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International audience; This study reports the in vitro efficacy of a mixture of plant extracts used as antibacterial agents loaded in a dressing to prevent infection in a wound. These natural compounds were extracted from avocado and mango.A mixture of equal proportions of petroleum ether extract from avocado kernels and methanolic extract from mango kernels was effective on the majority of 36 bacterial strains and presented excellent results against S. aureus. The Minimal Inhibitory Concentrations (MIC) measured on Staphylococcus aureus (ATCC 6538) were 0.019 mg/mL for the mixture compared to 0.039 mg/mL for the avocado or mango extract alone. This mixture was incorporated into a wound dressing composed of non-woven fabric and a gel. This gel consists of a plasticizer (starch/glycerin) and an absorbent (CMC/PCD) and is designed to have swelling properties and entrap plant extract. A formulation containing equal proportions of CMC and PCD enabled us to obtain 800% of swelling and a good adhesion of the gel to the non-woven fabric.The final dressing containing the mixture of avocado and mango extracts presented excellent antibacterial activity against S. aureus. Microbiological tests demonstrated that a wound dressing loaded with avocado/mango seed extract induced additional bacterial reduction of 3 Log10 and 2 Log10 against S. aureus and P. aeruginosa respectively but no additional bacterial reduction of C. albicans compared to the control.Our study demonstrated the scope for interest in plant species extracts provided by agricultural co-products in developing a new antibacterial wound dressing.

New anti-infective agents are urgently needed to fight microbial resistance. Methicillin-resistant Staphylococcus aureus (MRSA) strains are particularly responsible for complicated pathologies that are difficult to treat due to their virulence and the formation of persistent biofilms forming a complex protecting shell. Parasitic infections caused by Trypanosoma brucei and Leishmania mexicana are also of global concern, because of the mortality due to the low number of safe and effective treatments. Female inflorescences of hop produce specialized metabolites known for their antimicrobial effects but underexploited to fight against drug-resistant microorganisms. In this study, we assessed the antimicrobial potential of phenolic compounds against MRSA clinical isolates, T. brucei and L. mexicana. By fractionation process, we purified the major prenylated chalcones and acylphloroglucinols, which were quantified by UHPLC-UV in different plant parts, showing their higher content in the active flowers extract. Their potent antibacterial action (MIC < 1 µg/mL for the most active compound) was demonstrated against MRSA strains, through kill curves, post-antibiotic effects, anti-biofilm assays and synergy studies with antibiotics. An antiparasitic activity was also shown for some purified compounds, particularly on T. brucei (IC50 < 1 to 11 µg/mL). Their cytotoxic activity was assessed both on cancer and non-cancer human cell lines.

Objective The main goal of this study was to determine the in vitro susceptibility of strains collected from marketed probiotics to antibiotics used to treat community-acquired infections. Methods The minimum inhibitory concentrations (MICs) of 16 antibiotics were determined using a gradient strip (E test) or the agar dilution method for fidaxomicin. Results The probiotics demonstrated various antibiotic patterns. Bacterial probiotics are generally susceptible to most prescribed antibiotics orally administered, whereas yeast probiotics, such as Saccharomyces boulardii , are resistant. Conclusion Special attention must be paid to co-prescriptions of antibiotics and probiotics to ensure that the probiotic strain is not susceptible.

International audience

NXL104 is a new β-lactamase inhibitor (BLI) that inhibits class A and class C β-lactamase enzymes. In this study, the activity of NXL104 in combination with the third-generation cephalosporins ceftazidime (CAZ) and ceftriaxone (CRO) or with piperacillin (PIP) was evaluated against 316 anaerobic bacteria. Minimum inhibitory concentrations (MICs) were determined using an agar dilution method. The BLIs NXL104 or tazobactam (TAZ) were added to the β-lactams at a fixed concentration of 4 mg/L. A triple combination of NXL104 with an 8:1 ratio of CAZ and metronidazole (MTZ) was also tested. The activities of CAZ, CRO and PIP in combination with NXL104 were enhanced against many of the bacteria. MIC(50) values (MIC for 50% of the organisms) for CAZ+NXL104 were 8-16-fold lower than those of CAZ against Gram-negative anaerobes. Antibiotic resistance rates against all anaerobic strains were: CAZ, 37.7%; CRO, 31%; CAZ+NXL104, 15.2%; CRO+NXL104, 5.4%; and MTZ, 4.1%. No resistant strains could be observed with PIP+TAZ, PIP+NXL104 or the triple combination MTZ+CAZ+NXL104. In conclusion, the triple combination of MTZ+CAZ+NXL104 demonstrated potent antibacterial activity against anaerobes representing most clinical species. It appears appropriate for the treatment of polymicrobial infections, since CAZ+NXL104 also exhibits potent activity against β-lactamase-producing Enterobacteriaceae and Pseudomonas aeruginosa. It is currently being tested in phase 2 clinical trials for the treatment of complicated intra-abdominal infections.

Primary biological examination of four extracts of the leaves and stems ofHyptis atrorubensPoit. (Lamiaceae), a plant species used as an antimicrobial agent in Guadeloupe, allowed us to select the hydromethanolic extract of the stems for further studies. It was tested against 46 microorganismsin vitro. It was active against 29 microorganisms. The best antibacterial activity was found against bacteria, mostly Gram-positive ones. Bioautography enabled the isolation and identification of four antibacterial compounds from this plant: rosmarinic acid, methyl rosmarinate, isoquercetin, and hyperoside. The MIC and MBC values of these compounds and their combinations were determined against eight pathogenic bacteria. The best inhibitory and bactericidal activity was found for methyl rosmarinate (0.3 mg/mL). Nevertheless, the bactericidal power of rosmarinic acid was much faster in the time kill study. Synergistic effects were found when combining the active compounds. Finally, the inhibitory effects of the compounds were evaluated on the bacterial growth phases at two different temperatures. Our study demonstrated for the first time antimicrobial activity ofHyptis atrorubenswith identification of the active compounds. It supports its traditional use in French West Indies. Although its active compounds need to be further evaluatedin vivo, this work emphasizes plants as potent sources of new antimicrobial agents when resistance to antibiotics increases dramatically.