italic>, which had been serially subcultured on increasing concentrations of amoxicillin, a 32-fold increase in MIC values for amoxicillin and a 4-fold increase for colistin and tylosin were noted. However, the MIC of thymol for this strain remained constant. For the <jats:italic>E. coli</jats:italic>, which had been serially subcultured on increasing concentrations of thymol, no change in the MIC values for antibiotics and thymol was observed. The <jats:italic>in vivo</jats:italic> test confirmed the <jats:italic>in vitro</jats:italic> one. It demonstrated that exposure to amoxicillin induced a selection of antimicrobial resistance in TAMF and intestinal <jats:italic>E. coli</jats:italic>, whereas exposure to thymol did not. The results showed that the group receiving thymol had a lower consumption index compared to the other groups. This study demonstrates the feasibility of this natural product as an alternative solution to the current use of antibiotics in poultry farming.</jats:p>

A Pilot Study on the Effect of Thyme Microemulsion Compared with Antibiotic as Treatment of Salmonella Enteritidis in Broiler

“…Thymol was found to have a positive effect on significantly reducing the number of antibiotic-resistant bacteria, which may make it a good alternative to antibiotics. This natural product could be an efficient alternative that would have positive effect to fight antimicrobial resistance that is observed in human which originates from the administering of antibiotics to farm animals [ 10 , 35 , 36 ].…”

Efficient Fermentative Production of d-Alanine and Other d-Amino Acids by Metabolically Engineered Corynebacterium glutamicum

“…The bilayered linear gradient agar plate was prepared by initially pouring a portion of dissolved CGXII agar medium containing 50 g/L d -Ala into a Petri plate and allowing it to solidify while held in an inclined position. Subsequently, a second portion of agar medium without d -Ala was poured and solidified while the plate was kept level. , The cells of various microorganisms, including C. glutamicum ATCC 13032, Bacillus subtilis 168, E.…”

“…Subsequently, a second portion of agar medium without D-Ala was poured and solidified while the plate was kept level. 8,9…”

“…Subsequently, a second portion of agar medium without D-Ala was poured and solidified while the plate was kept level. 8,9 and Yarrowia lipolytica Po 1d, were inoculated onto the gradient agar plate to evaluate their tolerance toward D-Ala and determine the minimal inhibitory concentrations (MICs) of this compound. The L-Ala oxidase and deaminase activities were assessed using the method proposed by Massad et al 10 Specifically, E. coli cells containing RoLAAO and PmLAAD expression plasmids were individually cultured on LB solid medium supplemented with 1 g/L L-Ala and 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG).…”