Recent trend and research issues related to antimicrobial-resistant bacteria

The discovery of penicillin in 1928 was followed by the discovery and synthesis of various kinds of antimicrobial agents such as quinolone, aminogycoside, macrolide, tetracyclone, and oxazolidinone. These discoveries dramatically decreased the mortality rate due to infectious diseases. However, bacteria have also acquired antimicrobial-resistance genes or changed their own genes to oppose these antimicrobial agents, and now drug-resistant bacteria are becoming a serious clinical concern. Today, contagious diseases must be treated with the limited number of effective antimicrobial agents available. Infection control measures are required to prevent the spread of resistant bacteria in the clinical environment, and we must also increase our understanding of the drug-resistant mechanisms of bacteria. In this issue we wish to introduce the recent worldwide trend in antimicrobial-resistant bacteria, especially multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and multidrug-resistant Pseudomonas aeruginosa, along with recently-discovered antimicrobial-resistant systems.