Structure, function and regulation of the thermostable direct hemolysin (TDH) in pandemic Vibrio parahaemolyticus

Vibrio parahaemolyticus is a leading cause of seafood-associated bacterial gastroenteritis. The pathogen produces the thermostable direct hemolysin (TDH), which is the sole cause of the Kanagawa phenomenon (KP), a special β-type haemolysis in the Wagatsuma agar. TDH also exerts several other biological activities, the major includes lethal toxicity, cytotoxicity, and enterotoxicity. The structure and roles of TDH and the transcriptional regulation of tdh genes, are summarized in this review, which will give a better understanding of the pathogenesis of V. parahaemolyticus.

Acute Infectious Diarrhoea in Adults: Identifying Clinical Parameters Associated with Specific Pathogens

Introduction

Infectious diarrhoea may be caused by viral, bacterial or protozoan agents. The objective of this study was to explore the possibility of correlating presenting clinical and demographic features with the specific types of stool pathogens subsequently identified.

Materials & Methods

A retrospective study was performed in the setting of an Accident & Emergency (A&E) department of an urban acute-care hospital in Hong Kong. The inclusion criteria were adults (age ≥16); presentation with features of acute infectious diarrhoea; treated as out-patients with or without observation; and with stool cultures requested from A&E. All consecutive culture-positive cases (n=130) satisfying the above criteria were included. The control-group (n=119) consisted of a random sample of culture-negative cases during the same study period. For each of the six pathogens identified, statistical analyses were performed to compare differences in clinical features amongst three groups: (i) cases positive for the specific pathogen; (ii) cases positive for other pathogens; and (iii) cases with negative culture.

Results

Salmonella was associated with significantly higher body temperatures at presentation. Vibrio parahaemolyticus (VP) was associated with a significantly shorter duration of diarrhoea and of abdominal pain at presentation. Other variables were not helpful in predicting the type of stool pathogen.

Conclusion

In patients presenting with acute infectious diarrhoea in an A&E setting in Hong Kong, Salmonella and VP may be suspected according to the clinical features identified in this study.