Study On Serum Type, Drug Resistance And Gene Typing Of Escherichia Coli. From Chongqing' Piglet

Pathogenic Escherichia coli (E.coli.) is an important pathogen bacterial of yellow and white sour of piglet. In recent years, the resistance of E.coli to antimicrobial agents has been rapidly increasing in many countries of the world. Up to now, in many countries and areas, plenty data on resistance and serotype distribution of E.coli has been collected; besides, spread of E.coli resistance was investigated by various molecular biology methods. These data contributed a great deal in treatment and prevention of E.coli infection. However, few data of E.coli has been reported regarding the prevalence and spread of E.coli resistance in Chongqing. We collected clinical isolates and carriage strains of E.coli in Chongqing, determined the drug resistance sero types and. gene typing。To make a comparison of between the results of gene typing and the results phenotype (serotypes typing and drug resistance).1. Isolation and serotyping of E.coliThe piglet corpses, seemingly by yellow and white sour of piglet E. coh, were collected from 8 district in Chongqing. Samples included blood from the dead piglet's heart, liver and the excrement type of anus wipe, and were obtained sterilely for the use of isolation of pathogen. 173 pathogenic strains of E.coli had been identified from these farms. All the strains were investigated on some of their biological characteristics, including biochemical reaction, pathogenicity for mouse。In the 173 strains, 91 isolates could be indentificated serotype with onovalence anti-O antigen antibodies of E.coli which belonged to 17 serotypes. the predominant types are O₁₀₁(16.5ï¼…), O₈ (15.4ï¼…), O₂₀ (12.1ï¼…), O₆₄(11.0ï¼…), O₄₅ (8.8ï¼…) and O₁₄₉(7.6ï¼…). There are many kinds of serogroups in the same district and their own predominant types in most of districts. Some predominant serogroups in different Districts are identical, others are different. Besides, there are 12 other serum types such as 0₂, 0₉, 0₅₄, 0₆₀, 0₈₉, 0₁₁₁, 0₁₁₉, 0₁₃₇, 0₁₃₈, 0₁₄₁, 0₁₄₇, etc. The analysis between serum types and drug resistance showed no direct internal relationship.2. Antimicrobial susceptibility test of pathogenic E.coli.173 pathogenic strains in vitro drug sensitivity tests were carried out by paper diffusion method(namely Kirby-Bauer bacterium culture diffusion method)recommended .Results show that there exit(are)132 kinds of drug resistance spectrums existed. The isolates showed resistance to 25 drugs at most while 9 drugs at least, most of them have had cross resistance to many medicine and showed multiple resistance tO drugs clinically widely used such aspenicillin, compound radonil and quadracycline tetracyclines, etc. the most sensitive antibiotic was cefradine (150/173), the second one was cefoperazone (134/173), the others were in tumgentamycin, cefazolin, amikacin, tubramycin, cephalexin, neomycin, gentamicin, streptomycin, kamanycin, ofloxacin, norfloxacin, ciprofl oxacin, furazolidone, chloramphonicol, amoxicillin, polymyxin B. The tested E. coli strains have drug resistance and multi-resistance mainly.The strains showed the least resistence to 9 kinds of antibiotics;the most resistence to 25 kinds of antibiotics. All of the tested E.coli are resistence to 10 kinds of antibiotics (28.8ï¼…), 22 kinds of antibiotics (12.7ï¼…), 19 kinds of antibiotics (11.6ï¼…), 20 kinds of antibiotics (11.6ï¼…), 21 kinds of antibiotics (11ï¼…), 15 kinds of antibiotics (8.1ï¼…), 13 kinds of antibiotics (6.4ï¼…), 18 kinds of antibiotics (5.8ï¼…), 12 kinds of antibiotics (5.2ï¼…), 17 kinds of antibiotics (4.6ï¼…), 14 kinds of antibiotics (3.5ï¼…), 23 kinds of antibiotics (3.5ï¼…), 24 kinds of antibiotics (1.7ï¼…). 25 kinds of antibiotics (1.7ï¼…), 9 kinds of antibiotics (1.7ï¼…).3 Study on gene typing of E.coli. and comparison between the gene type and the phenotypePulse field get electrophoresis (PFGE) was for the gene typing of E.coli., We have conducted the following research: comparison of between the results of gene typing and the results of phenotype (serotypes typing and drug resistance). 91 strains E.coli isolates were typed by the pilsed-field gel electrophoresis(PFGE). 68 strains scattering in different district were classified to 4 type by PFGE.60 strains in the A group could be further divided into Al, A2 and A3 subtypes. 27 strains were included in Al, 10 strains were included in A2,23 strains were included in A3.There were no correlation between antibiogram, serotype and PFGE.