Sebastian Peter J, Schlesener Cory, Byrne Barbara A, Miller Melissa, Smith Woutrina, Batac Francesca, Goertz Caroline E C, Weimer Bart C, Johnson Christine K
EpiCenter for Disease Dynamics, One Health Institute, School of Veterinary Medicine, University of California, Davis, Davis, California, USA.
Karen C. Drayer Wildlife Health Center, One Health Institute, School of Veterinary Medicine, University of California, Davis, Davis, California, USA.
Appl Environ Microbiol. 2025 Mar 19;91(3):e0180824. doi: 10.1128/aem.01808-24. Epub 2025 Feb 3.
Antimicrobial resistance in species poses risks to both human and marine mammal health. Whole genome sequencing of spp. can be utilized to screen for antimicrobial resistance genes and allelic variants to provide mechanistic insights in ways that PCR screening and phenotypic interpretation cannot. Our goals were to (i) characterize antimicrobial resistance patterns of spp. pathogens isolated from southern sea otters (), northern sea otters (), and environmental samples from the central California coast using whole genome sequencing, and (ii) compare the presence of antimicrobial resistance genes with phenotypic interpretation from antibiotic susceptibility testing. Unexpectedly, genomic classification identified an understudied species, , in sea otter and environmental isolates that were previously identified as . A total of 489 spp. isolates were sequenced, and frequently detected antimicrobial resistance genes included multidrug efflux pumps and genes associated with resistance to ß-lactams and tetracyclines. Genes associated with resistance to fluoroquinolones, aminoglycosides, chloramphenicol, and sulfonamides were uncommon. Sea otter isolates were phenotypically susceptible to tetracycline despite carrying genes and . Both between- and within-species variations in ampicillin resistance were observed despite the ubiquitous presence of genes in , , and . Discordance between phenotypic and genotypic ampicillin resistance was especially noted for and was partially attributed to the allelic variation of the genes. Tetracyclines and fluoroquinolones, but not ß-lactams, are likely to be effective treatments for vibriosis in sea otters.
Vibriosis (infection with non-cholera spp.) is the most common seafood-borne illness globally, with major impacts on public health, food security, and wildlife health. Potential treatments of antimicrobial-resistant spp. in humans, aquaculture, and marine wildlife rehabilitation are complicated by current diagnostic challenges regarding bacterial species identification and interpretation of antimicrobial resistance patterns. Unexpected detection of previously misidentified in sea otters suggests that a broader taxonomic group of infect sea otters than previously described. We also determined that the presence of ß-lactamase genes alone in sea otter isolates does not necessarily correlate with an ampicillin-resistant phenotype, likely due to deleterious amino acid substitutions in certain alleles. Continued monitoring of spp. phenotypes and genotypes in sea otters is warranted to observe biologically relevant changes in antimicrobial resistance.
该物种的抗菌耐药性对人类和海洋哺乳动物的健康都构成风险。对该物种进行全基因组测序可用于筛选抗菌耐药基因和等位基因变体，从而以聚合酶链反应（PCR）筛选和表型解释无法做到的方式提供机制性见解。我们的目标是：（i）使用全基因组测序来表征从南海獭、北海獭以及加利福尼亚州中部海岸的环境样本中分离出的该物种病原体的抗菌耐药模式，以及（ii）将抗菌耐药基因的存在情况与抗生素敏感性测试的表型解释进行比较。出乎意料的是，基因组分类在海獭和环境分离株中鉴定出了一个此前研究较少的物种，该物种之前被鉴定为另一物种。总共对489株该物种的分离株进行了测序，经常检测到的抗菌耐药基因包括多药外排泵以及与对β-内酰胺类和四环素类耐药相关的基因。与对氟喹诺酮类、氨基糖苷类、氯霉素和磺胺类耐药相关的基因并不常见。尽管海獭分离株携带了某些基因，但在表型上对四环素敏感。尽管在该物种的多个菌株中普遍存在特定基因，但在氨苄西林耐药性方面观察到了种间和种内差异。尤其在某一物种中特别注意到了表型和基因型氨苄西林耐药性之间的不一致，部分原因是该基因的等位基因变异。四环素类和氟喹诺酮类药物，而非β-内酰胺类药物，可能是治疗海獭弧菌病的有效药物。
弧菌病（由非霍乱弧菌属感染引起）是全球最常见的食源性疾病，对公众健康、食品安全和野生动物健康有重大影响。目前在细菌物种鉴定和抗菌耐药模式解释方面的诊断挑战使人类、水产养殖和海洋野生动物康复中对抗菌耐药的弧菌属的潜在治疗变得复杂。在海獭中意外检测到之前被误鉴定的物种，这表明感染海獭的弧菌属分类群比之前描述的更广泛。我们还确定，海獭分离株中单独存在β-内酰胺酶基因并不一定与氨苄西林耐药表型相关，这可能是由于某些等位基因中存在有害的氨基酸取代。有必要持续监测海獭中弧菌属的表型和基因型，以观察抗菌耐药性方面具有生物学意义的变化。
