DataSheet1.XLSX

Non-human primates (NHPs) for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in the family Enterobacteriaceae. In this study, five individual isolates of multi-drug resistant Shigella flexneri were isolated from the feces of three macaques. Antibiotic susceptibility testing confirmed resistance or decreased susceptibility to ampicillin, amoxicillin-clavulanic acid, cephalosporins, gentamicin, tetracycline, ciprofloxacin, enrofloxacin, levofloxacin, and nalidixic acid. S. flexneri isolates were susceptible to trimethoprim-sulfamethoxazole, and this drug was used to eradicate infection in two of the macaques. Plasmid DNA from all isolates was positive for the plasmid-encoded quinolone resistance gene qnrS, but not qnrA and qnrB. Conjugation and transformation of plasmid DNA from several S. flexneri isolates into antibiotic-susceptible Escherichia coli strains conferred the recipients with resistance or decreased susceptibility to quinolones and beta-lactams. Genome sequencing of two representative S. flexneri isolates identified the qnrS gene on a plasmid-like contig. These contigs showed >99% homology to plasmid sequences previously characterized from quinolone-resistant Shigella flexneri 2a and Salmonella enterica strains. Other antibiotic resistance genes and virulence factor genes were also identified in chromosome and plasmid sequences in these genomes. The findings from this study indicate macaques harbor pathogenic S. flexneri strains with chromosomally- and plasmid-encoded antibiotic resistance genes. To our knowledge, this is the first report of plasmid-mediated quinolone resistance in S. flexneri isolated from NHPs and warrants isolation and antibiotic testing of enteric pathogens before treating macaques with quinolones prophylactically or therapeutically.

用于生物医学研究的非人灵长类动物（Non-human primates, NHPs）通常会感染志贺氏菌属（Shigella spp.），该菌可引发急性痢疾或慢性间歇性腹泻。这类动物常通过喹诺酮类抗生素（quinolone antibiotics）进行预防性与临床治疗，以根除此类潜在感染。然而，染色体介导与质粒介导的抗生素耐药性已成为肠杆菌科（Enterobacteriaceae）物种日益受到关注的问题。本研究从3只猕猴的粪便样本中分离得到5株独立的多重耐药福氏志贺氏菌（Shigella flexneri）菌株。药敏试验证实，这些菌株对氨苄西林（ampicillin）、阿莫西林-克拉维酸（amoxicillin-clavulanic acid）、头孢菌素类（cephalosporins）、庆大霉素（gentamicin）、四环素（tetracycline）、环丙沙星（ciprofloxacin）、恩诺沙星（enrofloxacin）、左氧氟沙星（levofloxacin）以及萘啶酸（nalidixic acid）均表现出耐药性或敏感性降低。福氏志贺氏菌菌株对甲氧苄啶-磺胺甲恶唑（trimethoprim-sulfamethoxazole）敏感，该药物被用于根除其中2只猕猴的感染。所有分离株的质粒DNA（plasmid DNA）均携带质粒编码的喹诺酮耐药基因qnrS，但未检出qnrA与qnrB。将部分福氏志贺氏菌菌株的质粒DNA通过接合与转化（Conjugation and transformation）导入药敏性大肠杆菌（Escherichia coli）菌株后，受体菌株可获得对喹诺酮类与β-内酰胺类抗生素的耐药性或敏感性降低。对2株代表性福氏志贺氏菌分离株进行基因组测序后，在类质粒重叠群上发现了qnrS基因。这些重叠群与此前从喹诺酮耐药福氏志贺氏菌2a株及肠炎沙门氏菌（Salmonella enterica）菌株中鉴定的质粒序列同源性超过99%。在这些菌株的染色体与质粒序列中，还鉴定出其他抗生素耐药基因与毒力因子基因（virulence factor genes）。本研究结果表明，猕猴携带同时携带染色体编码与质粒编码抗生素耐药基因的致病性福氏志贺氏菌菌株。据我们所知，这是首次报道从非人灵长类动物中分离的福氏志贺氏菌中存在质粒介导的喹诺酮类耐药性，该结果提示在对猕猴使用喹诺酮类抗生素进行预防性或治疗性治疗前，需对肠道病原体（enteric pathogens）进行分离与药敏检测。