phenylalanine-arginine-beta-naphthylamide and epigallocatechin-gallate

Pseudomonas aeruginosa is a notorious multidrug resistant nosocomial pathogen. An efflux pump (MexAB-OprM) is the main contributor to the multidrug resistance in clinical isolates of P. aeruginosa. Epigallocatechin-3-gallate (EGCG), a polyphenolic compound extracted from green tea, exhibits antibacterial activity. It is unclear that molecular details of the antibacterial activity of EGCG, EGCG-effect on antibiotic susceptibility, and clinical relevance of EGCG in bacteria.. This study aimed to determine the roles of the efflux pump and an efflux pump inhibitor (phenylalanine-arginine β-naphthylamide; PAβN) in the antibacterial activity of EGCG and the EGCG-effect on antibiotic susceptibility.. Twenty-two multidrug resistant clinical isolates of P. aeruginosa and a wild type P. aeruginosa PAO1 were used to determine antibacterial activity of EGCG and EGCG-effect on antibiotic susceptibility. An efflux pump (MexAB-OPrM) mutant strain, its complemented strain carrying an intact mexAB-oprM, and their parental strain were used to determine roles of MexAB-OprM in the antibacterial activity of EGCG and EGCG-mediated antibiotic susceptibility. PAβN was also used to evaluate EGCG as a possible efflux pump inhibitor.. EGCG inhibited cellular growth and killed 100% of cells at 64-512 µg/ml and at 256-1024 µg/ml, respectively, in all tested 22 clinical isolates including the wild type strain. A subinhibitory concentration of EGCG significantly enhanced susceptibility to antibiotics, unexceptionally to chloramphenicol and tetracyclines (≥4-fold) of the clinical isolates. Both the antibacterial activity of EGCG and the EGCG-mediated antibiotic susceptibility were enhanced more in the efflux pump mutant strain (mexB::Gm) than the parental strain, suggesting additionally accumulated-EGCG produced the more antibacterial activity in the mutant strain. EGCG was synergistically interacted with PAβN with enhancing susceptibility to all tested antibiotics (up to >500-fold) at higher levels than either EGCG alone or PAβN alone, suggesting EGCG may also inhibit the efflux pump with additional accumulation of the antibiotics.. The results demonstrate that EGCG exhibits antibacterial activity and enhances antibiotic effects against clinical isolates of P. aeruginosa. EGCG may inhibit the efflux pump (MexAB-OprM) through which are associated with the antibacterial activity of EGCG and the EGCG-mediated antibiotic susceptibility in P. aeruginosa.

Topics: Anti-Bacterial Agents; Bacterial Outer Membrane Proteins; Catechin; Dipeptides; Drug Resistance, Multiple, Bacterial; Humans; Membrane Transport Proteins; Microbial Sensitivity Tests; Pseudomonas aeruginosa

The aim was to assess the potency of the efflux pump inhibitors (EPIs) phenylalanine-arginine ß-naphthylamide (PAßN) and 1-(1-naphthylmethyl)-piperazine (NMP) and the putative natural EPI phenolic (-)-epigallocatechin gallate (EGCG) for the reversal of erythromycin, ciprofloxacin, and tetracycline resistance in Campylobacter jejuni and Campylobacter coli isolates. We investigated target mutations and resistant genes involved in erythromycin and tetracycline resistance and determined the roles of the bacterial drug efflux systems (cmeB, cmeF, and cmeR) in antimicrobial resistance. Our data show that most of the high-level erythromycin resistance and all of the tetracycline resistance can be explained through mutations in 23S rRNA and the presence of the tetO gene, respectively. The EPIs show the ability to partly reverse drug resistance in these Campylobacter isolates. Based on a fourfold or greater reduction in the erythromycin minimal inhibitory concentration (MIC), PAßN and NMP had clear effects in almost of all of the isolates tested. PAßN had a highly selective action on the ciprofloxacin and tetracycline MICs. Inactivation of cmeB increased susceptibility to all of the antimicrobials tested, whereas inactivation of cmeF and cmeR had no effects. A notable decrease in resistance to erythromycin and ciprofloxacin in the presence of subinhibitory concentrations of EGCG demonstrates the resistance-modifying activities of this natural EPI, and indicates its potential use in the control of Campylobacter spp. in the food chain.

Topics: Animals; Anti-Bacterial Agents; Campylobacter coli; Campylobacter jejuni; Catechin; Ciprofloxacin; Dipeptides; Drug Resistance, Multiple, Bacterial; Erythromycin; Humans; Membrane Transport Proteins; Microbial Sensitivity Tests; Piperazines; Tetracycline Resistance