Azithromycin Resistance in Shigella spp. in Southeast Asia.

Darton, Thomas C ORCID: 0000-0003-2209-9956, Tuyen, Ha Thanh, The, Hao Chung, Newton, Paul N ORCID: 0000-0002-4608-6431, Dance, David AB ORCID: 0000-0001-9189-7244, Phetsouvanh, Rattanaphone, Davong, Viengmon, Campbell, James I, Hoang, Nguyen Van Minh, Thwaites, Guy E ORCID: 0000-0002-2858-2087
et al (show 3 more authors) (2018) Azithromycin Resistance in Shigella spp. in Southeast Asia. Antimicrobial agents and chemotherapy, 62 (4). e01748-e01717.

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Infection by <i>Shigella</i> spp. is a common cause of dysentery in Southeast Asia. Antimicrobials are thought to be beneficial for treatment; however, antimicrobial resistance in <i>Shigella</i> spp. is becoming widespread. We aimed to assess the frequency and mechanisms associated with decreased susceptibility to azithromycin in Southeast Asian <i>Shigella</i> isolates and use these data to assess appropriate susceptibility breakpoints. <i>Shigella</i> 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 <i>Shigella sonnei</i> isolates using whole-genome sequences. From 475 available <i>Shigella</i> spp. isolated in Vietnam and Laos between 1994 and 2012, 6/181 <i>S. flexneri</i> isolates (3.3%, MIC ≥ 16 g/liter) and 16/294 <i>S. sonnei</i> isolates (5.4%, MIC ≥ 32 g/liter) were phenotypically resistant to azithromycin. PCR amplification confirmed a resistance mechanism in 22/475 (4.6%) isolates (<i>mphA</i> in 19 isolates and <i>ermB</i> in 3 isolates). The susceptibility data demonstrated the acceptability of the <i>S. flexneri</i> (MIC ≥ 16 g/liter, zone diameter ≤ 15 mm) and <i>S. sonnei</i> (MIC ≥ 32 g/liter, zone diameter ≤ 11 mm) breakpoints with a <3% discrepancy. Phylogenetic analysis demonstrated that decreased susceptibility has arisen sporadically in Vietnamese <i>S. sonnei</i> 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 <i>Shigella</i> infections in countries where <i>Shigella</i> is endemic.

Item Type: Article
Uncontrolled Keywords: Shigella, Shigella flexneri, Shigella sonnei, Dysentery, Bacillary, Azithromycin, Anti-Bacterial Agents, Microbial Sensitivity Tests, Phylogeny, Drug Resistance, Bacterial, Drug Resistance, Multiple, Bacterial, Asia, Southeastern
Depositing User: Symplectic Admin
Date Deposited: 17 May 2019 10:54
Last Modified: 19 Jan 2023 00:45
DOI: 10.1128/aac.01748-17
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