Pathogenetic characterization of Vibrio parahaemolyticus isolates from clinical and seafood sources.
A total of 216 Vibrio parahaemolyticus isolates from seafood and clinical samples in eastern China were investigated for their hemolytic and urea-producing phenotypes, presence of putative virulence genes tdh and trh. Twenty-one clinical isolates (84%, 21/25) and 3 seafood isolates (1.57%, 3/191) were tdh-positive while only 3 clinical isolates (12%) and 7 seafood isolates (3.66%) were positive for trh gene. We further examined the pathogenicity of selected V. parahaemolyticus isolates in in vitro and in vivo systems. The clinical isolates were apparently more enteropathogenic (74.26 per thousand vs 62.07 per thousand expressed as intestine/body weight ratio, P<0.01) and more virulent than their seafood counterparts to mice (log LD(50) 6.86 vs 7.40 via orogastric route, P<0.05). They were also more adherent to in vitro cultured cells and of higher cytotoxicity as measured by LDH release of the HeLa cells although there were no statistical differences. The tdh-positive V. parahaemolyticus isolates were of higher enteropathogenicity (P<0.05, 74.24 per thousand vs 60.55 per thousand) and more virulent (log LD(50) 6.55 vs 7.21 via intraperitoneal route, P<0.05) than tdh-negative isolates. The tdh-positive isolates were generally more cytotoxic and adhesive to the cultured cell lines as well. From the in vitro and in vivo pathogenicity profiles, trh-positive isolates seemed to line between tdh-positive isolates and those without tdh and trh. There were two isolates H8 and H10 from clinical cases having moderate enteropathogenicity and virulence to mice, but were tdh-negative yet trh-positive. These results seem to suggest that hemolysins TDH and/or TRH may not be necessarily the only virulence factors of pathogenic V. parahaemolyticus isolates.
Zhejiang University, Institute of Preventive Veterinary Medicine, Hangzhou, Zhejiang, China.
Khamphouth
K
Vongxay
Shuna
S
Wang
Xiaofeng
X
Zhang
Beibei
B
Wu
Hongxia
H
Hu
Zijiang
Z
Pan
Suyun
S
Chen
Weihuan
W
Fang
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D018938:Caco-2 Cells; D002681:China; D005260:Female; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006367:HeLa Cells; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000235:genetics*; D006801:Humans; D007928:Lethal Dose 50; D051379:Mice; D008813:Mice, Inbred ICR; D010802:Phylogeny; D017747:Seafood / Q000382:microbiology*; D014735:Vibrio Infections / Q000382:microbiology; D014736:Vibrio parahaemolyticus / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D037521:Virulence Factors; C088609:thermostable direct hemolysin-related hemolysin protein, Vibrio parahaemolyticus; C068489:thermostable direct hemolysin