MexXY Multidrug Efflux System Is More Frequently Overexpressed in Ciprofloxacin Resistant French Clinical Isolates Compared to Hospital Environment Ones.

Modulation of the membrane permeability through a decrease in porin-mediated antibiotic entry and/or an increase in antibiotic efflux is one of the resistance mechanisms to antibiotics evolved by Gram-negative bacteria. To assess whether the outer membrane porin OprD and Resistance-Nodulation-Division (RND) efflux pumps were similarly expressed in 33 ciprofloxacin-resistant clinical strains of Pseudomonas aeruginosa and in 30 non-clinical strains originating from the hospital environment (mainly waterborne Pseudomonas aeruginosa), the expression of oprD, mexB, mexF, and mexY genes was investigated. Overall, the expression of oprD was not detected by RT-qPCR in 14 (22%) strains and underexpressed in 35 (56%) more. No significant difference in oprD expression was detected between clinical and non-clinical strains. As for efflux pumps, 23 (70%) of the clinical strains overexpressed at least one of the tested RND genes. Overexpression of mexB, mexF and mexY was detected in 27, 12, and 45% of the clinical strains, respectively. In the 30 non-clinical strains, no overexpression could be found for mexB, mexF, or mexY. On the contrary, a global underexpression of the tested efflux pump genes was recorded. In both clinical and environmental strains, a positive correlation was found between the expressions of oprD and mexB. Similarly, the expressions of oprD and mexF were positively correlated. This result contrasts with the inverse correlation between both MexAB-OprM/MexEF-OprN and OprD previously described in carbapenem-resistant P. aeruginosa strains. The only positive correlation between phenotypic ciprofloxacin minimum inhibitory concentrations (MICs) and the expression of efflux pump gene was witnessed with mexY (analysis on pooled results for clinical and environmental strains). However, in clinical strains, no statistically significant link could be found between the degree of reduction in ciprofloxacin MICs witnessed with Phenylalanine-Arginine ß-naphthylamide (PAßN) and the expression of any of the 3 RND genes tested.

In vitro study on the activity of essential oil and methanolic extract from Algerian Nigella sativa L. Seeds on the growth kinetics of micro-organisms isolated from the buccal cavities of periodontal patients.

An in vitro evaluation of the antimicrobial activity of essential oil (EO) and methanol extract (ME) from Algerian Nigella sativa L. seeds against microbial strains isolated from the oral cavities of periodontal patients was performed. Twelve Gram-positive bacteria, eleven Gram-negative bacteria and three microscopic fungi strains were isolated and identified. The antimicrobial activities of EO and ME were tested against Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, Klebsiella pneumoniae, Proteus sp., Acinetobacter baumannii/calcoaceticus, Porphyromonas sp., Veillonella sp., Candida sp. and Saccharomyces sp.. The total polyphenol and flavonoids contents of ME were higher than those of EO. Thin layer chromatography showed that catechin, gallic acid and quercetin were most likely present in the extracts. Fourier transform infrared spectrometry analysis (FT-IR) indicated the presence of bands from the CO groups of acids, alcohols, phenols, and ethers and the C[bond, double bond]O band of aldehydes. Analysis of the antimicrobial activity of N. sativa extracts obtained by the microdilution method showed excellent bactericidal activity of the essential oil and moderate efficiency of the ME against all the microbes tested. Staphylococcus epidermidis and Porphyromonas sp. were the most sensitive to EO (minimum bactericidal concentration (MBC): 16,500 µg/ml) at 48 h of incubation and, 125,000 µg/ml of ME was the most active against all the microbes tested. However, after18 or 24 h, this efficiency was decreased in some strains. In addition, Saccharomyces sp. and Candida albicans were more sensitive to EO than ME during the incubation, while this efficiency was clearly not visible with the agar well method, and most microbes tested presented remarkable resistance to these extracts.

In vitro and in vivo antimicrobial activity of Algerian Hoggar Salvadora persica L. extracts against microbial strains from children's oral cavity.

ETHNOPHARMACOLOGICAL RELEVANCE: Salvadora persica L. (miswak) is traditionally used to ensure oral hygiene Muslim people in developing countries where it is growing. The antibacterial properties of Salvadora persica L. originating from various geographic areas have already been reported. However, they have never been tested for samples originating from Hoggar, where extreme weather conditions could lead to different properties for this Salvadora persica L. ecotype. AIM OF THE STUDY: To assess the in vitro and in vivo antimicrobial activities of methanolic extract of Algerian Hoggar Salvadora persica L. (miswak) on some isolated and identified strains from the oral cavity of school children aged from 6 to 12 with (n=20) and without (n=20) caries. MATERIALS AND METHODS: After a qualitative and quantitative analysis of dental plaque samples from the selected children, the effect of methanolic extract of Hoggar miswak against oral bacterial and fungal strains isolated from the oral cavity of children with caries was tested by both agar disc diffusion and microdilution methods. The stability and physicochemical parameters of Hoggar Salvadora persica L. mouthwash were also assessed compared. The in vivo antimicrobial effect of Hoggar miswak rinse on dental plaque samples was also tested over a week. RESULTS: Four bacterial genera (Staphylococcus, Streptococcus, Escherichia and Lactobacillus) were commonly identified in all subjects at different colonization levels. A statistically significant difference in colonization levels between the two groups of children was recorded. Hoggar miswak extract more significantly inhibited the growth of Gram negative bacteria from the dental plaque than Gram positive ones. Hoggar Salvadora persica L. mouthwash was stable at 4 °C and 25 °C over the period of conservation (one week) while a temperature of 40 °C induced variations in the physicochemical parameters and considered not suitable for preservation. The in vivo study revealed a significant reduction in bacteria of the oral cavity using miswak mouthwash as compared to placebo. CONCLUSION: Hoggar miswak extract displayed a strong antimicrobial effect both in vitro and in vivo. Its use as a mouthrinse could therefore be recommended as a preventive measure to preserve from tooth decay.