Virulence factors in Escherichia coli strains and phenotypic and genotypic charact...
| Grant number: | 10/07136-7 |
| Support type: | Regular Research Grants |
| Duration: | August 01, 2010 - July 31, 2012 |
| Field of knowledge: | Agronomical Sciences - Veterinary Medicine |
| Principal Investigator: | Antonio Fernando Pestana de Castro |
| Grantee: | Antonio Fernando Pestana de Castro |
| Home Institution: | Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Assoc. researchers: | Marcelo Palma Sircili ; Nilton Erbet Lincopan Huenuman |
Abstract
Strains of Escherichia coli with resistance or variable sensitivity to several cephalosporins of 3rd generation have been detected in human beings and animals all around the world. These strains produce beta- lactamases of broad spectrum (ESLBs- extended spectrum beta-lactamases). In nowadays more than 200 types of beta-lactamases are known, being important to stress that several Gram-negative are ESLBs producers, that are plasmid encoded. In the last years, the emergence of a new group of ESLBs, encoded by plasmids found in strains of human and animal origin, have called the attention of scientists of all the world. Most ESBLs belong to the classification A (Amber) and are derived of the parental enzymes TEM and SHV, on account of very a single mutation in the active site of the beta-lactamases. The genes that encode the ESBLs are found into the plasmids of high molecular weight that also contain resistance markers to further antimicrobials and therefore they will provide multiple resistances to several antimicrobial drugs, including aminoglycosides and cotrimoxazol. There is one group of Escherichia coli that produces enzymes of the CTX-M type which has been reported as important agent of urinary tract infection (UTI). With regard to Brazil the strains producing ESBLs have been isolated in hospitals, sewage effluents of hospitals, meat of exported chicken and acute infection among people of the community. Several investigations identified this group in animals and strains of human origin confirmed the presence of ESBLs belonging to CTX-M, including the clone CTM-15 O25b: H4-ST131. This clone is responsible in nowadays by the high number of infections caused by this clone all around the world. In Brazil, although there are several reports of cases among the human population no reports have been fund among animals. Conversely, in other countries, such as Germany, Holland, France, Denmark and Spain the clone CTM-X-15 O25:H4-ST131 has been detected among animals. So, this research will look for the presence of the clone CTM-X-15 O25:H4-ST131 as well as further ESBLs (TEM, SHV and OXA) using PCR techniques and also phenotypic methods, among E. coli strains from dogs, cats, chickens and ground chicken meat obtained from slaughtered and butcher shops. This search also has one of the objectives to look for gene that encode virulence factors found in our countries comparing the data obtained in other countries, verifying the antimicrobial profile of the isolates and also to analyze the adhesion pattern on HEp-2 cells and finally to assay the lethal potentiality according to tests assayed into mice. Diversity among ESBLs strains will be made by PFGE and MLST. (AU)