Genetics of antimicrobial resistance.
ABSTRACT Antimicrobial resistant strains of bacteria are an increasing threat to animal and human health. Resistance mechanisms to circumvent the toxic action of antimicrobials have been identified and described for all known antimicrobials currently available for clinical use in human and veterinary medicine. Acquired bacterial antibiotic resistance can result from the mutation of normal cellular genes, the acquisition of foreign resistance genes, or a combination of these two mechanisms. The most common resistance mechanisms employed by bacteria include enzymatic degradation or alteration of the antimicrobial, mutation in the antimicrobial target site, decreased cell wall permeability to antimicrobials, and active efflux of the antimicrobial across the cell membrane. The spread of mobile genetic elements such as plasmids, transposons, and integrons has greatly contributed to the rapid dissemination of antimicrobial resistance among several bacterial genera of human and veterinary importance. Antimicrobial resistance genes have been shown to accumulate on mobile elements, leading to a situation where multidrug resistance phenotypes can be transferred to a susceptible recipient via a single genetic event. The increasing prevalence of antimicrobial resistant bacterial pathogens has severe implications for the future treatment and prevention of infectious diseases in both animals and humans. The versatility with which bacteria adapt to their environment and exchange DNA between different genera highlights the need to implement effective antimicrobial stewardship and infection control programs in both human and veterinary medicine.
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ABSTRACT: Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for several difficult-to-treat infections in humans. MRSA is any strain of Staphylococcus aureus that has developed, through the process of natural selection, resistance to betalactam antibiotics .The appearance of (MRSA) strains has created serious therapeutical problems. In this article, we present an overview of the biochemical and genetic mechanisms of pathogenicity of S. aureus strains. Virulence factors, organization of the genome and regulation of expression of genes involved in virulence, and mechanisms leading to methicilin resistance are presented. This review describe the management of severe healthcare-associated infections due to methicillin-resistant Staphylococcus aureus (MRSA), including the limitations of current therapy, potential alternative agents, new therapeutic options.06/2014;
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ABSTRACT: Abstract: The edible mushroom Agaricus blazei Murill is known to induce protective immunomodulatory action against a variety of infectious diseases. In the present study we report potential anti-quorum sensing properties of A. blazei hot water extract. Quorum sensing (QS) plays an important role in virulence, biofilm formation and survival of many pathogenic bacteria, including the Gram negative Pseudomonas aeruginosa, and is considered as a novel and promising target for anti-infectious agents. In this study, the effect of the sub-MICs of Agaricus blazei water extract on QS regulated virulence factors and biofilm formation was evaluated against P. aeruginosa PAO1. Sub-MIC concentrations of the extract which did not kill P. aeruginosa nor inhibited its growth, demonstrated a statistically significant reduction of virulence factors of P. aeruginosa, such as pyocyanin production, twitching and swimming motility. The biofilm forming capability of P. aeruginosa was also reduced in a concentration-dependent manner at sub-MIC values. Water extract of A. blazei is a promising source of antiquorum sensing and antibacterial compounds. Keywords: Agaricus blazei; mushroom; antiqourum sensing activity; antimicrobial activity; antibiofilm activity; Pseudomonas aeruginosaMolecules. 04/2014; 19:4189-4199.