The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield Medical School, Sheffield, United Kingdom.
Antimicrob Agents Chemother. 2018 Mar 27;62(4). doi: 10.1128/AAC.01748-17. Print 2018 Apr.
Infection by spp. is a common cause of dysentery in Southeast Asia. Antimicrobials are thought to be beneficial for treatment; however, antimicrobial resistance in spp. is becoming widespread. We aimed to assess the frequency and mechanisms associated with decreased susceptibility to azithromycin in Southeast Asian isolates and use these data to assess appropriate susceptibility breakpoints. isolates recovered in Vietnam and Laos were screened for susceptibility to azithromycin (15 μg) by disc diffusion and MIC. Phenotypic resistance was confirmed by PCR amplification of macrolide resistance loci. We compared the genetic relationships and plasmid contents of azithromycin-resistant isolates using whole-genome sequences. From 475 available spp. isolated in Vietnam and Laos between 1994 and 2012, 6/181 isolates (3.3%, MIC ≥ 16 g/liter) and 16/294 isolates (5.4%, MIC ≥ 32 g/liter) were phenotypically resistant to azithromycin. PCR amplification confirmed a resistance mechanism in 22/475 (4.6%) isolates ( in 19 isolates and in 3 isolates). The susceptibility data demonstrated the acceptability of the (MIC ≥ 16 g/liter, zone diameter ≤ 15 mm) and (MIC ≥ 32 g/liter, zone diameter ≤ 11 mm) breakpoints with a <3% discrepancy. Phylogenetic analysis demonstrated that decreased susceptibility has arisen sporadically in Vietnamese isolates on at least seven occasions between 2000 and 2009 but failed to become established. While the proposed susceptibility breakpoints may allow better recognition of resistant isolates, additional studies are required to assess the impact on the clinical outcome. The potential emergence of azithromycin resistance highlights the need for alternative options for management of infections in countries where is endemic.
spp. 感染是东南亚地区痢疾的常见病因。人们认为抗生素对治疗有益；然而， spp. 的抗生素耐药性正在广泛传播。我们旨在评估东南亚 分离株对阿奇霉素敏感性降低的频率和相关机制，并利用这些数据评估适当的药敏折点。我们通过纸片扩散法和 MIC 筛选法检测了越南和老挝采集的 分离株对阿奇霉素（15 μg）的敏感性。通过对大环内酯类耐药基因座的 PCR 扩增来确认表型耐药。我们使用全基因组序列比较了阿奇霉素耐药 分离株的遗传关系和质粒含量。在 1994 年至 2012 年间从越南和老挝获得的 475 株 spp. 中，有 6/181 株（3.3%，MIC≥16 g/l）和 16/294 株（5.4%，MIC≥32 g/l）对阿奇霉素表现出表型耐药。PCR 扩增证实了 22/475 株（4.6%）分离株存在耐药机制（19 株为 ，3 株为 ）。药敏数据表明，接受 （MIC≥16 g/l，抑菌环直径≤15 mm）和 （MIC≥32 g/l，抑菌环直径≤11 mm）折点，差异率<3%。系统发育分析表明，2000 年至 2009 年期间，至少有 7 次在越南 分离株中偶然出现了敏感性降低，但未能建立。虽然建议的药敏折点可能更好地识别耐药分离株，但还需要进一步研究来评估其对临床结果的影响。阿奇霉素耐药性的出现凸显了在 流行的国家中管理 感染需要替代选择的必要性。
