Volume 100, Issue 5
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Leptospirosis is a global zoonotic disease caused by pathogenic bacteria of the genus, which are fastidious, slow-growing organisms. Antimicrobial susceptibility data are limited; traditionally, the organisms have not been culturable on solid media. The recent development of Vanaporn Wuthiekanun (LVW) agar, which facilitates rapid growth of spp., provides the opportunity for antimicrobial susceptibility testing. Eighty-three spp. clinical isolates originating from patients in Laos between 2006 and 2016 were tested against six antimicrobials (azithromycin, ceftriaxone, ciprofloxacin, doxycycline, gentamicin, and penicillin G) using disk diffusion on LVW agar. Quality control was undertaken using American Type Culture Collection (ATCC) reference strains with known susceptibilities on both standard media and LVW agar. All spp. isolates produced large zones of inhibition around each of the six antimicrobials. All zones were greater than 25 mm: gentamicin produced the smallest zones (median 35 mm; interquartile range 30 mm–37 mm) and azithromycin produced the largest zones (median 85 mm; interquartile range 85 mm–85 mm). Zones produced by non-leptospiral ATCC reference strains on LVW agar were within 2 mm of accepted strain-specific quality control range on standard media. Antimicrobial activity on LVW agar appears to be similar to that on standard media. As there are no published susceptibility guidelines for the genus, zone interpretation was subjective. Vanaporn Wuthiekanun agar enabled antimicrobial susceptibility testing of multiple isolates on solid media; the large zone sizes observed suggest that resistance has not emerged to these six antimicrobials in Lao spp.

[open-access] This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


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Supplemental material

  • Received : 30 Nov 2018
  • Accepted : 03 Feb 2019
  • Published online : 18 Mar 2019

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