Study On Isolation And Identification Of Escherichia Coli Caused Piglets Diarrhea And Partial Characteristics Of Bacterial Isolates

Piglet diarrhea usually occurred in piglets less than 3 weeks of age caused by pathogenic Escherichia coli which is one of the major pathogens. This disease caused serious health hazards to piglets. Because the serological types of Escherichia coli were multitudinous, which could influence the specific vaccine development and application for preventing and control of Escherichia coli infections. In addition the cross immune protection of various serological types of Escherichia coli was poor, the measures are difficult to make in preventing and controlling this disease. A high incidence and mortality of diseased piglets caused with Escherichia coli caused economic losses to swine industry. There are important measures in preventing and control Escherichia coli diarrhea in swine by bacteria isolation and identification, serotyping identification, drug susceptibility tests and detection of toxin factors ,all of them are useful on the vaccine development and high sensitivity antimicrobial agents selection.To find the dominant serotypes and major virulence factors of swine pathogenic Escherichia coli in swine population in Ningqiang county. Some works have been done in this study. The results are as follows:(1)20 E.coli were isolated from 60 anal swabs collected from suspected clinical cases of diarrhea piglets in 5 swine farms. All the 20 isolates were pathogenic Escherichia coli identified by colony morphology, Gram staining, cultural characteristics, biochemical tests and serological tests.(2)The serotype of 18 out of 20 isolates were identified which belonged to 7 swine Escherichia coli serotypes and 40% isolates were O8 serotype. The other serotype were O149 (1 strain), O60 (2 strains), O139 (2 strains), O20 (1 strain), O45 (1 strain) and O141 (1 strain) ,respectively.(3)Pathogenicity test results showed that the 9 isolates were pathogenic to experimental mice, the serotype of pathogenic isolates belonged to O8 (7 strains), O141 (1 strain) and O149(1 strain) respectively.(4)Isolates of serotype O8, O20, O45, O149 were sensitive to Cephradine, Bristol bacteria, and Ampicillin, serotype O60 was sensitive to Furazolidone, Cephradine and Bristol bacteria, O139 was sensitive to Ampicillin, O141 was sensitive to Norfloxacin and Ampicillin. O20 was high resistant to most selected antimicrobial agents, O45, O60, O139, O141 were resistant to the most selected antimicrobial agents, O8 was resistant to Norfloxacin and Kalamycin.(5)Virulence factors of isolates were determined with PCR and results showed that the isolates did not carry STa,STb,LT and SLT-2e virulence genes of E.coli.