Bioautography-guided isolation of antibacterial compounds of essential oils from Thai spices against histamine-producing bacteria

The outbreak of histamine fish poisoning has been being an issue in food safety and international trade. The growth of contaminated bacterial species including Morganella morganii which produce histidine decarboxylase causes histamine formation in fish during storage. Histamine, the main toxin, causes mild to severe allergic reaction. At present, there is no well-established solution for histamine fish poisoning. This study was performed to determine the antibacterial activity of essential oils from Thai spices against histamine-producing bacteria. Among the essential oils tested, clove, lemongrass and sweet basil oils were found to possess the antibacterial activity. Clove oil showed the strongest inhibitory activity against Morganella morganii, followed by lemongrass and sweet basil oils. The results indicated that clove, lemongrass and sweet basil oils could be useful for the control of histamine-producing bacteria. The attempt to identify the active components using preparative TLC and GC/MS found eugenol, citral and methyl chavicol as the active components of clove, lemongrass and sweet basil oils, respectively. The information from this study would be useful in the research and development for the control of histamine-producing bacteria in fish or seafood products to reduce the incidence of histamine fish poisoning

Estudio de la estabilidad microbiológica de la barracuda a través del tiempo de almacenaje en Costa Rica / Microbiological stability through storage period of Sphyraena ensis in Costa Rica

En el presente estudio se evaluaron algunos de los cambios microbiológicos y bioquímicos producidos en una especie de pez de consumo frecuente en Costa Rica, como lo es la barracuda Sphyraena ensis. Se evaluaron muestras de barracuda obtenidas durante la estación lluviosa y durante la estación seca. A cada una de éstas se le realizó un recuento aerobio psicrófilo, recuento e identificación de Vibrio, Enterococcus y Pseudomonas durante 6 días de almacenaje a dos temperaturas, 2 y 7ºC. Así también, se le realizó a cada una, la evaluación de la concentración de histamina producida mediante un inmunoensayo enzimático comercial. Los resultados obtenidos ponen de manifiesto que se da un incremento en los recuentos obtenidos a través del tiempo de almacenaje, dicho crecimiento es mayor al aumentar la temperatura de refrigeración. La mayoría de muestras mantenidas a 7ºC presentan recuentos superiores a 106 UFC/g luego de tres días de almacenaje, situación que no se presenta en las muestras mantenidas a 2ºC. No obstante, luego de 6 días de almacenaje, todas las muestras, independientemente de la temperatura de almacenaje, sobrepasan este valor. De la misma manera, se da un incremento en la concentración de histamina producida a través del tiempo de almacenaje, especialmente al conservar el producto a mayor temperatura debido al aumento de bacterias capaces de descarboxilar la histidina. No existe una diferencia estadísticamente significativa entre los recuentos obtenidos en estación lluviosa con respecto a la estación seca, no obstante, sí existe una diferencia con respecto a los géneros bacterianos aislados.

At the present study some of the microbiological and biochemical changes that occur through storage period in Sphyraena ensis, a fish specie of frequent consumption in Costa Rica were studied. Samples of S. ensis obtained during rainy and dry season were evaluated. Analysis included aerobic psychrotrophic count, identification and count of Vibrio, Enterococcus and Pseudomonas through a six day storage period at two different refrigeration temperatures, 2 and 7ºC. Same time, a commercial enzymatic immunoassay was used for the evaluation of the variation on the concentration of histamine produced in the different samples. Results obtained show that there is an increase on the bacteriological counts through the storage period, this increase is bigger as refrigeration temperature increases. Most of the samples maintained at 7ºC showed counts above 106 CFU/g after three days of storage, those stored at 2ºC did not present such high population levels. Nevertheless, after 6 days of storage, all samples, despite the storage temperature used, presented levels above the described one. Also, an histamine concentration increased through storage time, especially when the product was conserved at the higher temperature due to an increase in the number of histidine descarboxilating bacteria. There is no statistical difference between the counts obtained during rainy or dry season; nevertheless, there is a difference assicieated to the bacterial genera isolated.

Intoxicaçäo histamínica por pescado / Histamine paisoning from fish products

Discorre-se sobre as transformaçöes bioquímicas "post-mortem" no pescado e os mecanismos de formaçäo da histamina. Evidenciam-se as bactérias responsáveis pela produçäo dessa amina e os tipos de pescado envolvidos na intoxicaçäo por ela acarretada. Discutem-se os fatores condicionantes e os meios para prevenir a intoxicaçäo histamínica

Producción de aminas no volátiles por cepas de enterococos / Production of non-volatile amines by strains of enterococci

En años recientes ha surgido un marcado interés por los problemas relacionados con la presencia de aminas no volátiles en distintos tipos de quesos, en especial desde la puesta en evidencia de un "síndrome del queso". Dado que no ha sido aún totalmente aclarada la capacidad de los distintos grupos microbianos empleados en los procesos de caseificación para producir estas aminas, se estudió la capacidad de producción de tiramina, triptamina e histamina de cepas de enterococos de probable utilización para la elaboración de "startes". Se esayaron 41 epas de enterococos, cultivándolas en leche sola y en leche con el agregado de los aminoácidos precursores. La extracción y análisis cromatográfico para detectar la presencia de animas se llevaron a cabo según el método indicado por Colonna y col. Se determinó que sólo bajos porcentajes de cepas de Streptococcus faecalis subsp. liquefaciens y de Streptococcus durans (34 y 11%, respectivamente) produjeron trazas de tiramina y triptamina al desarrolar en leche sola. En cambio, cuando se cultivaron en presencia de los aminoácidos precursores, elevados porcentajes de cepas de todas las especies produjeron tiramina en altas concentraciones, y porcentajes variables de ellas produjeron triptamina en concentraciones no superiores a 200 ppm. Todas las cepas ensayadas resultaron incapaces de producir histamina, en las dos condiciones de cultivo estudiadas. Se puede concluir que existe una alta probabilidad de que los enterococos produzcan tiramina ...

The effect of immunotherapy on the in vitro productions of histamine, prostaglandin E2 and leukotriene C4 in asthmatic children.

In order to elucidate the working mechanisms of immunotherapy (IT), the in vitro productions of histamine, prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) were studied in 18 newly diagnosed and 20 hyposensitized (greater than 2 yr) asthmatic children. All were sensitive to house dust and dust mites. (D. pteronyssinus). Ten age-matched normal children were included as control. Polymorphonuclear (PMNs) and mononuclear (MNCs) leukocytes were separated by density gradient centrifugation and dextran sedimentation. PMNs (2 x 10(7) cells/ml) and MNCs (2 x 10(7) cells/ml) were stimulated with mite allergen (10 micrograms/ml) and calcium ionophore A23187 (1 microgram/ml) for 15 minutes. The plasma and culture supernatant (sup) histamine levels and sup PGE2 and LTC4 were measured by RIA. The results showed; 1) When compared to new patients, the treated patients had much lower plasma and sup histamine (p less than 0.001), no matter whether PMNs and MNCs were stimulated with allergen or A23187 and the normals had the lowest histamine level among 3 groups; 2) LTC4 in A23187-stimulated sup was lower in treated patients (p less than 0.05); 3) The PGE2 in allergen-stimulated sup was markedly increased in treated patients as compared to new patients (p less than 0.01) and the PGE2 in sup of normals was also much higher than that of new patients. Thus, immunotherapy is able to reverse the abnormal secretory pattern of inflammatory mediators of allergic patients, and this change may account, partly, for its clinical effectiveness.

Changes of allergen-specific antibodies, circulating immune complexes and restoration of polymorphonuclear leukocyte function after hyposensitization.

To explore the working mechanism(s) and the safety of long-term hyposensitization (HS) with house dust (HD), a series of studies were undertaken on 30 newly diagnosed and 30 hyposensitized asthmatic children. Twenty age- and sex-matched school children were included as control. The results showed: (1) HS was able to decrease the total serum IgE and increase the production of allergen-specific IgG blocking antibody, however, the allergen-specific IgE antibody remained nearly the same after HS for a couple of years, (2) Normal controls had allergen-specific IgG antibody but no IgE antibody, (3) Circulating immune complex concentration in the treated group did not differ significantly from the untreated group, (4) HS was able to suppress in vivo and in vitro histamine production and restore polymorphonuclear leukocyte (PMN) function in terms of Fc gamma R expression. These results suggest that HS is a specific and safe treatment, and provide solid rationale for its use in the treatment of respiratory allergic disease.