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The aim of the study was to investigate the antibacterial and antibiofilm activities of Lavandula mairei and Thymus leptobotrys essential oils against Extended spectrum β-lactamase producing Enterobacteriaceae, responsible of nosocomial infections. PCR and sequencing methods detected three different resistance genes (blaSHV-42, blaSHV-12 et blaCTXM-15) in the studied strains. Gas chromatography-mass spectrometry analysis highlighted the predominance of carvacrol in both Lavandula mairei and Thymus leptobotrys essential oils. Their antibacterial activity was conducted by disk diffusion and microdilution methods. Great sensitivity of the multidrug resistant strains was noted for the two essential oils with inhibition zones' diameters ranging from 13.3±2.3 to 32.3±1.4 mm (Thymus leptobotrys) and from 22 to 34.66±0.57 mm (Lavandula mairei), and low minimal and bactericidal concentrations varying from 1.56 to 6.25 mg/mL (CMI) and from 1.56 to 12.5 mg/mL (CMB) for both essential oils. Four strains out of six, considered as the strongest biofilm producers by congo red agar and crystal violet methods, were chosen to evaluate biofilm inhibition and eradication effects of Lavandula mairei and Thymus leptobotrys essential oils. In most cases, these latter inhibited considerably the biofilm formation of the targeted strains with proportions greater than 80%. The eradication effect was lower, with rates not higher than 50%. Thus, these essential oils could be used as an effective alternative approach to prevent biofilm formation of multidrug resistant Enterobacteriaceae. To our knowledge, no previous works have reported the antibiofilm activity of Lavandula mairei and Thymus leptobotrys essential oils against these multidrug resistant bacteria. [ABSTRACT FROM AUTHOR]

Background and Aim: Acinetobacter baumannii is one of the most nosocomial pathogens as it can form biofilm on hospital surfaces. The objective of this work was to analyze the production of exopolysaccharides, extracellular proteins, and biofilm formation of carbapenem-resistant A. baumannii on silicone and ceramic surfaces. Materials and Methods: Qualitative and quantitative tests were conducted to evaluate the production of exopolysaccharides in different culture conditions. The Biuret method was applied for protein determination. Furthermore, the count of viable cultivable cells was used to study biofilm formation. For physicochemical characterization, the surfaces were subjected to contact angle measurements. Results: Incubation at 37°C with glucose (1.5%) was the optimal condition for producing exopolysaccharides. Glucose supplementation has also impacted the protein production by A. baumannii. Moreover, proteins were abundant in the extracellular matrix compared to exopolysaccharides (0.46 mg/mL for exopolysaccharides and 2.48 mg/mL for proteins). The strains formed biofilms on both surfaces but with different capacities, possibly due to the hydrophilic nature of ceramic and the hydrophobic nature of silicone. The addition of 1.5% glucose enhanced biofilm formation on ceramic for all strains. A positive correlation was established between the EPS concentration and the number of cells forming biofilm on silicone with 0.2% of glucose and between protein production and biofilm formed on ceramic with 0.2% and 1.5% of glucose. On the contrary, a negative correlation was detected between protein production and biofilm formation on the silicone surface with 0.2% glucose concentration. Conclusion: The environmental conditions significantly affect A. baumannii biofilm and its extracellular matrix compounds. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii (A. baumannii) is a Gram-negative opportunistic and nosocomial pathogen that is associated with most of the hospital epidemics. Its success can be directly attributed to its ability to survive under stressful hospital conditions (desiccation, nutrient starvation, and antimicrobial treatments). This survival ability results from the capacity of A. baumannii to form biofilms on the abiotic (polystyrene and glass) and biotic surfaces (epithelial cells and fungal filaments). The purpose of this review is to report different factors implicated in the biofilm formation of A. baumannii, notably biofilm-associated protein, CsuA/BABCD chaperone-usher pili system, poly-ß-1,6-N-acetylglucosamine, outer membrane protein A, quorum sensing, surface properties, and growing conditions. This review will also discuss the relationship between biofilm formation and multidrug resistance, in addition to several strategies that can be useful in the prevention and treatment of A. baumannii biofilm. [ABSTRACT FROM AUTHOR]