Ziyu Song, Bingqian Du, Min Yuan, Jirao Shen, Shuai Xu, Wanchun Guan, Binghuai Lu, Zhenjun Li
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引用次数: 0
Abstract
Background: Antimicrobial resistance is prevalent across Nocardia species, with varying resistance profiles among different species, which poses significant challenges to effective treatment strategies. Our study aimed to assess the antimicrobial susceptibility profiles of various Nocardia species and investigate the potential correlation between resistance phenotypes and their underlying genotypes.
Methods: This study analyzed 148 clinical Nocardia isolates from 13 provinces in China. Minimum inhibitory concentrations (MICs) for 15 antimicrobial agents were determined using the microbroth dilution method. Whole genome sequencing (WGS) was performed for all isolates, followed by bioinformatics analyses integrated with 70 human-sourced Nocardia genomes in the National Center for Biotechnology Information (NCBI), encompassing species verification, phylogenetic analysis, and the identification of antimicrobial resistance genes (ARGs).
Results: Average Nucleotide Identity (ANI) analysis reclassified several misidentified isolates and revealed 14 potentially novel Nocardia species, underscoring the taxonomic complexity within this genus. Nocardia species exhibited distinct resistance profiles: Nocardia farcinica demonstrated elevated resistance to cephalosporins and tobramycin; Nocardia otitidiscaviarum showed broad resistance to β-lactams and quinolones; and Nocardia cyriacigeorgica exhibited resistance to quinolones, cefepime, and cefoxitin. Notably, clarithromycin resistance was consistently high across all species. Moreover, 38.51% of Nocardia isolates are resistant to two or more commonly used antibiotics, which revealed widespread multidrug resistance (MDR). Strong genotype-phenotype correlations were observed, including sul1 in sulfamethoxazole/trimethoprim-resistant N. farcinica, blaAST-1 in β-lactam-resistant N. otitidiscaviarum, and tetA/B(58) across tetracycline-intermediate isolates. Additionally, resistance mechanisms beyond ARGs were observed, including species-specific presence of warA and aph(2''), and gyrA mutations largely correlating with ciprofloxacin resistance. Nonetheless, resistance in some strains lacking known resistance determinants indicates the presence of uncharacterized mechanisms.
Conclusions: These findings provide critical insights into the drug resistance patterns of Nocardia strains and antimicrobial resistance genes, highlighting the importance of ongoing genomic surveillance and personalized treatments.
期刊介绍：
Frontiers in Cellular and Infection Microbiology is a leading specialty journal, publishing rigorously peer-reviewed research across all pathogenic microorganisms and their interaction with their hosts. Chief Editor Yousef Abu Kwaik, University of Louisville is supported by an outstanding Editorial Board of international experts. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, clinicians and the public worldwide.
Frontiers in Cellular and Infection Microbiology includes research on bacteria, fungi, parasites, viruses, endosymbionts, prions and all microbial pathogens as well as the microbiota and its effect on health and disease in various hosts. The research approaches include molecular microbiology, cellular microbiology, gene regulation, proteomics, signal transduction, pathogenic evolution, genomics, structural biology, and virulence factors as well as model hosts. Areas of research to counteract infectious agents by the host include the host innate and adaptive immune responses as well as metabolic restrictions to various pathogenic microorganisms, vaccine design and development against various pathogenic microorganisms, and the mechanisms of antibiotic resistance and its countermeasures.
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