In order to study the occurence and transmission of airborne microorganism，a model to estimate spread of the airborne microorganism was established in this study by giving chicken with culture medium contain E. coli JM109 strain marked with green fluorescent protein. Air samples, including pen and outside of the pen air (2 and 5 m as well as 10, 20 m away) of chicken house were collected using sixstage Andersen microbial samplers. E. coli JM109pGFP concentrations (CFU·m3 air) collected from different sampling sites were calculated.Through the E. coli JM109pGFP obtained from different sampling sites the spreading of bioaerosol from animal houses to the ambient air was characterized. After drinking E. coli JM109pGFP culture medium half an hour，chicken excreted feces containing E. coli JM109pGFP,at the same time the isolated E. coli JM109pGFP concentrations in pen air and outside sites of the pen (2 and 5 m as well as 10, 20 m away) were reached top concentrations，were 1531×103,8080×102,3360×102,2250×102,6600×10 CFU·m-3，but there were no significant difference between the inside and the outside sites of the pen (P>005).After 30 h, E. coli JM109pGFP concentration was 7 CFU·m-3, E. coli JM109pGFP wasn’t detected in other sites. After 36 h,E. coli JM109pGFP disappeared in pen air.Our results suggested that E. coli JM109pGFP isolated from pen air and outside of the pen air originated in the chicken feces and the microbiological aerosols in the chicken house were transmitted by air exchanging to the surroundings，so it could cause environmental microbiological pollution to some extents.

To investigate the genotype distribution of ESBLs and AmpC βlactamases among Escherichia coli isolated from farm animals in Chongqing City, 192 strains of E. coli isolated from piglets with diarrhea, 65 strains of E. coli isolated from cattles with mastitis and 69 strains of E. coli isolated from chickens were detected.19 strains of E. coliproducing ESBLs and 6 strains of E. coliproducing AmpC βlactamases were screened by preliminary screening and phenotypic confirming, and genotype distribution of ESBLs and AmpC βlactamases were analyzed by PCR and sequencing. In Chongqing area, the genotype positive rate of TEM, CTXM, DHA1 and CMY2 was 215%, 521%, 061% and 061% among E. coli isolated from farm animals. Of which, 5 strains of E. coli were found to carry two kinds of genotype. But, DHA1 genotype was first detected from veterinary clinic in China, its GenBank accession number was FJ386455. The results indicated that TEM and CTXM are major genotype in Chongqing, and E. coliproducing βlactamases had multiresistance, it deserve more attention in veterinary clinic.