RESUMO
A total of 118 Staphylococcus aureus strains isolated from routine sampling, samples from food poisoning outbreaks and human clinical specimens were examined for the production of enterotoxins A, B, C, D and E. The toxic properties of strains were compared with other biochemical characteristics and with the sensitivity to antibiotics. Of the total strains examined, 17.8% (21 strains) produced enterotoxins, and of the toxigenic strains, 81% (17 strains) produced just one type of enterotoxin and 19% (4 strains) two types. Enterotoxin A production was found in 52.4% strains, the other enterotoxins detected in decreasing order of frequency were: C; B; AD; D; AB and BD. All the strains examined produced catalases, coagulases, thermonuclease and fermented glucose; 81 and 89.7% for toxigenic and non-toxigenic strains, respectively, fermented mannitol; 47.6 and 54.6% hydrolyzed casein and 47.6 and 52.6% gelatin; 85.7 and 92.8% produced yellow or orange pigment. Mixed acid fermentation was carried out in 100% and in 96.9%; acetoin was produced by 57.1 and 47.4%; one or more hemolysins were released by 85.7 and 92.8% of the toxigenic and non-toxigenic strains, respectively. Sensitivity to antibiotics was widespread among all the strains. No relation was found between enterotoxin B production and methicillin and tetracycline resistance. Neither the biochemical properties nor the sensitivity to antibiotics has been shown to correlate reliably with toxin production.
Assuntos
Enterotoxinas/análise , Staphylococcus aureus/classificação , Antibacterianos/farmacologia , Microbiologia de Alimentos , Humanos , Testes de Sensibilidade Microbiana , Intoxicação Alimentar Estafilocócica/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/metabolismoRESUMO
A total of 118 Staphylococcus aureus strains isolated from routine sampling, samples from food poisoning outbreaks and human clinical specimens were examined for the production of enterotoxins A, B, C, D and E. The toxic properties of strains were compared with other biochemical characteristics and with the sensitivity to antibiotics. Of the total strains examined, 17.8
(21 strains) produced enterotoxins, and of the toxigenic strains, 81
(17 strains) produced just one type of enterotoxin and 19
(4 strains) two types. Enterotoxin A production was found in 52.4
strains, the other enterotoxins detected in decreasing order of frequency were: C; B; AD; D; AB and BD. All the strains examined produced catalases, coagulases, thermonuclease and fermented glucose; 81 and 89.7
for toxigenic and non-toxigenic strains, respectively, fermented mannitol; 47.6 and 54.6
hydrolyzed casein and 47.6 and 52.6
gelatin; 85.7 and 92.8
produced yellow or orange pigment. Mixed acid fermentation was carried out in 100
and in 96.9
; acetoin was produced by 57.1 and 47.4
; one or more hemolysins were released by 85.7 and 92.8
of the toxigenic and non-toxigenic strains, respectively. Sensitivity to antibiotics was widespread among all the strains. No relation was found between enterotoxin B production and methicillin and tetracycline resistance. Neither the biochemical properties nor the sensitivity to antibiotics has been shown to correlate reliably with toxin production.
RESUMO
Sixty seven samples of ice-creams were taken from seven different semi-industrial and small-scale shops. 43.3% of the samples were positive for the investigation of Staphylococcus aureus in 1 g; 88% showed less than 10 St. aureus in 1 g; 10.5% between 10 and 100 and 1.5% between 101 and 1,000. In 29 strains was investigated enterotoxigenicity, as well as the response to different biochemical tests and the susceptibility to antibiotics: 21% of the strains were toxigenic (4 produced enterotoxin A, 1 enterotoxin B and 1 enterotoxins A and D). There was no difference between the toxigenic and non-toxigenic strains when 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 susceptibility to different antibiotics. On the basis of the present study it is proposed to incorporate in article 1075 of the Argentine Food Code the limit of 100 Staphylococcus aureus in 1 g of ice creams.
Assuntos
Contaminação de Alimentos , Sorvetes/análise , Staphylococcus aureus/isolamento & purificação , Enterotoxinas/análise , Microbiologia de Alimentos , Indústria de Processamento de Alimentos , Testes de Sensibilidade Microbiana , Staphylococcus aureus/classificaçãoRESUMO
Sixty seven samples of ice-creams were taken from seven different semi-industrial and small-scale shops. 43.3
of the samples were positive for the investigation of Staphylococcus aureus in 1 g; 88
showed less than 10 St. aureus in 1 g; 10.5
between 10 and 100 and 1.5
between 101 and 1,000. In 29 strains was investigated enterotoxigenicity, as well as the response to different biochemical tests and the susceptibility to antibiotics: 21
of the strains were toxigenic (4 produced enterotoxin A, 1 enterotoxin B and 1 enterotoxins A and D). There was no difference between the toxigenic and non-toxigenic strains when 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 susceptibility to different antibiotics. On the basis of the present study it is proposed to incorporate in article 1075 of the Argentine Food Code the limit of 100 Staphylococcus aureus in 1 g of ice creams.
RESUMO
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
Assuntos
Leite , Microbiologia de Alimentos , Sorvetes , Staphylococcus aureusRESUMO
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
