Foreword

In modern medicine, antibacterials have made a significant contribution to the treatment of bacterial infectious diseases, but infections caused by drug-resistant bacteria that are resistant to these drugs have become one of the most serious problems worldwide in the 21st century. A. Fleming, who discovered the antibiotic penicillin, one of the greatest discoveries in human history or, to put it mildly, in the 20th century, pointed out the problems caused by drug-resistant bacteria around 1945. Appropriate use of antibiotics is, to some extent, effective in preventing the emergence and spread of drug-resistant bacteria. However, to fundamentally control antibacterial resistance, it is necessary to develop preventive or therapeutic methods. Therefore, it is important to understand the bacteriological characteristics of drug-resistant bacteria, including bacterial drug resistance mechanisms.

This special issue consists of four reviews and one regular article on antibacterial resistance, all of which were written by some of renowned Japanese pharmaceutical scientists on antibacterial resistance mechanisms. Dr. H. Nakaminami presents molecular epidemiological features of methicillin-resistant Staphylococcus aureus (MRSA) in Japan, and Dr. T. Wajima et al. present unique and ingenious mechanisms underlying antimicrobial resistance and spread of Haemophilus influenzae. I would like to apologize to Dr. Nakaminami and Dr. Wajima here in the Foreword. The review articles were completed in the fall of 2023. However, due to my own shortcomings, the publication was delayed until the spring of 2025. Dr. G. Kamoshida et al. present colistin resistance in Acinetobacter baumannii: basic and clinical insights. I would like to thank Dr. Kamoshida here in the Foreword that he also completed his article in the late of 2023 and updated it due to delay of publication in 2024. Dr. D. Morita and Dr. T. Kuroda present recent antimicrobial resistance surveillance and mechanisms of resistance to key antimicrobials in enterotoxigenic Escherichia coli. We would like to thank Dr. Kuroda for his kind response despite our very late invitation. Dr. K. Nishino and colleagues, of whom Dr. S. Yamasaki is the first author, present a regular article that a final point mutation analysis of the drug efflux pump MexB in clinical isolates of Pseudomonas aeruginosa. I am happy to get an opportunity to edit it, written by one of the best scientists in a similar field to me, that is, study on multidrug efflux pumps in Gram-negative bacteria.

It is unfortunate that, nowadays, basic research on drug-resistant bacteria is far less active compared to decades ago when I was a graduate student. I hope that basic research on antibacterial resistance will be re-emerged centered on the pharmaceutical researchers invited in the Current Topics to develop preventive or therapeutic strategies to control antibacterial-resistant bacterial infections.