Detección de bacillus cereus toxigénicos en productos lácteos con especias y leches deshidratadas colectadas en Costa Rica / Toxigenic bacillus cereus detection in lactic products with spices and dehydrated milk collected in Costa Rica

Bacillus cereus es un bacilo Gram-positivo de amplia distribución en la naturaleza y asociado a diversos tipos de alimentos que, bajo ciertas circunstancias causa patologías de diversa índole. Se han descrito cepas diarrogénicas y eméticas basándose en el tipo de toxinas producidas. Con el fin de determinar el riesgo de salud que representa en esta bacteria, se determinó el potencial toxigénico de cepas aisladas a partir de quesos maduros con especias, quesos crema con especias y leches deshidratadas expendidas en San José, Costa Rica, mediante un PCR múltiple con oligonucleótidos específicos para los genes codificantes de las toxinas HBL y Nhe. A partir de 45 muestras recolectadas, se obtuvieron 15 aislamientos de B. cereus, (60 por ciento provenientes de queso crema con especias, 7 por ciento de leche deshidratada y 13 por ciento de queso maduro con especias). Todas las cepas estudiadas presentaron al menos uno de los genes analizados, seis de ellas provenientes de leches deshidratadas y quesos crema, exhibieron evidencia molecular de los genes nheB, nheA, nheC, hblD, hblA y hblC lo cual permite confirmar la correlación descrita para la presencia de los operones codificantes para la HBL y la Nhe. No obstante, la no detección de un gen no puede considerarse como prueba definitiva de su ausencia dado que existen polimorfismos en las secuencias de los genes aquí analizados. Los resultados demuestran que múltiples cepas de B. cereus encontradas en lácteos comprados en Costa Rica contienen los genes necesarios para sintetizar toxinas, por lo tanto es importante el manejo adecuado de estos productos ya que eventualmente pueden representar un riesgo para la salud pública.

Bacillus cereus is a Gram positive rod widely distributed in nature and associated to different types of food that, under some circumstances, may cause pathology to human beings. Diarrheic and emetic strains have been described based on the type of toxins produced. In order to determine the risk to health represented by this bacteria, the toxigenic potential of strains isolated from cheese with spices, spread cheese with spices and dehydrated milk, all sold in San José, Costa Rica, were determined using a multiplex PCR technique with oligonucleotides specific for the genes coding toxins HBL and Nhe. From 45 samples collected, 15 isolates of B cereus were obtained (60 percent coming from spread cheese with spices 7 percent from dehydrated milk and 13 percent from cheese with spices). All the strains analyzed presented at least one of the genes analyzed; six of them, coming from dehydrated milk and spread cheese, showed molecular evidence of the genes nheB, nheA, nheC, hblD, hblA y hblC, confirming the correlation described for the presence of operons codifying for HBL and Nhe. Nevertheless, the no detection of a gene cannot be considered as a definitive proof of its absence, given the existence of polymorphism in the sequences of the genes analyzed. The results obtained show that multiple of the B cereus strains found in lactic products from Costa Rica have the necessary genes for synthesizing toxins, so the correct handling of these products is very important since they can represent a risk for public health.

[Toxigenic Bacillus cereus detection in lactic products with spices and dehydrated milk collected in Costa Rica]. / Detección de Bacillus cereus toxigénicos en productos láacteos con especias y leches deshidratadas colectadas en Costa Rica.

Bacillus cereus is a Gram positive rod widely distributed in nature and associated to different types of food that, under some circumstances, may cause pathology to human beings. Diarrheic and emetic strains have been described based on the type of toxins produced. In order to determine the risk to health represented by this bacteria, the toxigenic potential of strains isolated from cheese with spices, spread cheese with spices and dehydrated milk, all sold in San José, Costa Rica, were determined using a multiplex PCR technique with oligonucleotides specific for the genes coding toxins HBL and Nhe. From 45 samples collected, 15 isolates of B cereus were obtained (60% coming from spread cheese with spices 7% from dehydrated milk and 13% from cheese with spices). All the strains analyzed presented at least one of the genes analyzed; six of them, coming from dehydrated milk and spread cheese, showed molecular evidence of the genes nheB, nheA, nheC, hblD, hblA y hblC, confirming the correlation described for the presence of operons codifying for HBL and Nhe. Nevertheless, the no detection of a gene cannot be considered as a definitive proof of its absence, given the existence of polymorphism in the sequences of the genes analyzed. The results obtained show that multiple of the B cereus strains found in lactic products from Costa Rica have the necessary genes for synthesizing toxins, so the correct handling of these products is very important since they can represent a risk for public health.