Department of Bacterial and Parasitic Diseases, Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand.
Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
PLoS One. 2021 Feb 5;16(2):e0246598. doi: 10.1371/journal.pone.0246598. eCollection 2021.
Arcobacter butzleri is an emerging zoonotic food-borne and water-borne pathogen that can cause diarrhea in humans. The global prevalence of A. butzleri infection is underestimated, and little is known about their phenotypic and genotypic characterization. The aim of this study was to determine antimicrobial susceptibility (AST) profiles, detect related virulence genes, and classify sequence type (ST) of A. butzleri isolates obtained from human stool and food samples. A total of 84 A. butzleri isolates were obtained from human diarrheal (n = 25), non-diarrheal (n = 24) stool, and food (n = 35) samples in Thailand. They were evaluated for phenotypic identification by conventional microbiological procedures and AST by Kirby-Bauer disc diffusion method as well as virulence genes detection. Representative isolates from each origin were selected based on the presence of virulence genes and AST profiles to analyze genetic diversity by multilocus sequence typing (MLST). All isolates showed resistance to nalidixic acid 40.5% (34/84), ciprofloxacin 11.9% (10/84), azithromycin 8.3% (7/84), and erythromycin 3.6% (3/84). Regarding the ten virulence genes detected, cj1349, mviN and pldA had the highest prevalence 100% (84/84), followed by tlyA 98.8% (83/84), cadF 97.6% (82/84), ciaB 71.4% (60/84), hecA and hecB 22.6% (19/84), iroE 15.5% (13/84) and irgA 10.7% (9/84), respectively. Three virulence genes were present among A. butzleri isolates of human diarrheal stool and food samples, with a significant difference observed among isolates; hecB [36% (9/25) and 8.6% (3/35)], hecA [36% (9/25) and 5.7% (2/35)], and irgA [24% (6/25) and 2.9% (1/35)] (p < 0.05), respectively. The hecA and hecB virulence genes functions are related to the mechanism of hemolysis, while irgA supports a bacterial nutritional requirement. MLST analysis of 26 A. butzleri isolates revealed that 16 novel STs exhibited high genetic diversity. The results of this study is useful for understanding potentially pathogenic and antimicrobial-resistant A. butzleri in Thailand. The pathogenic virulence markers hecB, hecA, and irgA have the potential to be developed for rapid diagnostic detection in human diarrheal stool. No significant relationships among STs and sources of origin were observed. Little is known about A. butzleri, the mechanism of action of these virulence genes, is a topic that needs further investigation.
空弯曲杆菌是一种新兴的人畜共患病食源性和水源性病原体，可导致人类腹泻。全球空弯曲杆菌感染的流行情况被低估了，人们对其表型和基因型特征知之甚少。本研究旨在确定空弯曲杆菌分离株的抗菌药物敏感性（AST）谱，检测相关毒力基因，并对从人粪便和食物样本中获得的空弯曲杆菌分离株进行序列型（ST）分类。从泰国的人腹泻（n=25）、非腹泻（n=24）粪便和食物（n=35）样本中获得了 84 株空弯曲杆菌分离株。通过传统的微生物学程序进行表型鉴定，通过 Kirby-Bauer 圆盘扩散法进行 AST 检测以及毒力基因检测来评估它们。根据毒力基因和 AST 谱的存在，从每个来源选择具有代表性的分离株，以通过多位点序列分型（MLST）分析遗传多样性。所有分离株均显示出对萘啶酸 40.5%（34/84）、环丙沙星 11.9%（10/84）、阿奇霉素 8.3%（7/84）和红霉素 3.6%（3/84）的耐药性。在所检测的 10 个毒力基因中，cj1349、mviN 和 pldA 的检出率最高，为 100%（84/84），其次是 tlyA，为 98.8%（83/84），cadF，为 97.6%（82/84），ciaB，为 71.4%（60/84），hecA 和 hecB，为 22.6%（19/84），iroE，为 15.5%（13/84），irgA，为 10.7%（9/84）。人腹泻粪便和食物样本中的空弯曲杆菌分离株存在 3 个毒力基因，且分离株之间存在显著差异；hecB[36%（9/25）和 8.6%（3/35）]、hecA[36%（9/25）和 5.7%（2/35）]和 irgA[24%（6/25）和 2.9%（1/35）]（p<0.05）。hecA 和 hecB 毒力基因的功能与溶血机制有关，而 irgA 则支持细菌的营养需求。对 26 株空弯曲杆菌分离株的 MLST 分析显示，16 个新的 ST 表现出高度的遗传多样性。本研究结果有助于了解泰国可能具有致病性和耐药性的空弯曲杆菌。hecB、hecA 和 irgA 等致病毒力标记物有可能开发用于人腹泻粪便的快速诊断检测。未观察到 ST 与来源之间存在显著关系。空弯曲杆菌的作用机制尚不清楚，这是一个需要进一步研究的课题。
