Multi-locus sequence typing of Laribacter hongkongensis isolates from freshwater animals, environment and diarrhea patients in southern China.
Laribacter hongkongensis is a novel emerging bacterium associated with gastroenteritis and invasive bacteremic infections. Freshwater fish and edible frogs have been identified as major reservoirs of L. hongkongensis. Currently one of the main challenges in L. hongkongensis research is to identify their sources and possible transmission routes. The aim of this study was to determine the genetic diversity and relatedness of these L. hongkongensis isolates to their hosts in the hope of shedding light on these issues. In this study, multi-locus sequence typing (MLST) was used to determine the genetic characteristics of 114 L. hongkongensis strains, including 113 isolated from humans, fish, frogs, Amazonian snails and water sample in Guangzhou and Jiangmen, Southern China, and one reference isolate HZ242, recovered from a diarrhea patient in Hangzhou. The relationships among the STs and the relatedness among the isolates were assessed by phylogenetic and eBURST analysis. A total of 72 different sequence types (STs) from 114 isolates of L. hongkongensis were identified by MLST analysis, and ST99-ST161were novel. Significant difference of the prevalence of different STs between fish isolates (41.8%, 23/55) and frog isolates (82.4%, 42/51) was revealed (p=0.000). The most frequent ST (ST45) was identified 28 times and only found in fish isolates. In addition, 10 groups were identified by eBURST in this study. Combined the MLST data from Hong Kong and the present study, there were eight eBRUST lineages (group A-H) included the isolates (49.2%, 128/260) from either numerous hosts or multiple geographic origins, which contained 33.1% (53/160) of all the STs. Group A (n=57, STs=20) consisted exclusively of isolates from fish and 92.9% (39/42) of isolates in group B (n=42, STs=16) were only from fish. Group C-F (n=22, STs=14) were found to be associated with human, apart from other hosts. In this study, extensive genetic heterogeneity among the L. hongkongensis isolates from various hosts was observed. Specifically, there is higher genetic diversity of L. hongkongensis isolates of frog-origin than those of fish-origin. This study indicated some isolates exhibited a preference for specific hosts or geographic areas. ST45 was revealed to be the most frequent ST, which was only found in the fish isolates in Southern China, but might be irrelative to human infection. This MLST study further revealed that frog was likely to be another major source for human infection with L. hongkongensis apart from fish.
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China.
Zhiyun
Z
Wang
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China.
Jiangfeng
J
Zhu
Department of Infectious Disease, Nanfang Hospital, Guangzhou 510515, China.
Zhihua
Z
Liu
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China.
Youzhao
Y
Liu
Jiangmen Center for Disease Control and Prevention, Jiangmen 529000, China.
Nancai
N
Zheng
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China.
Mei
M
Feng
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China.
Qing
Q
Chen
Department of Nutrition and Food Hygiene, Southern Medical University, Guangzhou 510515, China.
Weijun
W
Yu
Guangxi Center for Disease Control and Prevention, Nanning 530028, China.
Lina
L
Jiang
Department of Epidemiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou 510515, China. Electronic address: hjalzh@smu.edu.cn.
Jing
J
Hu
D000818:Animals; D015373:Bacterial Typing Techniques; D002681:China; D019295:Computational Biology; D003967:Diarrhea / Q000382:microbiology*; D005399:Fishes / Q000382:microbiology*; D005618:Fresh Water / Q000382:microbiology*; D005759:Gastroenteritis / Q000382:microbiology; D006801:Humans; D058885:Multilocus Sequence Typing; D009346:Neisseriaceae / Q000145:classification*; D010802:Phylogeny
Diarrhea; Freshwater animals; Housekeeping gene; Laribacter hongkongensis; Multi-locus sequence typing