The antibacterial mechanism of carvacrol and thymol against Escherichia coli.

AIMS: To investigate the antibacterial mechanism of carvacrol and thymol against Escherichia coli. METHODS AND RESULTS: The time-kill curve results showed that carvacrol and thymol at 200 mg l(-1) could inhibit the growth of E. coli. Flow cytometry and fluorescent dyes were used to explore the effect of two components on membrane permeability and membrane potential. In membrane permeability experiment, the mean fluorescence intensity of cells treated with 200 mg l(-1) carvacrol or thymol were lower than nonexposed cells. The ratio of red to green fluorescence intensity of DiOC2(3) reflected the change of membrane potential. Carvacrol and thymol at 200 mg l(-1) caused the ratio of red/green decreasing from 0.42 of control to 0.08 and 0.07, respectively. CONCLUSIONS: Carvacrol and thymol had desired antimicrobial effect on E. coli. The antibacterial effects were attributed to their ability to permeabilize and depolarize the cytoplasmic membrane. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed the potential use of flow cytometry as a suitable method to investigate the mode of antibacterial action of essential oil components.

Barrett's esophagus in a child with de Lange syndrome: report of one case.

Barrett's esophagus, a premalignant condition, is recognized as stratified squamous epithelium of the esophagus substituted by columnar epithelium. The risk factors for development of Barrett's esophagus include frequent gastroesophageal reflux, esophageal stricture, male sex and mental retardation, but there is no report of Barrett's esophagus in children with de Lange syndrome. We report a 7-year-old boy who was diagnosed as de Lange syndrome shortly after birth and had gastroesophageal reflux since early infancy. Upper gastrointestinal endoscopic examination revealed a cauliflower-like mass and a pink-red velvety mass over the lower third of the esophagus. Biopsy showed goblet cells metaplasia, confirming Barrett's esophagus. We suggest surveillance of Barrett's esophagus could be done ahead of schedule in children with long-standing gastroesophageal reflux or with de Lange syndrome.