BMC Microbiology (Jan 2009)

Development of a multi-locus sequence typing scheme for <it>Laribacter hongkongensis</it>, a novel bacterium associated with freshwater fish-borne gastroenteritis and traveler's diarrhea

  • Lee Edwin KY,
  • Chan King-Man,
  • Tsang Vivien YM,
  • Tse Herman,
  • Tsang Alan KL,
  • Teng Jade LL,
  • Woo Patrick CY,
  • Chan Jim KH,
  • Ma Shirley SL,
  • Tam Dorothy MW,
  • Chung Liliane MW,
  • Lau Susanna KP,
  • Yuen Kwok-Yung

DOI
https://doi.org/10.1186/1471-2180-9-21
Journal volume & issue
Vol. 9, no. 1
p. 21

Abstract

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Abstract Background Laribacter hongkongensis is a newly discovered, facultative anaerobic, Gram-negative, motile, sea gull-shaped rod associated with freshwater fish borne gastroenteritis and traveler's diarrhea. A highly reproducible and discriminative typing system is essential for better understanding of the epidemiology of L. hongkongensis. In this study, a multilocus sequence typing (MLST) system was developed for L. hongkongensis. The system was used to characterize 146 L. hongkongensis isolates, including 39 from humans and 107 from fish. Results Fragments (362 to 504 bp) of seven housekeeping genes were amplified and sequenced. Among the 3068 bp of the seven loci, 332 polymorphic sites were observed. The median number of alleles at each locus was 34 [range 22 (ilvC) to 45 (thiC)]. All seven genes showed very low dn/ds ratios of ISA) measurement showed significant linkage disequilibrium in isolates from both humans and fish. The ISA for the isolates from humans and fish were 0.270 and 0.636, indicating the isolates from fish were more clonal than the isolates from humans. Only one interconnected network (acnB) was detected in the split graphs. The P-value (P = 0) of sum of the squares of condensed fragments in Sawyer's test showed evidence of intragenic recombination in the rho, acnB and thiC loci, but the P-value (P = 1) of maximum condensed fragment in these gene loci did not show evidence of intragenic recombination. Congruence analysis showed that all the pairwise comparisons of the 7 MLST loci were incongruent, indicating that recombination played a substantial role in the evolution of L. hongkongensis. A website for L. hongkongensis MLST was set up and can be accessed at http://mlstdb.hku.hk:14206/MLST_index.html. Conclusion A highly reproducible and discriminative MLST system was developed for L. hongkongensis.