Cheila Minéia Daniel de Paula

ANTIMICROBIAL RESISTANCE AND PCR-RIBOTYPING OF SHIGELLA RESPONSIBLE FOR FOODBORNE OUTBREAKS OCCURRED IN SOUTHERN BRAZIL

Little information about Shigella responsible for foodborne shigellosis is available in Brazil. The present study aimed to investigate the antimicrobial resistance and PCR-ribotyping patterns of Shigella isolates responsible for foodborne outbreaks occurred in Rio Grande do Sul State (RS), Southern Brazil in the period between 2003 and 2007. Shigella strains (n=152) were isolated from foods and fecal samples of victims of shigellosis outbreaks investigated by the Surveillance Service. Identification of the strains at specie level indicated that 71.1% of them were S. flexneri, 21.5% S. sonnei, and 0.7% S. dysenteriae. Ten strains (6.7%) were identified only as Shigella spp. An increasing occurrence of S. sonnei was observed after 2004. Most of the strains were resistant to streptomycin (88.6%), followed by ampicillin (84.6%), and sulfamethoxazole/trimethoprim (80.5 %). Resistant strains belonged to 73 patterns, and pattern A (resistance to ampicillin, sulfamethoxazole/trimethoprim, tetracycline, streptomycin, chloramphenicol, and intermediate resistance to kanamycin) grouped the largest number of isolates (n=36). PCR-ribotyping identified three banding patterns (SH1, SH2, and SH3). SH1 grouped all S. flexneri and SH2 grouped all S. sonnei. The S. dysenteriae strain belonged to group SH3. According to the results, several Shigella isolates shared the same PCR-rybotyping banding pattern and the same resistance profile, suggesting that closely related strains were responsible for the outbreaks. However, other molecular typing methods need to be applied to confirm the clonal relationship of these isolates.

Genotypic and antimicrobial characterization of pathogenic bacteria at different stages of cattle slaughtering in southern Brazil

Meat can be contaminated in different stages of the slaughtering process and the identification of these stages is the starting point to implement adequate control measures. The objectives of this study were to assess the presence of pathogenic microorganisms in cattle carcasses, to identify the most important contamination points of the slaughtering process, and to evaluate the possible risk factors related to them in a cattle slaughterhouse. To this aim, 108 cattle carcasses were sampled at three stages of the slaughtering process: Point 1 (hides after bleeding); Point 2 (carcasses after hide removal); and Point 3 (carcasses immediately after division). Escherichia coli O157:H7, Listeria monocytogenes and Salmonella Livingstone were isolated from the carcasses. Phenotypic and genotypic characterization indicated that there was cross-contamination among animals, since bacteria with identical genotypic and phenotypic profiles were isolated from different animals at the same sampling day. Furthermore, this is the first report about the isolation of E. coli O157:H7 in a bovine slaughterhouse from southern Brazil.