Journal of Microbiology

EDITORIAL] Perspectives towards antibiotic resistance: from molecules to population: Joon-Hee Lee; J. Microbiol. 2019;57(3):181-184.; DOI: https://doi.org/10.1007/s12275-019-0718-8

Abstract: For a long time, antibiotics have been ‘magical weapons’ to combat pathogenic microbes. The success of antibiotics is now greatly threatened by resistance to antibiotics and many scientists have already talked about the coming of the postantibiotic era. This special issue is prepared to understand recent research findings and new concepts about antibiotic resistance. Above all, this special issue explores mechanisms for the generation, selection, and spread of antibiotic resistance, and gives insight into what to target to prevent the development of antibiotic resistance. Just as antibiotics came from the concept of “magic bullet”, a breakthrough will come from a new concept based on a profound understanding of antibiotic resistance.

REVIEW] Recent paradigm shift in the assembly of bacterial tripartite efflux pumps and the type I secretion system: Inseong Jo , Jin-Sik Kim , Yongbin Xu , Jaekyung Hyun , Kangseok Lee , Nam-Chul Ha; J. Microbiol. 2019;57(3):185-194. Published online February 26, 2019; DOI: https://doi.org/10.1007/s12275-019-8520-1

Abstract: Tripartite efflux pumps and the type I secretion system of Gram-negative bacteria are large protein complexes that span the entire cell envelope. These complexes expel antibiotics and other toxic substances or transport protein toxins from bacterial cells. Elucidating the binary and ternary complex structures at an atomic resolution are crucial to understanding the assembly and working mechanism. Recent advances in cryoelectron microscopy along with the construction of chimeric proteins drastically shifted the assembly models. In this review, we describe the current assembly models from a historical perspective and emphasize the common assembly mechanism for the assembly of diverse tripartite pumps and type I secretion systems.

REVIEW] Antibiotic-resistant clones in Gram-negative pathogens: presence of global clones in Korea: Kwan Soo Ko; J. Microbiol. 2019;57(3):195-202. Published online October 2, 2018; DOI: https://doi.org/10.1007/s12275-019-8491-2

Abstract: Antibiotic resistance is a global concern in public health. Antibiotic-resistant clones can spread nationally, internationally, and globally. This review considers representative antibiotic-resistant Gram-negative bacterial clones–CTX-M- 15-producing ST131 in Escherichia coli, extended-spectrum β-lactamase-producing ST11 and KPC-producing ST258 in Klebsiella pneumoniae, IMP-6-producing, carbapenem-resistant ST235 in Pseudomonas aeruginosa, and OXA-23- producing global clone 2 in Acinetobacter baumannii–that have disseminated worldwide, including in Korea. The findings highlight the urgency for systematic monitoring and international cooperation to suppress the emergence and propagation of antibiotic resistance.

REVIEW] Antibacterial strategies inspired by the oxidative stress and response networks: So Youn Kim , Chanseop Park , Hye-Jeong Jang , Bi-o Kim , Hee-Won Bae , In-Young Chung , Eun Sook Kim , You-Hee Cho; J. Microbiol. 2019;57(3):203-212. Published online February 26, 2019; DOI: https://doi.org/10.1007/s12275-019-8711-9

Abstract: Oxidative stress arises from an imbalance between the excessive accumulation of reactive oxygen species (ROS) and a cell’s capability to readily detoxify them. Although ROS are spontaneously generated during the normal oxygen respiration and metabolism, the ROS generation is usually augmented by redox-cycling agents, membrane disrupters, and bactericidal antibiotics, which contributes their antimicrobial bioactivity. It is noted that all the bacteria deploy an arsenal of inducible antioxidant defense systems to cope with the devastating effect exerted by the oxidative stress: these systems include the antioxidant effectors such as catalases and the master regulators such as OxyR. The oxidative stress response is not essential for normal growth, but critical to survive the oxidative stress conditions that the bacterial pathogens may encounter due to the host immune response and/or the antibiotic treatment. Based on these, we here define the ROS-inspired antibacterial strategies to enhance the oxidative stress of ROS generation and/or to compromise the bacterial response of ROS detoxification, by delineating the ROSgenerating antimicrobials and the core concept of the bacterial response against the oxidative stress.

REVIEW] Ribosome dependence of persister cell formation and resuscitation: Thomas K. Wood , Sooyeon Song , Ryota Yamasaki; J. Microbiol. 2019;57(3):213-219. Published online February 26, 2019; DOI: https://doi.org/10.1007/s12275-019-8629-2

Abstract: Since most bacterial cells are starving, they must enter a resting stage. Persister is the term used for metabolically-dormant cells that are not spores, and these cells arise from stress such as that from antibiotics as well as that from starvation. Because of their lack of metabolism, persister cells survive exposure to multiple stresses without undergoing genetic change; i.e., they have no inherited phenotype and behave as wild-type cells once the stress is removed and nutrients are presented. In contrast, mutations allow resistant bacteria to grow in the presence of antibiotics and slow growth allows tolerant cells to withstand higher concentrations of antibiotics; hence, there are three closely-related phenotypes: persistent, resistant, and tolerant. In addition, since dormancy is so prevalent, persister cells must have a means for resuscitating (since so many cells should obtain this resting state). In this review, we focus on what is known about the formation and resuscitation of persister cells.

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