oa Editorial [Hot Topic Progress in Fighting the Multidrug Resistance of Bacteria to Treatment (Guest Editor: Mihail-Lucian Pascu)]

Multidrug resistant (MDR) bacteria constitute an ever-increasing threat to public health. The main mechanism of MDR is the active expulsion of drugs by bacterial pumps that expel unrelated compounds. The increase of knowledge, the understanding of efflux-mediated resistance and the translation of it into the development of original antimicrobials constitute important areas to report new results. The prevalence and the evolution of bacterial drug efflux mechanisms and its genetic regulation, the identification of the risk factors, and the synthesis and evaluation of molecules that obviate efflux-mediated resistance are subjects of interest at the moment, which may convincingly justify a special issue of Letters in Drug Design Discovery. Papers on molecular basis of drug efflux, structural genomics, molecular modelling, production of new molecules and their time stability, chemosensitizers or inhibitory agents are included in this issue. This is part of a multi- and inter-disciplinary approach to identify new targets and provide a generation of effective agents against efflux mechanisms in MDR bacterial pathogens. More general, infectious diseases cause more than 13 millions deaths each year. This high mortality impact will possibly increase, due to accelerated evolution of antibiotic resistance in important human pathogens and the scarcity of new anti-infective drug families. On the other hand, the development of antibiotic resistance is a natural evolutionary process which induces erosions of the effectiveness of the arsenal of antibiotics, leading to increased mortality in humans and even fauna. This is also related to global warming and the extreme conditions of natural and artificial origins in which humans are obliged to live and work nowadays. A significant number of papers, institutions and countries contribute to this issue; the articles are mainly review articles, but some of them are devoted to new results and the related methods obtained/ developed by the respective authors, who belong to prestigious research centres active in MDR studies. In total, 30 authors from 12 research institutions/universities located in 6 countries contribute to this special issue; most of them are participants at the European COST network named ATENS which includes among its members groups of outstanding scientists working to integrate in Europe the research efforts dedicated to fight against MDR . I hope this special volume of LDDD will provide the reader with an understanding of MDR research, its progress, and results obtained by some of the best scientific European communities dedicated to this subject.