Cláudio Dias Timm

Subtilase Cytotoxin-Encoding subAB Operon Found Exclusively among Shiga Toxin-Producing Escherichia coli Strains

ABSTRACT The presence of subAB was investigated for 3,453 Escherichia coli strains of various pathogenic categories. The occurrence of other virulence genes in subAB-positive strains was investigated. The subAB operon was detected among some Shiga toxin-producing E. coli (STEC) serotypes devoid of eae and carrying ehxA. Most subAB-positive strains also harbored stx 2, iha, saa, and lpfA O113.

Plantas tóxicas para suínos

Poisonous plants for swine in Brazil, Uruguay and Argentina are reviewed. Poisoning by seeds of Senna occidentalis, as a cause segmentar muscle necrosis, and by seeds of Aeschynomene sp., as a cause of symmetric focal degeneration in the white matter of the cerebellum, are described. Nefrosis due to Amaranthus spp., soft tissue calcification caused by Solanum malacoxylon, acute periacinar liver necrosis caused by Wedelia glauca and Xanthium spp., and nervous, digestive and muscular signs caused by the fruits of Melia azedarach, are also mentioned. The intoxication by Crotalaria spectabilis, studied experimentally in Brazil as a cause of chronic hepatitis, is also reveiwed.

Campylobacter species isolated from poultry and humans, and their analysis using PFGE in southern Brazil.

Campylobacteriosis is a bacterial disease transmitted to humans through ingestion of contaminated food. Six hundred samples were collected, 200 from human stool samples, 200 from poultry products and 200 from poultry feces in Southern Brazil, and then inoculated on blood agar plates. A total of 58% of the poultry feces, 17% of the poultry meat, and 2% the of human stools tested positive for Campylobacter. Positive Campylobacter colonies were identified as Campylobacter jejuni or Campylobactercoli by multiplex PCR. Campylobacter isolates were analyzed using PFGE to compare different profiles according to the source. This study demonstrated that there are different Campylobacter clones distributed in different aviaries in Southern Brazil. In addition, PFGE molecular profiles suggested that broilers can be a source of contamination of poultry products. However, the human isolate studied did not show any relationship with other strains examined.

COMPOSIÇÃO DO LEITE COM INSTABILIDADE DA CASEÍNA 1

SUMMARY COMPOSITION OF MILK WHIT CASEIN INSTABILITY. In the present study, it was determined the composition of milk non-acid and non-mastitic with casein instability from dairy farms of Santa Vitoria do Palmar, Rio Grande do Sul, Brazil, between April 2002 and March 2003. The samples were subjected to titratable acidity, somatic cell count (SCC), to discard milk with casein instability due to acquired acidity or mastitis; alcohol test and fat, protein, lactose and total solids contents. The samples with positive alcohol tests, SCC lesser than 1.28x10 6 mL -1 and acidity lesser than 18oD were considered as milk with casein instability. The mean of fat content of instable milks (3.30%) was significantly higher than that of normal milk (3.04%). Lactose content was lower in instable milks (4.16%) than in normal milks (4.33%). Protein and total solids contents not showed significant difference between normal milk and instable milk. During autumn, the rates of fat content in milk with casein instability were higher than in the other seasons.

Avaliação de equipamento alternativo para pasteurização lenta de leite previamente envasado

A utilizacao de equipamentos alternativos de comprovada eficiencia pode colaborar na viabilizacao do uso da pasteurizacao lenta por pequenos produtores, melhorando a rentabilidade da atividade e diminuindo o comercio de leite informal. O presente trabalho teve por objetivo avaliar a eficiencia de equipamento alternativo para pasteurizacao lenta de leite previamente envasado. Quatorze partidas de 30 L de leite foram processadas e analisadas. As provas realizadas foram contagens de mesofilos aerobicos, coliformes totais e coliformes termotolerantes, calculo da reducao de mesofilos aerobicos e pesquisa da atividade das enzimas fosfatase e peroxidase. A eficiencia do processo de pasteurizacao em reduzir o numero de mesofilos aerobicos do leite variou de 99,97 a 99,99%. Todas as amostras de leite pasteurizado apresentaram contagens de coliformes totais e termotolerantes <0,3 NMP/mL e resultados negativos e positivos para fosfatase e peroxidase, respectivamente. O equipamento testado foi eficiente na pasteurizacao lenta do leite previamente envasado, pois, em todas as partidas analisadas, foi obtido leite pasteurizado dentro dos padroes estabelecidos pela legislacao brasileira para os parâmetros estudados.

Impacto da salmonelose na suinocultura e suas implicações em saúde pública

The objective of this study was to show the presence of Salmonella in the swine production chain, and its impact on public health. Bacteria of the Salmonella genus are an important cause of food transmitted diseases in Brazil. Around 10% of clinical salmonellosis cases are attributed to swine products. Humans can become infected through direct contact with the animals, both living and in slaughter houses; however, the most common cause of infection is the ingestion of contaminated food. Infection of swine herds can occur in any of the rearing stages, mainly through a fecal-oral cycle, where the bacteria will shelter in the lymph nodes and be excreted when the host is submitted to a stress factor, such as transport and/or regrouping. Equipment and utensils are also associated with cross contamination among animals, acting as vehicles in the propagation of the microorganism inside the industry or rearing facility. Furthermore, inadequate use of antimicrobial agents will contribute to the rise of resistant bacteria. This study shows that, in order to safeguard consumer health, awareness must begin in the rearing facilities, with special care to hygiene, biosafety, and the proper use of antibiotics. Further care must be considered during transportation, and especially rigorous measures should be set during slaughter.

Comportamento de Escherichia coli entero-hemorrágica, enteropatogênica e enteroinvasiva em ambrosia

Ambrosia is a type of Dulce de Leche hand-made with milk, eggs and sugar, widely consumed in South America, and it is commonly sold in street markets, supermarkets and candy shops. Food contamination by pathogenic micro-organisms usually occur during the processing steps, at the distribution centers, at the retail market or in the consumer home. This study aimed at evaluating the behavior of the pathogenic strains of Escherichia coli enterohemorrhagic (EHEC) ATCC 43895, enteropathogenic (EPEC) INCQS 00182 and enteroinvasive (EIEC) ATCC 43893 in ambrosia samples. Aliquots of ambrosia were experimentally contaminated by the strains analyzed in this study. Detections of the inoculated microorganisms were done at 0, 1, 2, 3, 4, 5, 10, 20 and 30 days of storage. EHEC was recovered from all of analyzed samples until five days after infection. EPEC survived in ambrosia and it was isolated until the fourth day of the experiment. EIEC strain remained viable during the 30 days of storage. The analyzed pathogenic strains of E. coli showed different behavior in ambrosia, but all of them demonstrated potential danger to the consumers health. This study works for warning to adopt appropriate hygiene and sanitary actions during the ambrosia production, packaging and manipulation.

Salmonella Typhimurium, Infantis, Derby, and Enteritidis survival in pasty dulce de leche

Dulce de leche is a food obtained by concentration and heating of milk with the addition of sucrose. The common practice of opening the dulce de leche containers in retail markets can lead to food contamination by Salmonella. The objective of this study was to evaluate the survivability of Salmonella enterica subsp. enterica serotypes Typhimurium, Enteritidis, Infantis and Derby in pasty dulce de leche. Aliquots of this sweet were experimentally contaminated with these microorganisms and later analyzed to evaluate microorganism viability after storage for 0, 1, 2, 3, 5, 10, and 20 days. Salmonella was recovered up to the 20 th day. These results are a warning about the need to adopt proper sanitary

Biofilm Formation by Coagulase-Positive Staphylococcus aureus Isolated from Mozzarella Cheese Elaborated with Buffalo Milk and its Effect on Sensitivity to Sanitizers

Background: The buffalo milk mozzarella cheese is a new product in the market, with high consumer acceptance and excellent prospects for trade. The cheese is rich in nutrients, which favors the proliferation of microorganisms that can cause food-borne diseases in the consumer. Staphylococcus aureus can cause gastro-enteritis in humans by the production of enterotoxins in food. One problem that may hinder the elimination of undesirable microorganisms in the food industry is the formation of biofilms. The objective of this study was to determine the effect of biofilm formation by Staphylococcus aureus isolated from buffalo mozzarella cheese on sensitivity to sanitizers. Materials, Methods & Results: Fifty samples of buffalo mozzarella cheese were analyzed to investigate the presence of S. aureus. The isolates were obtained through microbiological analysis and identified by PCR. The similarity of the strains was compared through rep-PCR. The distinct strains were tested for biofilm formation in microtiter plates. Soy Tripticase Broth (TSB) was placed in each well of the microtiter plate and overnight cultures of each strain was added. Wells without bacterial culture were used as controls. A villous cap was then placed on the plate and incubated for 48 h at 37°C. During incubation, the biofilms formed on the surface of the villi of the caps. For quantification of biofilm formation, material that remained attached to the cap was stained with crystal violet, the stained biofilm was extracted and the OD570 of each well was measured. Each strain was classified as non-biofilm forming, weak forming, moderately formed or formative strong. Strong forming and non-biofilm forming strains were tested on high density polyethylene, stainless steel and glass surfaces. Plates of 4 cm² of the different materials were placed in TSB where the culture of each isolate was inoculated separately. At each 48 h incubation the plates were washed to remove unbound cells and re-inserted into TSB without the inoculum. After five replicates of the procedure, sterile swabs were passed over the entire surface of each plate for counting in Baird-Parker agar. They were also tested for sensitivity to sodium hypochlorite and iodine after biofilm formation. The biofilm plates were immersed in flasks containing sanitizers, where they remained for 10 min. At the established contact time, the plates were immersed in neutralizing solution for 30 s. After washing with PBS, a sterile swab was passed on the surface of each plate and counts on Baird-Parker agar were performed. The bands profiles obtained on rep-PCR were identical when compared to isolates from the same sample, indicating that each sample was contaminated with only one S. aureus strain. From the twenty S. aureus strain identified, two isolates were classified as strong biofilm formers, seven as moderate formers, ten weak formers and one as non-biofilm builder. The two strong forming strains produced biofilm on the three surfaces tested. The application of sodium hypochlorite and iodine sanitizers promoted a reduction of approximately 2 log bacterial populations on all surfaces of both the biofilm and non-forming strains. Discussion: Most strains of S. aureus isolated from buffalo milk mozzarella cheese have the ability to form biofilm on the surfaces of equipment and utensils that have stainless steel, glass or high density polyethylene components. Although biofilm forming strains are no longer resistant to sanitizers sodium hypochlorite and iodine than non-forming sanitizers, they reach higher concentrations in the biofilm, resulting in larger bacterial populations remaining after application of the sanitizers. These results support the recommendation that the good hygienic practices adopted by industries processing buffalo milk mozzarella cheese should include specific measures to control the Staphylococcus aureus contamination.

Holding Pens as Sources of Contamination of Coagulase-Positive Staphylococcus to Pigs Waiting for Slaughter

Background: Coagulase-Positive Staphylococcus (SCP) are important pathogens related to foodborne illness associated with pork consumption. The isolation of SCP from pork products has been reported in several countries, including Brazil. Therefore, the identification of the sources of contamination of the pork products is fundamental to ensure the food safety. Although the animals remain in the holding pens during the pre-slaughter, these facilities have not been studied as a possible source of contamination for pigs. The aim of this study was to determine the importance of holding pens as sources of contamination of SCP to pigs and to identify other sources in the slaughter flowchart. Materials, Methods & Results: It was followed four pigs from ten different lots sent to slaughter. Prior to slaughter, samples were collected from the floors of the holding pens in the slaughterhouse. During slaughter, samples from seven different points were collected: 1) stool from the rectum immediately after stunning; 2) external surface of the carcass after dehairing; 3) internal surface of the carcass after evisceration; 4) external surface of the half-carcass prior to entry into the cold chamber; 5) tongue surface; 6) jowls; and 7) mesenteric lymph nodes. The strains were obtained through microbiological analysis. To compare the similarity between the strains, rep-PCR was performed. Of the ten samples collected in the holding pens, four (40%) were contaminated with SCP. At slaughter, 280 samples were collected and 56 (20%) SCP isolates were obtained. The lymph nodes were the point of greatest isolation (19.6%), followed by the surface of the carcass at the entrance to the cold chamber (17.8%), the rectum after desensitization (16.1%), carcass surface after opening of the abdominal cavity (16.1%), jowls (12.5%), carcass surface after dehairing (8.9%) and tongue surface (8.9%). In the rep-PCR analysis, isolates with indistinguishable band pattern were observed involving both those obtained on the holding pens and at different points in the slaughtering flowchart. Discussion: The holding pens contamination may have occurred due to hygiene failure after leaving lots with pigs harboring SCP. Considering that the recommendation, in view of animal welfare, is to use anti-slip material in the pens floor, it may be difficult to clean this area due to roughness in the concrete, which would allow the microorganisms remain in the place. Some studies have reported the presence of S. aureus in pigs from finishing farms, demonstrating that these animals may be harboring this bacterium in the gastrointestinal tract when sent to slaughter, excreting it in the pens during waiting in the slaughterhouse. Some strains isolated from tongue, rectum and lymph nodes were considered indistinguishable by rep-PCR from the strains isolated from the holding dump, what demonstrate that the holding pens act as an important source of SCP contamination for the pigs that will be slaughtered. The results show that the period in which the animals remain in the holding pens during pre-slaughter is sufficient for the pigs to be contaminated with SCP, the microorganisms to settle in the mesenteric lymph nodes and the animals excrete these bacteria in the feces. The persistence of the contamination to the end products is a possibility, since strains isolated from stool samples were also isolated from other points in the slaughter flowchart, including the carcass. It can be concluded that the holding pens are important sources of SCP contamination for the swine, which once contaminated, can disseminate the microorganism in the slaughter flowchart through the feces, mesenteric lymph nodes and oral cavity. This is the first study in Brazil that shows that the holding pens are important sources of SCP contamination for pigs sent to slaughter.