Marisa da Costa

COMPARISON OF DIFFERENT SELECTIVE ENRICHMENT STEPS TO ISOLATE SALMONELLA SP. FROM FECES OF FINISHING SWINE

A two-phase study was conducted to compare the efficacy of several enrichment selective-broth steps associated to different plating media for recovery of Salmonella sp. from finishing swine feces. In a first phase, Rappaport-Vassiliadis broth (RV) incubated at 42oC, Tetrathionate Muller-Kauffmann broth at 37oC (TMK37) and 42oC (TMK42), and Selenite Cystine broth (SC) at 37oC, in combination with three selective plating media Rambach agar (RA), Xylose-Lysine-Tergitol 4 agar (XLT4), and Brilliant-Green Phenol-Red Lactose Sucrose agar (VB) were compared for recovery of Salmonella from artificially contaminated swine feces. In a second phase, RV, TMK37, and TMK42, associated with XLT4 and VB , were tested with naturally contaminated swine feces. In this study RV, TMK42 and TMK37 were superior to SC for isolating Salmonella sp. from artificially contaminated feces. TMK42 and RV were more productive than TMK37 for recovery of Salmonella from naturally contaminated feces samples. Selectivity and indication capability of the plating media were remarkably affected by the selective enrichment step effectiveness. The TMK42/XLT4 association was the most sensitive and RV/XLT4 the most specific. The use of VB agar is also recommended to increase the likelihood of isolating atypical H 2S-late producing/ non-producing Salmonella. In this study RV and TMK42 were the most efficient selective enrichment for recovery of Salmonella sp. from swine feces.

Prevalência de Salmonella sp em suínos abatidos em frígoríficos do Rio Grande do Sul

Este estudo foi realizado com o objetivo de determinar a prevalencia de Salmonella sp em suinos abatidos em frigorificos sob inspecao federal no Rio Grande do Sul. Amostras de fezes e linfonodos foram coletadas em tres diferentes frigorificos no Estado. A partir da analise microbiologica das amostras de 300 animais, encontrou-se uma prevalencia de Salmonella sp de 55,66%, com 17,6% de isolamentos a partir dos linfonodos, 18,3% das fezes e 19,6% em ambos os materiais. Foram identificados 26 sorovares diferentes em 226 isolados de Salmonella sp. Os sorovares mais prevalentes foram: Typhimurium (24,3%), Agona (19,9%), Derby (13,2%) e Bredeney (12%). Estes resultados indicam a necessidade de implementar programas de controle com o objetivo de diminuir a prevalencia de animais portadores ao abate.

Non specific serological reactions in the diagnosis of bovine brucellosis: experimental oral infection of cattle with repeated doses of Yersinia enterocolitica O:9.

Eight heifers were orally infected with 4 x 10(9) colony forming units of a field cattle strain of Yersinia enterocolitica O:9 in a capsule, 5 days a week, for about 9 weeks (day 0-day 64 (D0-D64). The faecal shedding of Y. enterocolitica O:9 began on D5 for seven out of the eight challenged cattle with a high level of excretion during the first month, followed by a decrease till the day of slaughter (D76). Y. enterocolitica O:9 was not isolated from organs collected at slaughter. No clinical symptoms were observed. Hyperplasia of intestinal lymph formations was the sole microscopic lesions observed. Five animals showed a serological reaction against Brucella antigens in at least one of the following tests: Rose-Bengal test, complement fixation test, tube agglutination test or indirect ELISA (iELISA) tests. Only one animal showed a high level of serological response and a positive reaction in the dithiothreitol-microagglutination test. The observed variability in terms of individual sensitivity to the Y. enterocolitica O:9 infection is in agreement with the low individual prevalence rate and the transient serological reaction and faecal Y. entercolitica O:9 shedding observed in herds showing false positive serological reactions in brucellosis.

Ocorrência de Salmonella sp em suínos de terminação no Rio Grande do Sul

Pen feces samples were taken in ten finishing farms in Rio Grande do Sul (Brazil) and submitted to Salmonella isolation protocol. Two farms negative and one positive in the preliminary screening were chosen, and feces from 25 randomly selected pigs in each of them were individually collected. The same animals were later sampled (rectal swab, intestinal content and mesenteric lymph nodes) at the slaughterhouse. After the introduction of new animals into farm N1 and P1, other 25 pigs on each farm were examined as described above. In the preliminary screening, Salmonella was isolated from pen feces samples of 3 of the 10 investigated farms. Two of these herds showed a high level contamination. Eight Salmonella serotypes (Agona, Bredeney, Lexington, London, Mbandaka, Panama, Schwartzengrund, Salmonella sp) were found, with serotypes Agona and Bredeney being the most frequent. When individual animals were sampled, Salmonella was isolated in all selected farms. Salmonella was isolated in 6.4% of feces collected on the farm, 5.3% of intestinal contents and 5.6% of lymph nodes. Antibiogram testing of the isolated strains showed 97.8% resistance to sulphonamides, 82.6% to streptomycin, 36.9% to tetracyclin and 15.2% to sulfazotrim.

Molecular analysis of the iap gene of Listeria monocytogenes isolated from cheeses in Rio Grande do Sul, Brazil

The polymorphic region sequences in the iap gene were analyzed in 25 strains of Listeria monocytogenes isolated from cheeses in the state of Rio Grande do Sul, and compared with reference strains. This investigation distinguished two clusters of L. monocytogenes: I (20 strains) and II (5 strains).

Sorotipos de Salmonella isolados em uma propriedade de suínos de terminação no Sul do Brasil

Fifteen different serovars of Salmonella were isolated from a swine farm, two of the isolated serovars, Mbandaka and Tennessee, were also found in the feed supplied to the animals. This study demonstrated the diversity of serovars that could occur in a farm and the need of a better understanding on epidemiology of Salmonella infection.

Qualidade bacteriológica de queijos artesanais comercializados em estradas do litoral norte do Rio Grande do sul, Brasil

The consumption of homemade cheese, which is sold in little shops along the road, is very common in the state of Rio Grande do Sul, Brazil. Generally, these products are not manufactured according to the good hygiene guidelines; and may be a risk to the consumers’ health. The aim of this research was the assessment of the bacteriological quality of homemade cheese sold in the region along the northern coast of Rio Grande do Sul. Cheese samples were taken and total and faecal coliform counting per gram sample were established. The samples were also examined for the presence of Listeria spp. and Brucella spp. In total, 80 samples, from 29 commercial establishments were analysed, of which 62 of Colonial type; 10, of Provolone; 6 of Ricotta and 2, of Cacciocavallo type. At the moment of sampling, 71% of them were not stored under refrigeration conditions. In all the samples the presence of total coliform could be demonstrated and 62 of these were tested for the presence of faecal coliforms. In 84% of the samples more then 2.73 - 3.7log.UFC g - 1 (from 500 to 5000UFC mL -1 ) of faecal coliform could be demonstrated, with is considered the maximum limit still allowed to be present in cheese samples. Of the 29 establishments analysed, 27 had products with coliforms counts above these limits. Of the 80 samples, 16% had Listeria sp., of which 3.7% were identified as Listeria monocytogenes. A correlation was found between the season and the isolation of Listeria spp.: in the spring the highest number was detected. Brucella spp. could not be detected in the 80 samples analysed. The high frequency of faecal coliforms and the presence of L. monocytogenes revealed that the consumption of these homemade cheeses can become a risk of infection to the population, especially for immunocompromised persons.

Sanitary quality, occurrence and identification of Staphylococcus sp: in food services

Sanitary conditions are essential for the production of meals and control of the presence of pathogensis important to guarantee the health of customers. The aim of this study was to evaluate the sanitary quality of food services by checking the presence of thermotolerant coliforms, Staphylococcus sp. and evaluate the toxigenic potential from the latter. The analysis was performed on water, surfaces, equipment, ready-to-eat foods, hands and nasal cavity of handlers in seven food services. The water used in food services proved to be suitable for the production of meals. Most food, equipment and surfaces showed poor sanitary conditions due to the presence of thermotolerant coliforms (60.6%). Twenty-six Staphylococcus species were identified from the 121 Staphylococcus isolates tested. Staphylococci coagulase-negative species were predominant in the foods, equipment and surfaces. In food handlers and foods, the predominant species was Staphylococcus epidermidis. Twelve different genotypes were found after PCR for the classical enterotoxin genes. The seb gene (19.8%) was the most prevalent among all Staphylococcus sp. Both coagulase-positive and coagulase-negative Staphylococci showed some of the genes of the enterotoxins tested. We conclude that there are hygienic and sanitary deficiencies in the food services analyzed. Although coagulase-positive Staphylococci have not been present in foods there is a wide dispersion of enterotoxigenic coagulase-negative Staphylococci in the environment and in the foods analyzed, indicating a risk to consumer health.