Objective        To establish a method for rapid detection of Escherichia coli O157∶H7

Shigella flexneri

Campylobacter jejuni and Vibrio parahaemolyticus based on immunomagnetic bead and multiplex PCR.       Methods        Multiplex PCR primers were designed and synthesized respectively according to the fragment sequences of uidA gene from Escherichia coli O157∶H7

ipaH gene from Shigella flexneri

hipo gene from Campylobacter jejuni and tlh gene from Vibrio parahaemolyticus. By optimizing the process of immunomagnetic bead separation and multiplex PCR strategies

multiplex PCR was used to amplify the 4 target genes of above pathogens. And the sensitivity and specificity of the detection system were identified.       Results        The amplification efficiency was highest when the magnesium ions concentration was 4 mmol/L. The sensitivity for rapid detecting Escherichia coli O157∶H7 was 2.7×10 cfu/ml

for Shigella flexneri was 6.4×10 cfu/ml

for Campylobacter jejuni was 7.6×10 cfu/ml

and for Vibrio parahaemolyticus was 3.6×10 cfu/ml.       Conclusion        An immunomagnetic bead and multiplex PCR detection system for above 4 pathogens is successfully established

with strong specificity

high sensitivity

simple procedures and high efficiency in diagnosis of infectious diarrhea.