Isolation and identification of Escherichia coli O157∶H7 from cow and its biological characteristics / 中国人兽共患病学报

ABSTRACT

To understand the Escherichia coli (E .coli) O157∶ H7 isolated from cow in Zhengzhou ,Henan Province ,a total of 146 samples of cow fecal and milk were collected in the different farms ,and E .coli O157∶ H7 was detected with mul-tiplex polymerase chain reaction (PCR) in our laboratory .Then the biochemical characteristics ,growth dynamic ,the biofilm formation ,and the toxin genes of the E .coli O157∶ H7 isolates were analyzed .The results showed that 2 strains of E .coli O157∶H7 were found ,with the detection rate of 1 .4% ,and the isolates were named as L1 and L2 in current study ,respec-tively .The E .coli O157∶H7 clinical isolates had the same biochemical characteristics with that of the typical E .coli .The L1 and L2 isolates presented similar growth curve ,which entered into the log phase earlier than that of the standard strain .L1 strain formed thick ,confluent ,complete biofilm after 48 hours post-inoculation ,and the biofilm of L2 strain was formed com-pletely in 36 hours .The two E .coli O157∶ H7 isolates were positive with eaeA and hlyA genes ,and the L1 strain also carried the Stx2 virulence gene .Our results reinforce the epidemiological data of E .coli O157∶H7 ,and underscore the need for more effective surveillance of animal-derived E .coli O157∶H7 isolates in Zhengzhou City ,China .