Preparación de reactivos para la detección de proteínas de diferentes especies animales por inmunodifusión / [Preparation of reactants for the detection of proteins from different animal species by immunodiffusion]

Qualitative identification of fresh ground meat samples of beef, sheep, pork, horse and rabbit has been made by the double agar gel diffusion test (method of Ouchterlony) and by immunoelectrophoresis. The reagents used were: 1) Antigens: saline meat extracts from different animal species, saline meat mixture extracts and whole sera from the different animal species. Meat extracts and sera were controlled by electrophoresis and the amounts of protein were estimated by the method of Lowry; 2) Antibodies: multivalent antisera anti-bovine, anti-ovine, anti-porcine and anti-equine, were obtained by immunization of rabbits with an emulsion of 1 vol of whole serum and 1 vol of Freund complete adjuvant; anti-rabbit serum was obtained by immunization of rats; antisera were controlled by the double agar gel diffusion test and by immunoelectrophoresis. To remove cross-reacting antibodies, when it was necessary, antisera were adsorbed.

Helados de elaboración industrial. Incidencia de Staphylococcus aureus y enterotoxigenicidad / [Ice cream of industrial manufacture. Incidence of Staphylococcus aureus and enterotoxigenicity]

A total of 70 samples of ice-creams, milk, milk cream and water or fruit based were obtained from 7 different industrial producers. Of these samples, 14.3

were positive for Staphylococcus aureus in 1 g: 97.2

showed less than 10 St. aureus in 1 g, 1.4

between 101-1,000 and 1.4

between 1,001-10,000. In 21 strains enterotoxigenicity, was investigated, as well as the response to different biochemical tests and the susceptibility to antibiotics: 9.5

of the strains were toxigenic (2 strains), 1 produced enterotoxin A and 1 enterotoxin B. There was no difference between toxigenic and nontoxigenic strains when the biochemical tests were performed (catalase test, coagulase test, thermostable nuclease production, anaerobic utilization of glucose and mannitol, gelatin and casein hydrolysis, production of hemolysins and pigments). All the strains showed a wide susceptibility when they were tested with different antibiotics. Our results confirm the limit introduced to the article 1078 of the Argentine Food Code for ice-creams of industrial production (100 per g) but there is no specification of the count method to be used.

Helados de elaboracion artesanal y semiindustrial. Incidencia de Staphylococcus aureus y enterotoxigenicidad. / Craft or semi-industrial ice cream. Occurence of Staphylococous aureus and enterogenicity

En 7 heladerias de elaboracion artesanal y semiindustrial se retiraron 67 muestras de helados a base de crema de leche y de agua. El 43,3% de las muestras fueron positivas para la investigacion de Staphylococcus aureus en 1 g, el 88% de las mismas presentaron menos de 10 St. aureus por g, 10,5% entre 10 y 100 y 1,5% entre 101 y 1.000.A 29 cepas se les determino la enterotoxigenicidad, la respuesta a diversas pruebas bioquimicas y la sensibilidad a antibioticos. El 21% de las cepas resultaron enterotoxigenicas (4 produjeron toxina A, 1 toxina B y 1 toxinas A y D). No se hallo diferencia en las pruebas bioquimicas realizadas (produccion de catalasa, coagulasas, termonucleasas, fermentacion de glucosa y manitol, hidrolisis de gelatina y caseina, produccion de pigmentos y hemolisinas) entre las cepas toxigenicas y no toxigenicas. Todas las cepas presentaron una amplia sensibilidad frente a los antibioticos. Como resultado del presente estudio se propone incorporar al articulo 1075 del Codigo Alimentario Argentino el limite de 100 Staphylococcus aureus por g en helados a base de crema y de agua

Taxonomia numerica de bacilos gram positivos anaerobios. / Numerical taxonomy of gram-positive anaerobic bacilli

Se estudiaron por taxonomia numerica 21 cepas de bacilos anaerobios Gram positivos empleandose ochenta caracteres morfologicos y bioquimicos. Se aplicaron dos metodos de codificacion (pesado y no pesado) y cuatro de agrupamiento (metodo de los pares no pesados usando promedios aritmeticos, metodo de ligamiento simple y metodo de ligamiento completo). Se obtuvieron ocho dendrogramas que muestran que Clostridium haemolyticum (cepas 1, 2, 4 y 7), C. subterminale (cepas 8 y 19), C. botulinum (cepa 14) y C. sporogenes (cepas 15) forman un grupo diferenciable de las restantes cepas. Outro grupo estaria constituido por C. perfringens (cepas 3, 5, 6, 12, 16 y 21) y C. paraperfringens (cepas 9, 10 y 11). De las cuatro cepas restantes la dos correspondientes a Propionibacterium acnes (cepas 17 y 18) guardan entre si una estrecha similitud. C. histolyticum (cepa 20) se une luego a un nivel muy inferior, mientras que C. butyricum (cepa 13) muestra un comportamiento variable. El ordenamiento obtenido es concordante con el dado por la taxonomia clasica