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Azithromycin resistance in Shigella spp. in Southeast Asia.

Darton, Thomas C, Thanh Tuyen, Ha, Chung The, Hao, Newton, Paul N, Dance, David A B, Phetsouvanh, Rattanaphone, Davong, Viengmon, Campbell, James I, Minh Hoang, Nguyen Van, Thwaites, Guy E, Parry, Christopher, Pham Thanh, Duy and Baker, Stephen (2018) 'Azithromycin resistance in Shigella spp. in Southeast Asia.'. Antimicrobial Agents and Chemotherapy, Vol 62, Issue 4, e01748-17.

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Abstract

Infection by Shigella spp. is a common cause of dysentery in Southeast Asia. Antimicrobials are thought to be beneficial for treatment, however antimicrobial resistance in Shigella spp. is becoming widespread. We aimed to assess the frequency and mechanisms associated with decreased susceptibility to azithromycin in Southeast Asian Shigella isolates and use these data to assess appropriate susceptibility breakpoints. Shigella isolated in Vietnam and Laos were screened for susceptibility against azithromycin (15μg) by disc diffusion and minimum inhibitory concentration (MIC). Phenotypic resistance was confirmed by PCR amplification of macrolide resistance loci. We compared the genetic relationships and plasmid contents of azithromycin resistant S. sonnei using whole genome sequences. From 475 available Shigella spp. isolated in Vietnam and Laos between 1994 and 2012, 6/181 S. flexneri (3.3%, MIC≥16g/L) and 16/294 S. sonnei (5.4%, MIC≥32g/L) were phenotypically resistant to azithromycin. PCR amplification confirmed a resistance mechanism in 22/475 (4.6%) isolates (19 mphA and 3 ermB). Susceptibility data demonstrated the acceptability of S. flexneri (MIC≥16g/L, zone≤15mm) and S. sonnei (MIC≥32g/L, zone≤11mm) breakpoints with <3% discrepancy. Phylogenetic analysis demonstrated that decreased susceptibility has arisen sporadically in Vietnamese S. sonnei 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 clinical outcome. The potential emergence of azithromycin resistance highlights the need for alternative management options for Shigella infections in endemic countries. [Abstract copyright: Copyright © 2018 Darton et al.]

Item Type: Article
Subjects: QV Pharmacology > Anti-Bacterial Agents. Tissue Extracts > QV 350 Anti-bacterial agents (General or not elsewhere classified)
QV Pharmacology > Anti-Bacterial Agents. Tissue Extracts > QV 350.5 Specific drugs, A-Z
QW Microbiology and Immunology > Bacteria > QW 138 Enterobacteriaceae
QW Microbiology and Immunology > QW 45 Microbial drug resistance. General or not elsewhere classified.
WA Public Health > WA 30 Socioeconomic factors in public health (General)
Faculty: Department: Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI): https://doi.org/10.1128/AAC.01748-17
SWORD Depositor: JISC Pubrouter
Depositing User: Stacy Murtagh
Date Deposited: 12 Feb 2018 16:23
Last Modified: 12 Apr 2018 13:36
URI: https://archive.lstmed.ac.uk/id/eprint/8215

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