Evaluation of three plant extracts against biofilm formation and expression of quorum sensing regulated virulence factors in Pseudomonas aeruginosa

Following the increasing antibiotic resistance of pathogenic bacteria, the use of medicinal herbs as antibacterial agents has attracted growing attention. Pseudomonas aeruginosa is a human opportunistic pathogen that uses quorum sensing for regulating virulence gene expression [pyocyanin, protease, and elastase production and biofilm formation]. This study examined the anti-quorum sensing activity of Quercus infectoria, Zataria multiflora and Trachyspermum copticum extracts on standard P. aeruginosa strain. The minimum inhibitory concentration [MIC] of Q. infectoria, Z. multiflora and T. copticum extracts for standard P. aeruginosa strain was determined through micro dilution. Microtiter plates were used to evaluate the anti-quorum sensing effects of the three extracts [at a sub-MIC concentration] on pyocyanin, protease, and elastase production and biofilm formation. The acetone extract of Q. infectoria showed the highest anti-quorum sensing activity and reduced the pyocyanin, protease, and elastase production and biofilm formation by 89.1%, 78%, 73.3%, and 70.1%, respectively. The corresponding values were 88.2%, 72.1%, 69%, and 61.1% for the methanol extract of Z. multiflora and 70.6%, 63.42%, 60.1%, and 59.1% for the methanol extract of T. copticum. Considering the high anti-quorum sensing activity of the studied extracts, especially the acetone extract of Q. infectoria, these herbs can be used as antipathogenic drugs

Antibacterial activity of propolis ethanol extract against antibiotic resistance bacteria isolated from burn wound infections

Burn wound is a suitable site for incidence of resistant infections; thus, the research for finding effective drugs against this infection is necessary. The purpose of this study was to determine antibacterial activity of Isfahan bee propolis extracts against beta-lactamase producing bacteria isolated from burn wound infections. Ethanol extract of Isfahan bee propolis was prepared by 28 g of propolis in 100 ml of 70% ethanol. Antibacterial activity of ethanol extracts were evaluated against beta-lactamase producing bacteria [Staphylococcus aureus and Pseudomonas aeruginosa] isolated of burn wound infection by well diffusion method. Broth serial dilution method was used to determine MBC of extract. Beta-lactamase production of isolates was detected by iodometric test, imipenem-EDTA combined disk test and imipenem-EDTA double-disk synergy test. Ethanol extract of propolis was found to be the most effective against S. aureus strains [inhibition zone=17.66 +/- 0.47 mm] than P. aeruginosa strains [inhibition zone=7 mm]. The MIC and MBC values of the extracts against S. aureus strains were 0.0143 and 0.0286 mg/ml and these values against P. aeruginosa strains were 0.75 and 1.5 mg/ml, respectively. Among the S. aureus clinical isolates, all of strains produced beta-lactamase. Imipenem-EDTA double-disk synergy test showed that only one clinical isolate of P. aeruginosa was metallo-beta-lactamase positive. This study demonstrated that ethanol extract of Isfahan bee propolis is mainly active against S. aureus and it is effective on P. aeruginosa at higher concentration. Ethanol extract of propolis did not inhibit production of beta-lactamase enzyme in tested bacteria

Evaluation of antibacterial activity of extract of rumex alveollatus leaf against staphylococcus aureus and pseudomonas aeruginosa

There is considerable interest in alternative approaches for eradication of infections causes by pathogenic bacteria especially resistant bacteria. Methanol and ethanol extracts of Rumex alveollatus leaves were evaluated for in vitro antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains. In this empirical-experimental study, the agar plate well diffusion method was used for antibacterial assay of different sample. Broth microdilution method was used for evaluate Minimum inhibitory concentration [MIC] and Minimal bactericidal concentration [MBC] of extracts. All extracts demonstrated significant inhibitory effect against selected bacterial strains. There were statistically significant correlations between antibacterial activity and concentration of the extracts [p<0.05]. The MIC values of the extracts ranged from 31.3 mg/ml to 62.5 mg/ml whereas the MBC values ranged from 62.5 mg/ml to 125.0 mg/ml. Result from these finding suggest that methanol and ethanol extracts of Rumex alveollatus leaves may be used as natural antibacterial for treatment of some diseases, especially local skin diseases