Rapid diagnosis of ETEC and HPI-harboring Escherichia coli infection in newborn piglets with diarrhea

Abstract

Diarrhea is a common and important disease in industrial pig farms and the pathogenic Escherichia coli
infection is the main cause of morbidity and mortality in newborn piglets. The preliminary diagnoses on
this disease are mainly depending on clinical symptom and detailed body dissection. To further shorten
the diagnosis time and increase the determination efficiency for newborn piglet diarrhea caused by E.
coli, a rapid method was established based on the fast bacterial culturing followed by the PCR
examining for the virulence factor genes, such as enterotoxin ST1, ST2, LT1 and high pathogenicity
island (HPI). A total of 151 rectal swab samples were obtained from live diarrheic piglets from Jiangsu
province, China. Following the first cultivation in LB broth at 37°C for 6 h, all the samples were detected
by the PCR methods, and the data show that 95 cases (62.91%) were infected with HPI-harboring E. coli,
24 cases (15.89%) were infected with Enterotoxigenic E. coli (ETEC) and 14 cases (9.27%) were infected
with ETEC and HPI-harboring E. coli. In addition, 2660 bacteria isolates were picked from all the 133
bacterial cultures which contained HPI-harboring E. coli and/or ETEC and the data of PCR examination
determined that only 57 isolates were HPI-harboring E. coli, 20 were ETEC and 3 were both ETEC and
HPI-harboring E. coli. This research not only revealed that HPI-harboring E. coli and ETEC are the
prevalent pathogen of newborn piglet diarrhea, but also suggested that the method used in this study is
specific, easier and more rapid to perform in the diagnosis of the infection of diarrheagenic E. coli with
high accurate rate than the bacterial isolation and identification.