Journal of Microbiology

Reviews

Antibiotic hybrids: A promising strategy to replenish the pipeline and combat antimicrobial resistance: Yeongseo Lee, Yeo Jin Kim, Minhee Oh, Joon-Ho Lee, Saemee Song, Jaesung Kwak; Received October 13, 2025 Accepted December 24, 2025 Published online February 25, 2026; DOI: https://doi.org/10.71150/jm.2510006 [Epub ahead of print]

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Abstract PDF: Antimicrobial resistance (AMR) poses an ongoing threat to global health, with the number of deaths directly attributable to AMR projected to rise to 8 million. One of the main reasons for the current crisis is the depletion of antibiotic candidates in clinical pipelines. To address this, more preclinical candidates must be advanced into development. However, the scientific challenges and limited economic incentives associated with antibiotic research have further aggravated the situation. Antibiotic hybrids, which combine two antibiotics with different modes of action, have emerged as a promising strategy to overcome AMR and are already being developed for clinical use. This approach takes advantage of the strong selective pressure exerted when two bactericidal agents act simultaneously. Importantly, because hybrids are administered as a single chemical entity, they may offer advantages over conventional combination therapies, such as simplified pharmacokinetics and dosing. Furthermore, since clinically validated antibiotics are used as the building blocks of hybrids, this strategy provides an efficient platform for generating new lead compounds. Recently, the concept of antibiotic hybrids has expanded beyond antibiotic–antibiotic conjugates to include the attachment of functional molecules designed to mitigate the disadvantages of the parent antibiotics. In this review, we summarize the definition of antibiotic hybrids, highlight representative compounds that have entered clinical evaluation, and discuss recent advances in their development.

The rise and future of peptide-based antimicrobials: Hyo Jung Kim; Received October 9, 2025 Accepted November 5, 2025 Published online January 30, 2026; DOI: https://doi.org/10.71150/jm.2510002 [Epub ahead of print]

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Abstract PDF: The escalating threat of antimicrobial resistance has renewed global interest in peptide-based antibiotics as adaptable and effective alternatives to conventional small molecules. Peptides possess diverse mechanisms of action, high target specificity, and structural flexibility, which collectively limit the emergence of resistance. This review outlines recent advances spanning the discovery, optimization, and application of peptide antibiotics, from their biological origins and structural classifications to emerging strategies involving artificial intelligence, synthetic biology, and modern delivery technologies. Peptide antibiotics can be categorized by origin as natural, semi-synthetic, or fully synthetic, and further organized by structural class such as α-helical, β-sheet, cyclic, and extended forms. They are also grouped by function into membrane-targeted and non-membrane-targeted types. These classification schemes are not only descriptive but also critical for understanding the therapeutic potential of peptides, as each category presents distinct advantages and engineering challenges that influence stability, specificity, and overall clinical performance. Advances in artificial intelligence, synthetic biology, and continuous manufacturing are reshaping how peptide drugs are designed and produced, while innovations in drug delivery systems are addressing critical issues of stability and bioavailability. Together, these developments are laying the foundation for a new generation of peptide-based therapeutics capable of meeting the evolving challenges of antimicrobial resistance.

Full articles

Staphylococcus parequorum sp. nov. and Staphylococcus halotolerans sp. nov., isolated from traditional Korean soybean foods: Ju Hye Baek, Dong Min Han, Dae Gyu Choi, Chae Yeong Moon, Jae Kyeong Lee, Chul-Hong Kim, Jung-Woong Kim, Che Ok Jeon; J. Microbiol. 2025;63(8):e2503003. Published online August 31, 2025; DOI: https://doi.org/10.71150/jm.2503003; Correction in: J. Microbiol 2025;63(9):e2509100 Correction in: J. Microbiol 2025;63(10):e2510101

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Abstract PDF Supplementary Material

Strains Mo2-6^T, S9, KG4-3^T, and 50Mo3-2, identified as coagulase-negative, Gram-stain-positive, halotolerant, non-motile coccoid bacteria, were isolated from traditional Korean soybean foods. Strains Mo2-6^T and S9 were both catalase- and oxidase-negative, whereas KG4-3^T and 50Mo3-2 were catalase-positive but oxidase-negative. The optimal growth conditions for Mo2-6^T and S9 were 30°C, 2% NaCl, and pH 7.0, while KG4-3^T and 50Mo3-2 grew best at 35°C, 2% NaCl, and pH 7.0. All strains contained menaquinone-7 as the predominant isoprenoid quinone, with anteiso-C_15:0 and iso-C_15:0 as the major cellular fatty acids (> 10%). Additionally, anteiso-C_13:0 was a major fatty acid in strain KG4-3^T. The DNA G + C contents of strains Mo2-6^T, S9, KG4-3^T, and 50Mo3-2 were 33.4%, 33.3%, 32.5%, and 32.7%, respectively. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strains Mo2-6^T and S9, as well as KG4-3^T and 50Mo3-2, formed distinct lineages within the genus Staphylococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) analyses confirmed that strains Mo2-6^T and S9, as well as KG4-3^T and 50Mo3-2, belonged to the same species. Meanwhile, dDDH and ANI values between strains Mo2-6^T and KG4-3^T, as well as comparisons with other Staphylococcus type strains, were below the species delineation thresholds, indicating they represent novel species. Based on phenotypic, chemotaxonomic, and molecular data, we propose strain Mo2-6^T as the type strain of Staphylococcus parequorum sp. nov. (=KACC 23685^T =JCM 37038^T) and strain KG4-3^T as the type strain of Staphylococcus halotolerans sp. nov. (=KACC 23684^T =JCM 37037^T).

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Validation List no. 227: valid publication of new names and new combinations effectively published outside the IJSEM
Aharon Oren, Markus Göker
International Journal of Systematic and Evolutionary Microbiology .2026;[Epub] CrossRef

Whole-genome characterization and global phylogenetic comparison of cefotaxime-resistant Escherichia coli isolated from broiler chickens: Shahana Ahmed, Tridip Das, Chandan Nath, Tahia Ahmed, Keya Ghosh, Pangkaj Kumar Dhar, Ana Herrero-Fresno, Himel Barua, Paritosh Kumar Biswas, Md Zohorul Islam, John Elmerdahl Olsen; J. Microbiol. 2025;63(4):e2412009. Published online April 29, 2025; DOI: https://doi.org/10.71150/jm.2412009

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Abstract PDF Supplementary Material

Antimicrobial resistance (AMR) poses a serious threat to public health, with the emergence of extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae, particularly Escherichia coli, raising significant concerns. This study aims to elucidate the drivers of antimicrobial resistance, and the global spread of cefotaxime-resistant E. coli (CREC) strains. Whole-genome sequencing (WGS) was performed to explore genome-level characteristics, and phylogenetic analysis was conducted to compare twenty CREC strains from this study, which were isolated from broiler chicken farms in Bangladesh, with a global collection (n = 456) of CREC strains from multiple countries and hosts. The MIC analysis showed over 70% of strains isolated from broiler chickens exhibiting MIC values ≥ 256 mg/L for cefotaxime. Notably, 85% of the studied farms (17/20) tested positive for CREC by the end of the production cycle, with CREC counts increasing from 0.83 ± 1.75 log10 CFU/g feces on day 1 to 5.24 ± 0.72 log10 CFU/g feces by day 28. WGS revealed the presence of multiple resistance genes, including bla_CTX-M, which was found in 30% of the strains. Phylogenetic comparison showed that the Bangladeshi strains were closely related to strains from diverse geographical regions and host species. This study provides a comprehensive understanding of the molecular epidemiology of CREC. The close phylogenetic relationships between Bangladeshi and global strains demonstrate the widespread presence of cefotaxime-resistant bacteria and emphasize the importance of monitoring AMR in food-producing animals to mitigate the spread of resistant strains.

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ESBL-Producing E. coli in Captive Black Bears: Molecular Characteristics and Risk of Dissemination
Xin Lei, Mengjie Che, Yuxin Zhou, Shulei Pan, Xue Yang, Siyu Liu, Iram Laghari, Mingyue Wu, Ruilin Han, Xiaoqi Li, Lei Zhou, Guangneng Peng, Haifeng Liu, Ziyao Zhou, Kun Zhang, Zhijun Zhong
Veterinary Sciences.2025; 12(11): 1085. CrossRef
Resistome patterns in poultry farms: from genes to ecosystems
Olga S. Chemisova, Darya A. Sedova, Alina A. Sereda, Yuliya P. Gordeeva
Ecological genetics.2025; 23(4): 375. CrossRef

Review

Small regulatory RNAs as key modulators of antibiotic resistance in pathogenic bacteria: Yubin Yang, Hana Hyeon, Minju Joo, Kangseok Lee, Eunkyoung Shin; J. Microbiol. 2025;63(4):e2501027. Published online April 2, 2025; DOI: https://doi.org/10.71150/jm.2501027

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