RESUMO
The objectives of this study were: (1) to estimate STEC frequency in hide and carcass samples taken from beef slaughterhouses supplying the domestic market in Argentina, (2) to establish the pheno-genotypic characteristics of STEC and non-toxigenic Escherichia coli of serogroups O26, O45, O103, O121, O111, O145 or O157 isolated from the analyzed samples and, (3) to study their clonal relatedness. Sixty hides and 60 carcasses were analyzed. At the screening step, 48% of hide and 80% of carcass samples tested positive for the stx gene by endpoint PCR. The STEC isolation rate was 5% for hides and 8% for carcasses. The isolation rate of STEC-positive for O26, O45, O103, O111, O145 or O157 serogroups was 0% for hides and 2% for carcasses. With the purpose of studying the clonal relatedness of isolates, macrorestriction fragment analysis by pulsed-field gel electrophoresis was performed. The results indicated cross-contamination between hides and between carcasses of animals in the same lot and, that the origin of carcass contamination was their own hide, or the hides of other animals in the same lot. The high detection rate at the screening step, especially in carcasses, and the evidence of cross-contamination show the need to apply additional in-plant intervention strategies aimed at preventing carcass contamination.
Los objetivos del presente estudio fueron tres: 1) estimar la frecuencia de Escherichia coli productor de toxina Shiga (STEC) en muestras de cuero y carcasa de bovinos en frigoríficos de consumo interno de Argentina; 2) realizar la caracterización feno-genotípica de las cepas STEC y de Escherichia coli no toxigénicas pertenecientes a los serogrupos O26, O45, 0103, O121, O145 u O157 aisladas a partir de las muestras analizadas; 3) establecer la relación clonal de ese conjunto de cepas. Se analizaron 60 cueros y 60 carcasas. En la etapa de tamizaje, el gen stx se detectó en el 48% de las muestras de cuero y en el 80% de las muestras de carcasa por una PCR de punto final. La frecuencia de recuperación de cepas STEC fue del 5% en cueros y del 8% en carcasas, y la de cepas STEC positivas para los serogrupos O26, O45, O103, O121, O111, O145 u O157 fue del 0% en los cueros y del 2% en las carcasas. La relación clonal de las cepas aisladas se investigó a través de electroforesis de campo pulsado y análisis de los patrones de macrorrestricción generados. Los resultados demostraron la existencia de contaminación cruzada entre cueros y carcasas de animales pertenecientes a un mismo lote, y también que el origen de la contaminación fue el propio cuero del animal o el cuero de otros animales pertenecientes al mismo lote. Los altos porcentajes de detección en la etapa de tamizaje, especialmente en carcasas, y la evidencia de contaminación cruzada ponen de manifiesto la necesidad de evaluar la implementación de estrategias de intervención tendientes a evitar la contaminación de carcasas.
Assuntos
Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/virologia , Técnicas de Genotipagem/métodos , Carne Vermelha/microbiologia , Argentina , Programas de Rastreamento/veterinária , MatadourosRESUMO
The objectives of this study were: (1) to estimate STEC frequency in hide and carcass samples taken from beef slaughterhouses supplying the domestic market in Argentina, (2) to establish the pheno-genotypic characteristics of STEC and non-toxigenic Escherichia coli of serogroups O26, O45, O103, O121, O111, O145 or O157 isolated from the analyzed samples and, (3) to study their clonal relatedness. Sixty hides and 60 carcasses were analyzed. At the screening step, 48% of hide and 80% of carcass samples tested positive for the stx gene by endpoint PCR. The STEC isolation rate was 5% for hides and 8% for carcasses. The isolation rate of STEC-positive for O26, O45, O103, O111, O145 or O157 serogroups was 0% for hides and 2% for carcasses. With the purpose of studying the clonal relatedness of isolates, macrorestriction fragment analysis by pulsed-field gel electrophoresis was performed. The results indicated cross-contamination between hides and between carcasses of animals in the same lot and, that the origin of carcass contamination was their own hide, or the hides of other animals in the same lot. The high detection rate at the screening step, especially in carcasses, and the evidence of cross-contamination show the need to apply additional in-plant intervention strategies aimed at preventing carcass contamination.
Assuntos
Matadouros , Bovinos/microbiologia , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Argentina , GenótipoRESUMO
Shiga toxin-producing Escherichia coli strains are worldwide associated with sporadic human infections and outbreaks. In this work, we report the availability of high-quality draft whole-genome sequences for 19 O157:H7 strains isolated in Argentina.
RESUMO
We have reviewed the risk factors for the occurrence of Shiga toxin-producing Escherichia coli (STEC)-associated human diseases. The analysis of STEC surveillance data and trends shows differences in frequency and severity of the illnesses across countries, whereas the economic and social costs for the affected families, the community, and the health system are better estimated in developed countries. The occurrence of STEC infections is determined by the interaction of the pathogen, the reservoirs, and the biological, cultural, and behavioral aspects of the host. The main risk factors identified in earlier case-control and population-based studies were dietary behaviors and beef consumption. However, in recent years, other risky exposures have also emerged, like the consumption of raw vegetables and sprouts, working or camping in rural areas, visiting farms, and person-to-person transmission. Epidemiological changes have also been determined by the intensification of cattle production, the increase in centralized food production and distribution, and the growth in the volume of international trade of foods. The main lessons learned from recent large outbreaks are knowledge of virulence determinants of new pathogenic strains, recognition of new vehicles of infection, development of new methodologies for detecting STEC in foods and humans, improvement in food regulations and hygiene guidelines, new therapeutic approaches in the treatment of infected patients, establishment of continuous educational programs for food consumers, and enhanced cooperation and teamwork of regional and international networks.
Assuntos
Surtos de Doenças , Infecções por Escherichia coli/epidemiologia , Doenças Transmitidas por Alimentos/epidemiologia , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Bovinos , Saúde Global , Humanos , Fatores de RiscoRESUMO
Shiga toxin-producing Escherichia coli (STEC) cause nonbloody (NBD) and bloody diarrhea (BD), and hemolytic uremic syndrome (HUS). Cattle have been described as their main reservoir. STEC O157:H7 is recognized as the predominant serotype in clinical infections, but much less is known about the dominant subtypes in humans and animals or their genetic relatedness. The aims of this study were to compare the STEC O157 subtypes found in sporadic human infections with those in the bovine reservoir using stx-genotyping, phage typing, and XbaI-pulsed-field gel electrophoresis (PFGE), and correlate the subtypes with the severity of clinical manifestations. The 280 STEC O157:H7 strains collected included in this study were isolated from HUS (n=122), BD (n=69), and NBD (n=30) cases, and healthy carriers (n=5), and from bovines (n=54) in the abattoirs. The stx-genotyping showed that stx2/stx(2c(vh-a)) was predominant in human (76.1%) and in bovine strains (55.5%), whereas the second more important genotype was stx2 (20.8%) in human and stx(2c(vh-a)) (16.7%) in cattle strains. In human strains, PT4 (37.6%), PT49 (24.3%), and PT2 (18.6%) were the most frequent PTs (80.5%). In bovine isolates, PT2 (26%), PT39 (16.7%), and PT4 and PT49 (11.1% each) were predominant. By XbaI-PFGE, all 280 strains yielded 148 patterns with 75% similarity, and 169 strains were grouped in 37 clusters. Identical PT-PFGE-stx profile combinations were detected in strains of both origins: PT4-AREXH01.0011-stx2/stx(2c(vh-a)) (12 humans and one bovine), PT4-AREXH01.0543-stx2/stx(2c(vh-a)) (one human and four bovines), PT2-AREXH01.0076-stx2/stx(2c(vh-a)) (one human and four bovines), PT49-AREXH01.0175-stx2/stx(2c(vh-a)) (seven humans and one bovine), and PT49-AREXH01.0022-stx2/stx(2c(vh-a)) (seven humans and one bovine). No correlation was found among the stx-genotypes, the phage type, and the clinical symptoms.
Assuntos
Bovinos/microbiologia , Reservatórios de Doenças/microbiologia , Disenteria Bacilar/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli O157/isolamento & purificação , Síndrome Hemolítico-Urêmica/microbiologia , Matadouros , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Animais , Argentina/epidemiologia , Tipagem de Bacteriófagos , Portador Sadio/microbiologia , Disenteria Bacilar/epidemiologia , Disenteria Bacilar/fisiopatologia , Eletroforese em Gel de Campo Pulsado , Doenças Endêmicas , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/fisiopatologia , Escherichia coli O157/classificação , Escherichia coli O157/metabolismo , Hemorragia Gastrointestinal/etiologia , Técnicas de Genotipagem , Síndrome Hemolítico-Urêmica/epidemiologia , Síndrome Hemolítico-Urêmica/fisiopatologia , Humanos , Vigilância da População , Índice de Gravidade de Doença , Toxina Shiga II/genética , Toxina Shiga II/metabolismoRESUMO
Between July 1999 and December 2000, the prevalence of Shiga toxin-producing Escherichia coli (STEC) was established in 200 Argentine healthy young beef steers (14-16 months old) grown under local production systems with a feed grain period of 3-4 months, and the STEC strains isolated were examined in regard to their phenotypic and genotypic characteristics. Stool samples (n = 70) and rectal swabs (n = 130) were taken at the slaughterhouse level. By polymerase chain reaction (PCR), Shiga toxin (stx) gene sequences were detected in 69% of the samples. Eighty-six STEC strains were isolated from 39% of the animals. Serogroups identified, in order of frequency, were: O8 (16 strains), O113 (14), O103 (5), O91 (4), O171 (3), O174 (3), O25 (2), O112 (2), O145 (2), O2, O11, O104, O121, O128, O143, O146, O157. The most frequent serotype isolated was O8:H19 (12.9%). A total of 17 serotypes, including E. coli O157:H7 found in one animal (0.5%), have been previously associated with hemolytic uremic syndrome (HUS), bloody and non-bloody diarrhea in different countries, including Argentina. The prevalent genotype isolated was stx2 (51 of 86, 59.3%). Subtyping of stx2 variants showed the prevalence of stx2vh-b (25.6%) and stx2vh-a types (24.4%), and revealed the presence of an atypical stx2-v. Only 7.0% of STEC strains carried eae, and 33.7% harbored EHEC-hlyA gene. The full virulent genotype (stx/eae/EHEC-hlyA) was found to be present in 4 of the 86 (4.7%) STEC strains isolated. This research indicates that young steers from the main beef-producing area of Argentina are an important reservoir of STEC strains; however, its importance as agents of human diseases in our country has still to be established.
Assuntos
Doenças dos Bovinos/microbiologia , Reservatórios de Doenças/veterinária , Infecções por Escherichia coli/veterinária , Escherichia coli/patogenicidade , Toxina Shiga/biossíntese , Matadouros , Animais , Argentina/epidemiologia , Bovinos , Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Fezes/microbiologia , Masculino , Antígenos O/genética , Reação em Cadeia da Polimerase/métodos , Prevalência , Reto/microbiologia , Sorotipagem , Toxina Shiga/genética , VirulênciaRESUMO
The antibotulinal effect of sodium propionate was evaluated by a factorial-design experiment and by an inoculated-pack study on a shelf-stable beef product. Processing of samples involved curing, cooking, vacuum packing, and gamma irradiation. The factorial-design experiment involved 240 samples treated with 0, 0.8, 2.0, and 3.3% sodium propionate, challenged with 101 to 105 spores of type A Clostridium botulinum per package, irradiated with 2.5, 5, 7.5, and 10 kGy, and stored at 28°C for up to 4 months. In the pack study, 110 samples with 2% added sodium propionate were challenged with 108 spores of C. botulinum per package, irradiated with 12.5 kGy, and stored (28°C) for 8 months. Addition of 0.8% sodium propionate resulted in a delay (compared to control samples) in toxigenesis of 18 (5 kGy), 34 (2.5 kGy), and 34 (7.5 kGy) days, while no toxin was detected in samples irradiated with 10 kGy. Samples containing 2 and 3.3% sodium propionate were not toxic at any irradiation dose assayed. A safety level, expressed as the number of decimal reductions (DR = log 1/P) for the combination 0.8% sodium propionate and 10 kGy, was estimated to be >4.4. In the inoculated pack study, 2 of 107 samples became toxic, and the safety level treatment resulted in 10.7 DR. Sodium propionate in combination with other processing factors was very effective in preventing C. botulinum toxigenesis: it can be used as a further safety hurdle in the development of shelf-stable meat products.
RESUMO
Several thermal processes were tested to inactivate foot-and-mouth disease virus in beef miniburgers using a dry oven to grill and a steam oven to finish the cooking. A satisfactory product free of foot-and-mouth disease virus was obtained by grilling the contaminated miniburgers in the dry oven for 299 s at 208°C, followed by steam cooking in the moist oven for 190 s with a minimum average exit temperature of 99.4°C. It was found that a temperature indicator device is a reliable tool to verify the thermal process.
RESUMO
We determined the virucidal effectiveness against foot-and-mouth disease virus of the low-temperature long-time cooking of virus-contaminated semitendinosus muscle (ST). Of the 11 time and temperature combinations examined, over a range of 63°C to 75°C for extended periods, the respective processing conditions of 71°C for 10.66 h and 75°C for 5.75 h were virucidal. Samples cooked under these temperature-time combinations were more tender (P<0.01) and had better overall acceptability (P<0.05) than beef cuts cooked by conventional commercial processes currently used in Argentina for meat to be exported. Product yields were increased from 60% for the commercial process to 67.8% or 68.6%, respectively, for the two virucidal thermal processes.