Verocytotoxin-producing Escherichia coli infection: The Hong Kong experience.

Infection by verocytotoxin-producing Escherichia coli (VTEC) is prevalent in many parts of the world but relatively uncommon in Asia, except Japan. A territory wide screening for VTEC (April to August 1996) in diarrhoeal stool samples sent to six hospital microbiology laboratories in Hong Kong revealed only four isolates of VTEC and one isolate of E. coli O157:NM in 1003 specimens (incidence 0.5%). Two isolates carrying the verocytotoxin (VT) genes belonged to the O157:H7 serotype while the other two were non-O157. One non-toxigenic E. coli O157:NM was also isolated. All isolates positive for VT genes by polymerase chain reaction (PCR) were also positive for the Vero toxin assayed by the Vero cell culture. The 97 kDa eaeA outer membrane protein gene and 60 MDa fimbrial plasmid pcVD419 were present only in the two O157:H7 isolates. All patients presented with uncomplicated watery diarrhoea; no one suffered from haemorrhagic colitis or the haemolytic uraemic syndrome. All patients recovered uneventfully without antibiotic treatment. Although VTEC infection is still uncommon in Hong Kong, continued surveillance is essential to prevent future outbreaks.