RESUMO
Mercury (Hg) is a highly toxic pollutant that poses in risk several marine animals, including green turtles (Chelonia mydas). Green turtles are globally endangered sea turtle species that occurs in Brazilian coastal waters as a number of life stage classes (i.e., foraging juveniles and nesting adults). We assessed total Hg concentrations and isotopic signatures ((13)C and (15)N) in muscle, kidney, liver and scute of juvenile green turtles and their food items from two foraging grounds with different urban and industrial development. We found similar food preferences in specimens from both areas but variable Hg levels in tissues reflecting the influence of local Hg backgrounds in food items. Some juvenile green turtles from the highly industrialized foraging ground presented liver Hg levels among the highest ever reported for this species. Our results suggest that juvenile foraging green turtles are exposed to Hg burdens from locally anthropogenic activities in coastal areas.
Assuntos
Monitoramento Ambiental/métodos , Preferências Alimentares , Mercúrio/análise , Tartarugas/metabolismo , Poluentes Químicos da Água/análise , Animais , Brasil , Isótopos de Carbono/análise , Rim/química , Fígado/química , Mercúrio/farmacocinética , Isótopos de Nitrogênio/análise , Distribuição Tecidual , Tartarugas/crescimento & desenvolvimento , Poluentes Químicos da Água/farmacocinéticaRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: Huperzia saururus (Lam.) Trevis. has an extensive ethnopharmacological use, mainly because of its aphrodisiac properties. The species is consumed as decoctions or infusions in traditional medicine. The purpose of the present research was to determine if Huperzia saururus is able to increase sexual potency by evaluating the ejaculatory response, in the presence of a decoction in spinal cord transected male rats. MATERIALS AND METHODS: The fictive ejaculation model to record the rhythmic contractions of the bulbospongiosus muscles that accompany ejaculation as an indicator of ejaculation occurrence was used. Sexually experienced male Wistar rats were used. The activation of the fictive ejaculation by the i.v. administration of a decoction was tested, as well as the effects of the oxytocinergic, cholinergic, adrenergic and nitrergic antagonism upon the pro-ejaculatory activity of Huperzia saururus. RESULTS: Decoction (3µg/animal) was able to activate the fictive ejaculation in spinal male rats, producing a statistically significant diminution on the latency of discharge parameter and a statistically significant augment for the number of discharges. Moreover, when sequential treatments using antagonists plus decoction were administered, the effects produced showed that prazosin prevent the pro-ejaculatory effect of the decoction and that the four antagonists assayed blocked the facilitatory effect of Huperzia saururus since the facilitation in the latency of response was prevented, and the number of discharges was reduced. Together these findings support the notion that the decoction exerts an aphrodisiac effect influencing the ejaculatory potency which is partially mediated by oxytocinergic, cholinergic, adrenergic and nitrergic spinal mechanisms. CONCLUSION: In agreement to the ethnopharmacological uses, Huperzia saururus decoction has aphrodisiac properties by influence on the ejaculatory potency.
Assuntos
Afrodisíacos/farmacologia , Ejaculação/efeitos dos fármacos , Huperzia/química , Extratos Vegetais/farmacologia , Animais , Masculino , Medicina Tradicional , Ratos , Ratos Wistar , Traumatismos da Medula Espinal/patologiaRESUMO
A collection of fishes from the Brazilian continental slope between 11 degrees and 23 degrees S obtained through trawling revealed nine species of Ipnopidae. Bathypterois bigelowi and Bathytyphlops marionae represent first records from the south-western Atlantic Ocean and Bathypterois grallator is reported off Brazil for the first time. Four species have their distribution extended in Brazilian waters: Bathypterois phenax, Bathypterois quadrifilis, Bathypterois viridensis and Ipnops murrayi. An identification key of Ipnopidae species from the south-western Atlantic Ocean is included.
Assuntos
Peixes/classificação , Animais , Oceano Atlântico , Brasil , Peixes/anatomia & histologiaRESUMO
Thirty-five strains of Bordetella bronchiseptica, recovered primarily from pigs, rabbits, dogs, cats and humans, were characterized by phenotypic and genotypic markers. Biochemical typing only showed variation in the ability to reduce nitrate to nitrite. OMP profiles from virulent strains showed variations in the region of 85-95kDa, which lead us to describe five OMP-types alpha, beta, gamma, delta and epsilon. Genotypic markers included the presence of IS1001, and polymorphisms in the flagellin gene (flaA) and pertussis toxin (PT) promoter region. The IS1001 was detected in 16 isolates (2 from humans and 10 from pigs) but was absent in rabbit isolates. The restriction profiles of the flaA gene allowed us to differentiate the strains into types A-C. The PT types were characterized by an RFLP assay and could be typed through patterns III-V. There was no apparent association between the flaA or PT types and the origin of the isolates. Eleven groups of isolates were identified on the basis of specific combinations of the analyzed markers. The combination of phenotypic and genotypic tests used could be useful in characterizing isolates and differentiating between certain clonal types of B. bronchiseptica.
Assuntos
Técnicas de Tipagem Bacteriana/veterinária , Bordetella bronchiseptica/classificação , Bordetella bronchiseptica/genética , Variação Genética , Polimorfismo de Fragmento de Restrição , Animais , Proteínas da Membrana Bacteriana Externa , Western Blotting/veterinária , Bordetella bronchiseptica/patogenicidade , Gatos , Cães , Eletroforese em Gel de Poliacrilamida/veterinária , Flagelina/genética , Genótipo , Humanos , Peso Molecular , Nitratos/metabolismo , Toxina Pertussis/genética , Fenótipo , Filogenia , Reação em Cadeia da Polimerase/métodos , Reação em Cadeia da Polimerase/veterinária , Coelhos , Especificidade da Espécie , SuínosRESUMO
In the present study biochemical tests and outer membrane protein profile (OMP) capacity for typing Bordetella bronchiseptica field isolates were evaluated. The biochemical tests were performed by API 20NE system. OMP enriched fractions were obtained from cultures under virulent and modulated conditions and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We have identified five patterns by differences in the bands in the 85-95 kDa region (alpha, beta, gamma, delta and epsilon) from virulent cultures; and three different patterns by the flagellin expressed isotype from modulated cultures (A: 40 kDa, B: 45 kDa, and C: 40 and 45 kD simultaneously). Isotypes alpha, beta and gamma were linked to isotpye A, isotype delta to B and C, and isotypes epsilon to B. There is no evident correlation between characterized isotypes and the origin of the isolate. Nitrate reduction was the unique variable biochemical characteristic, only observed in rabbit isolates. It was possible to differentiate seven groups with the traits included in the study. The capacity of discrimination of the traits analyzed using the Hunter and Gaston index was 0.829.
Assuntos
Técnicas de Tipagem Bacteriana , Bordetella bronchiseptica/classificação , Animais , Proteínas da Membrana Bacteriana Externa/análise , Bordetella bronchiseptica/genética , Bordetella bronchiseptica/patogenicidade , Eletroforese em Gel de Poliacrilamida , Flagelina/análise , Fenótipo , Coelhos , VirulênciaRESUMO
In the present study biochemical tests and outer membrane protein profile (OMP) capacity for typing Bordetella bronchiseptica field isolates were evaluated. The biochemical tests were performed by API 20NE system. OMP enriched fractions were obtained from cultures under virulent and modulated conditions and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We have identified five patterns by differences in the bands in the 85-95 kDa region (alpha, beta, gamma, delta and epsilon) from virulent cultures; and three different patterns by the flagellin expressed isotype from modulated cultures (A: 40 kDa, B: 45 kDa, and C: 40 and 45 kD simultaneously). Isotypes alpha, beta and gamma were linked to isotpye A, isotype delta to B and C, and isotypes epsilon to B. There is no evident correlation between characterized isotypes and the origin of the isolate. Nitrate reduction was the unique variable biochemical characteristic, only observed in rabbit isolates. It was possible to differentiate seven groups with the traits included in the study. The capacity of discrimination of the traits analyzed using the Hunter and Gaston index was 0.829.
RESUMO
In the present study biochemical tests and outer membrane protein profile (OMP) capacity for typing Bordetella bronchiseptica field isolates were evaluated. The biochemical tests were performed by API 20NE system. OMP enriched fractions were obtained from cultures under virulent and modulated conditions and were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). We have identified five patterns by differences in the bands in the 85-95 kDa region (alpha, beta, gamma, delta and epsilon) from virulent cultures; and three different patterns by the flagellin expressed isotype from modulated cultures (A: 40 kDa, B: 45 kDa, and C: 40 and 45 kD simultaneously). Isotypes alpha, beta and gamma were linked to isotpye A, isotype delta to B and C, and isotypes epsilon to B. There is no evident correlation between characterized isotypes and the origin of the isolate. Nitrate reduction was the unique variable biochemical characteristic, only observed in rabbit isolates. It was possible to differentiate seven groups with the traits included in the study. The capacity of discrimination of the traits analyzed using the Hunter and Gaston index was 0.829.
RESUMO
Odontogenic cysts (OC) are one of the main causes of jaw destruction. Information about these lesions in the Mexican population is scant. And for this reason the purpose of this work is to describe the frequency of the different varieties of OC recorded in two oral pathology services in Mexico City. As well as to compare the findings with those previously reported in other studies and to analyze the association of these lesions with the gender of the affected patients and the type of oral pathology service. There were a total of 856 OC; of these, 449 (52.5%) occurred in men, 403 in women (47%), and in 4 cases (0.5%) gender was not stated. There were 8 out of the 10 different types of OC recognized by the WHO. The most frequently diagnosed OC were radicular cyst (342 cases), dentigerous cyst (283 cases) and odontogenic keratocyst (184 cases). Together, these three entities represented 94.5% of all OC. Both the gender and the type of oral pathology service showed a significant association with radicular and dentigerous cysts (p<0.01). The knowledge of the origin, clinico-pathological features and the biological behavior of these lesions are basic aspects to achieve an early diagnosis and a proper treatment.
Assuntos
Doenças Mandibulares/epidemiologia , Doenças Maxilares/epidemiologia , Cistos Odontogênicos/epidemiologia , Feminino , Humanos , Masculino , Doenças Mandibulares/patologia , Doenças Maxilares/patologia , Cistos Odontogênicos/patologiaRESUMO
AIMS: The present study shows that Congo red binding and urease activity assays are useful for selection of virulent (Bvg+) Bordetella bronchiseptica cultures. METHODS AND RESULTS: Congo red binding and urease activity of Bvg+ B. bronchiseptica cultures in different liquid media were compared with the expression of virulence markers such as filamentous haemagglutinin and some outer membrane proteins (OMP). The correlation with the reference virulence markers allowed the establishment of cut-off values for the proposed markers to assure the virulent phenotype (> or = 26 nmol ml-1 of CR and < or = 2.6 U). Using both assays, modulated cultures with avirulent phenotype (Stainer-Scholte broth, with MgSO4 20 mmol l-1 and brain heart infusion broth) and semi-modulated cultures with intermediate phenotypes (tryptose phosphate broth and 83% Stainer-Scholte with MgSO4 5 mmol l-1 cultures) could be distinguished. CONCLUSION: CR binding assay and urease activity are specific and sensitive enough to detect intermediate phenotypes that could only be detected by subtle changes in OMP profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: The production of effective veterinary vaccines is hampered by reversible B. bronchiseptica antigenic modulation. The proposed assays are technically suitable for selection of virulent cultures to optimize vaccine production.
Assuntos
Bordetella bronchiseptica/metabolismo , Bordetella bronchiseptica/patogenicidade , Vermelho Congo/metabolismo , Urease/metabolismo , Proteínas da Membrana Bacteriana Externa/análise , Vacinas Bacterianas/microbiologia , Bordetella bronchiseptica/classificação , Bordetella bronchiseptica/enzimologia , Permeabilidade da Membrana Celular , Testes de Hemaglutinação , Fenótipo , VirulênciaRESUMO
The purpose of this study was to compare the natural fluorescence in the Harderian glands of the Syrian hamster, rat, mouse, Mongolian gerbil and guinea pig (both sexes). For each species, 10 animals (five males and five females) were used. Histological autofluorescence studies were performed using a fluorescence microscope (450-490 nm filter). Two different types of fluorescent cells were observed in both hamster (type AFI high intensity and type AFII, low fluorescence) and rat (type AFI, low fluorescence and type AFII, high fluorescence) Harderian glands. The fluorescence was basally located in all mice cells, whereas it was observed near the epithelial cell nuclei in the Mongolian gerbil (occupying two-thirds and one-third of the cells in males and females, respectively). A high intensity of fluorescence was present throughout the acinar cells in the guinea pig. The patterns of fluorescence identified exhibited a sexual dimorphism in all species studied. These results demonstrate that the Harderian glands of the animal species examined exhibit a variety of histological autofluorescence patterns.
Assuntos
Gerbillinae/anatomia & histologia , Cobaias/anatomia & histologia , Glândula de Harder/anatomia & histologia , Mesocricetus/anatomia & histologia , Camundongos Endogâmicos BALB C/anatomia & histologia , Ratos Wistar/anatomia & histologia , Animais , Cricetinae , Feminino , Fluorescência , Glândula de Harder/citologia , Glândula de Harder/ultraestrutura , Masculino , Camundongos , Microscopia de Fluorescência , RatosAssuntos
Diarreia/imunologia , Infecções por Rotavirus/imunologia , Rotavirus/imunologia , Animais , Anticorpos Antivirais/imunologia , Linfócitos B/imunologia , Capsídeo/imunologia , Diarreia/virologia , Modelos Animais de Doenças , Imunidade Ativa , Imunidade Inata , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos SCID , Infecções por Rotavirus/prevenção & controle , Infecções por Rotavirus/virologia , Linfócitos T/imunologia , Vacinas Virais/imunologiaRESUMO
Melatonin is a free radical scavenger and antioxidant. This indol is reported to efficiently scavenge both hydroxyl and peroxyl radicals and it also reduces both in vitro and in vivo tissue damage due to oxidants which generate oxygen toxic radicals. Lipopolysaccharide (LPS) administration induces oxidative damage in various tissues mainly due to its ability to increase reactive oxygen species. In the present work, we studied the morphological changes and lipid peroxidation in the Harderian gland after LPS administration and the effects of melatonin in preventing the induced changes. Hyperchromasia, vesicular degeneration, necrosis and infiltration with macrophages, monocytes and neutrophils were observed in the LPS-treated group (10 mg/kg, intraperitonally [i.p.]). Also, a typical structure of the glandular acini of the gland exhibited diffuse damage. In the LPS rats treated with melatonin (10 mg/kg, i.p.), a diminished number of infiltrative cells was seen, and cloudy swelling was reduced, as was nuclear hyperchromasia. Neither necrosis nor vesicular degeneration were noted in the melatonin-treated rats, and in general, glandular structure was preserved. Lipid peroxidation products increased significantly within six hours after LPS administration, and melatonin treatment decreased the LPS-dependent lipid peroxidation products. These data together suggest that melatonin protects the Harderian gland against LPS toxicity in terms of morphological damage.
Assuntos
Glândula de Harder/efeitos dos fármacos , Lipopolissacarídeos/toxicidade , Melatonina/farmacologia , Animais , Glândula de Harder/metabolismo , Glândula de Harder/patologia , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Bordetella pertussis virulence-associated 30-, 32-, 90- and 95-kDa outer membrane proteins were purified and their N-terminal amino acid sequences were determined. The 30- and 32-kDa outer membrane proteins showed identity to the C-terminal region of the precursors of the serum resistance protein (BrkA) and the tracheal colonization factor, respectively. We confirmed the cleavage site of these precursors after N731 for BrkA and after N393 for tracheal colonization factor. Associated with the 32-kDa outer membrane protein, we found a new group of 36-kDa virulence-associated peptides. The 95-kDa outer membrane protein showed identity to Vag8. The 90-kDa outer membrane protein did not show homology with the described proteins. We report the N-termini sequence of Vir-90, a novel potential virulence factor.
Assuntos
Proteínas da Membrana Bacteriana Externa/química , Bordetella pertussis/química , Bordetella pertussis/patogenicidade , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/isolamento & purificação , Eletroforese em Gel de Poliacrilamida/métodos , Humanos , Dados de Sequência Molecular , Precursores de Proteínas/química , Alinhamento de Sequência , VirulênciaRESUMO
Enteroinvasive Escherichia coli (EIEC) share important features with Shigella spp., but EIEC strains are difficult to identify because their biochemical reactions are variable, and Sereny tests or other biological and molecular assays are expensive or hard to perform. The aim of this work was to detect probable enteroinvasive E. coli strains by using four biochemical tests, in children under 5 years of age with and without acute diarrhea. 330 strains of E. coli isolated from children with diarrhea, and 660 strains from children without diarrhea were studied. All strains were tested with the following tests: mucus , lysine and ornithine decarboxylase and motility. The strains which were negative to the four tests were tested by Sereny assay. Twelve strains (3.6%) isolated from children with diarrhea were negative to the tests proposed; eleven were lactose positive and only one was lactose negative. Three strains (0.5%) from children without diarrhea were negative to the tests proposed and were lactose positive. All the 15 strains (100%) were positive in Sereny assay. We recommend the use of these four biochemical tests for initial detection of EIEC strains, because their cost is very low and it is feasible carry out them in small diagnostic laboratories.
Assuntos
Cápsulas Bacterianas/análise , Proteínas de Bactérias/análise , Técnicas Bacteriológicas , Carboxiliases/análise , Diarreia/microbiologia , Disenteria/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Pré-Escolar , Diarreia Infantil/microbiologia , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Escherichia coli/fisiologia , Estudos de Avaliação como Assunto , Estudos de Viabilidade , Fermentação , Humanos , Lactente , Lactose/metabolismo , Ornitina Descarboxilase/análise , VirulênciaAssuntos
Broncoscopia , Equinococose Pulmonar/diagnóstico , Idoso , Animais , Diagnóstico Diferencial , Equinococose Pulmonar/diagnóstico por imagem , Equinococose Pulmonar/transmissão , Exposição Ambiental , Feminino , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Ovinos/parasitologia , Tomografia Computadorizada por Raios X , Tuberculose/diagnóstico por imagemRESUMO
Neonatal colibacillosis is one of the most prevalent illnesses in pig farms. In order to examine the frequency of adherence factors and the production of enterotoxins in strains of E. coli, we collected stool specimens from 500 piglets between 1 and 10 days of age with diarrhea, including piglets from several different farms on the periphery of Mérida, Yucatán. One thousand and eighty (1080) strains of E. coli were isolated, of which 127 (11.76%) produced STa, and 62 (5.74%) produced adherence factors. Of these, 30 (48.39%) produced factor K88, 18 (29.03%) produced factor 987P, 12 (19.35%) produced K99, and 2 (3.23%) produced F41. Of the 62 strains which produced adherence factors, 42 (67.74%) also produced STa, and of these, 17 (40.84%) produced factor K88, 13 (30.95%) produced 987P, 10 (23.81%) produced K99, and 2 (4.76%) produced F41. In summary, of the 1080 strains isolated, 42 (3.89%) produced both STa toxin and adherence factors, 85 (7.87%) produced STa but did not produce adherence factors, and 933 (86.39%) produced neither STa or adherence factors. No LT-producing E. coli was detected in this study.
Assuntos
Adesinas Bacterianas/análise , Diarreia/veterinária , Enterotoxinas/análise , Infecções por Escherichia coli/veterinária , Escherichia coli/metabolismo , Doenças dos Suínos/microbiologia , Animais , Animais Recém-Nascidos , Diarreia/microbiologia , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Fezes/microbiologia , México , Suínos/microbiologiaRESUMO
Se estudió la influencia del añadido de crema de leche y leche parcialmente descremada sobre la cinética de crecimiento de Listeria monocytogenes en caldos de enriquecimiento para listerias, conteniendo diferentes concentraciones de acriflavina (15 y 7,5 mg/l). El crecimiento de Listeria monocytogenes en los caldos de enriquecimiento sufrió un retardo atribuible, al menos parcialmente, a la presencia de acriflavina. El añadido de crema de leche o leche parcialmente descremada al caldo de enriquecimiento que contiene 7,5 mg/l de acriflavina produjo un alargamiento de la fase de adaptación, pero las cosechas máximas alcanzadas a las 48 h no mostraron diferencias significativas. En presencia de 15 mg/l de acriflavina, se observó una pérdida inicial de la viabilidad de los cultivos, que fue potenciada por el agregado de crema de leche o leche parcialmente descremada al caldo de enriquecimiento. Además, la leche descremada produjo una disminución de la velocidad máxima de crecimiento que impidió alcanzar la cosecha máxima dentro de las 48 h. Los resultados obtenidos sugieren la necesidad de validar la metodología de recuperación de L. monocytogenes para cada producto, pues la eficiencia de recuperación podría ser afectada por la composición del mismo, sobre todo cuando la carga microbiana es baja (AU)
Assuntos
Listeria monocytogenes/crescimento & desenvolvimento , Laticínios , Acriflavina/análiseRESUMO
Las cepas virulentas (Bvg+) de Bordetella pertussis expresan numerosos factores de virulencia. Estos factores están regulados por el locus bvg en respuesta a estímulos ambientales, a través del proceso reversible de modulación antigénica. A su vez, mutaciones en el locus bvg originan variantes avirulentas (Bvg-) que no expresan factores de virulencia en ninguna condición de cultivo. En este trabajo hemos seleccionado variantes espontáneas Bvg- de B. pertussis Tohama I y 10536, potencialmente útiles para el estudio de marcadores de virulencia, utilizando como medios selectivos Stainer-Scholte agarizado suplementado con 1 o/o de Casamino-acids (SSA-CAS) y Jones-Kendrick con 0,20 microgramos/ml de eritromicina (JK-Ery). Paralelamente hemos estudiado la eficiencia de recuperación de células de B. pertussis Tohama 1, 10536 y 40103 (cepas Bvg+) y de la cepa Bvg- 347 (control del fenotipo avirulento) en SSA-CAS y en Steiner-Scholte agarizado (SSA), y analizado el fenotipo de las células recuperadas a partir de ellos. Para la caracterización fenotípica se utilizaron los siguientes marcadores de fase virulenta: producción de hemólisis, producción de hemaglutininas y perfiles de proteínas de fracciones enriquecidas en membrana externa. Las tres cepas Bvg+ ensayadas mostraron diferente comportamiento en estos medios. B. pertussis Tohama 1 y 10646 no crecieron en SSA, mientras que la eficiencia de recuperación en el medio SSA-CAS fue inferior al 0,001 o/o, obteniéndose variantes Bvg- estables de la cepa Tohama 1, en cambio la cepa 10536 sufrió el fenómeno de modulación, ya que recuperó el fenotipo virulento al ser subcultivada en Bordel-Gengou. El medio JK-Ery permitió seleccionar variantes Bvg- estables de B. pertussis Tohama 1 y 10536. B. pertussis 40103 mostró alta eficiencia de recuperación en SSA y SSA-CAS y retuvo el fenotipo virulento en todos los medios ensayados. Por otra parte, B. pertussis 347, a pesar de ser avirulenta, presento una eficiencia de recuperación pobre en SSA y un crecimiento escaso en JK-Ery, corroborando que no todas las cepas Bv- adquieren la capacidad de crecer en medios que resultan inhibitorios para muchas cepas virulentas (AU)
Assuntos
Bordetella pertussis/patogenicidade , VirulênciaRESUMO
Se estudió la influencia del añadido de crema de leche y leche parcialmente descremada sobre la cinética de crecimiento de Listeria monocytogenes en caldos de enriquecimiento para listerias, conteniendo diferentes concentraciones de acriflavina (15 y 7,5 mg/l). El crecimiento de Listeria monocytogenes en los caldos de enriquecimiento sufrió un retardo atribuible, al menos parcialmente, a la presencia de acriflavina. El añadido de crema de leche o leche parcialmente descremada al caldo de enriquecimiento que contiene 7,5 mg/l de acriflavina produjo un alargamiento de la fase de adaptación, pero las cosechas máximas alcanzadas a las 48 h no mostraron diferencias significativas. En presencia de 15 mg/l de acriflavina, se observó una pérdida inicial de la viabilidad de los cultivos, que fue potenciada por el agregado de crema de leche o leche parcialmente descremada al caldo de enriquecimiento. Además, la leche descremada produjo una disminución de la velocidad máxima de crecimiento que impidió alcanzar la cosecha máxima dentro de las 48 h. Los resultados obtenidos sugieren la necesidad de validar la metodología de recuperación de L. monocytogenes para cada producto, pues la eficiencia de recuperación podría ser afectada por la composición del mismo, sobre todo cuando la carga microbiana es baja
Assuntos
Acriflavina/análise , Laticínios , Listeria monocytogenes/crescimento & desenvolvimentoRESUMO
Las cepas virulentas (Bvg+) de Bordetella pertussis expresan numerosos factores de virulencia. Estos factores están regulados por el locus bvg en respuesta a estímulos ambientales, a través del proceso reversible de modulación antigénica. A su vez, mutaciones en el locus bvg originan variantes avirulentas (Bvg-) que no expresan factores de virulencia en ninguna condición de cultivo. En este trabajo hemos seleccionado variantes espontáneas Bvg- de B. pertussis Tohama I y 10536, potencialmente útiles para el estudio de marcadores de virulencia, utilizando como medios selectivos Stainer-Scholte agarizado suplementado con 1 o/o de Casamino-acids (SSA-CAS) y Jones-Kendrick con 0,20 microgramos/ml de eritromicina (JK-Ery). Paralelamente hemos estudiado la eficiencia de recuperación de células de B. pertussis Tohama 1, 10536 y 40103 (cepas Bvg+) y de la cepa Bvg- 347 (control del fenotipo avirulento) en SSA-CAS y en Steiner-Scholte agarizado (SSA), y analizado el fenotipo de las células recuperadas a partir de ellos. Para la caracterización fenotípica se utilizaron los siguientes marcadores de fase virulenta: producción de hemólisis, producción de hemaglutininas y perfiles de proteínas de fracciones enriquecidas en membrana externa. Las tres cepas Bvg+ ensayadas mostraron diferente comportamiento en estos medios. B. pertussis Tohama 1 y 10646 no crecieron en SSA, mientras que la eficiencia de recuperación en el medio SSA-CAS fue inferior al 0,001 o/o, obteniéndose variantes Bvg- estables de la cepa Tohama 1, en cambio la cepa 10536 sufrió el fenómeno de modulación, ya que recuperó el fenotipo virulento al ser subcultivada en Bordel-Gengou. El medio JK-Ery permitió seleccionar variantes Bvg- estables de B. pertussis Tohama 1 y 10536. B. pertussis 40103 mostró alta eficiencia de recuperación en SSA y SSA-CAS y retuvo el fenotipo virulento en todos los medios ensayados. Por otra parte, B. pertussis 347, a pesar de ser avirulenta, presento una eficiencia de recuperación pobre en SSA y un crecimiento escaso en JK-Ery, corroborando que no todas las cepas Bv- adquieren la capacidad de crecer en medios que resultan inhibitorios para muchas cepas virulentas