Cobalamin cbiP mutant shows decreased tolerance to low temperature and copper stress in Listeria monocytogenes

BACKGROUND: Listeria monocytogenes is a foodborne pathogen that causes listeriosis in humans. This pathogen activates multiple regulatory mechanisms in response to stress, and cobalamin biosynthesis might have a potential role in bacterial protection. Low temperature is a strategy used in the food industry to control bacteria proliferation; however, L. monocytogenes can grow in cold temperatures and overcome different stress conditions. In this study we selected L. monocytogenes List2-2, a strain with high tolerance to the combination of low temperature +copper, to understand whether the cobalamin biosynthesis pathway is part of the tolerance mechanism to this stress condition. For this, we characterized the transcription level of three cobalamin biosynthesis related genes ( cbiP , cbiB, and cysG ) and the eutV gene, a transcriptional regulator encoding gene involved in ethanolamine metabolism, in L. monocytogenes strain List2-2 growing simultaneously under two environmental stressors: low temperature (8 °C) +copper (0.5 mM of CuSO4 ×5H2O). In addition, the gene cbiP , which encodes an essential cobyric acid synthase required in the cobalamin pathway, was deleted by homologous recombination to evaluate the impact of this gene in L. monocytogenes tolerance to a low temperature (8 °C) +different copper concentrations. RESULTS: By analyzing the KEGG pathway database, twenty-two genes were involved in the cobalamin biosynthesis pathway in L. monocytogenes List2-2. The expression of genes cbiP , cbiB, and cysG, and eutV increased 6 h after the exposure to low temperature +copper. The cobalamin cbiP mutant strain List2-2Δ cbiP showed less tolerance to low temperature +copper (3 mM) than the wild type L. monocytogenes List2-2. The addition of cyanocobalamin (5 nM) to the medium reverted the phenotype observed in List2-2Δ cbiP . CONCLUSION: These results indicate that cobalamin biosynthesis is necessary for L. monocytogenes growth under stress and that the cbiP gene may play a role in the survival and growth of L. monocytogenes List2-2 at low temperature +copper.

Ceratocystis fimbriata agente causal de la enfermedad de marchitez vascular de Tectona grandis L.f. (teca) en Ecuador / Ceratocystis fimbriata causative agent of vascular wilt disease of Tectona grandis L.f. (teak) in Ecuador

Tectona grandis L.f. es una especie forestal de madera dura que, a pesar de no ser nativa de América, su plasticidad de adaptación ha permitido que en Ecuador se establezcan plantaciones intensivas con fines de exportación. Una compleja enfermedad con características de marchitez vascular está matando miles de árboles de diferentes edades en el país. Se planteó conocer el agente fitopatógeno causante de la patogénesis y muerte de los árboles. Se aislaron los hongos Fusarium sp. y Ceratocystis fimbriata Ellis & Halst. desde árboles enfermos. A nivel de invernadero se plantearon los postulados de Koch, para el efecto 30 plantas de T. grandis de cuatro meses de edad por cada tratamiento, se inocularon con los microrganismos como se describe a continuación: T1= C. fimbriata, T2 = Fusarium sp., T3 = C. fimbriata + Fusarium sp., T4 = agar-agar (control). Se empleó un diseño completo al azar (DCA) y las plantas se evaluaron a los 45 días después de inoculadas. Los tratamientos C. fimbriata, y C. fimbriata + Fusarium sp., mostraron mayores volúmenes aparentes de necrosis, con 1.52 cm3 y 1.93 cm3, y plantas muertas por la infección durante el tiempo de evaluación, mientras que Fusarium sp. mostró baja o nula patogenicidad y comportamiento similar al control, con 0.27 cm3 y 0.16 cm3 respectivamente. Estos resultados sugieren que el agente causal de la enfermedad de marchitez vascular en T. grandis es C. fimbriata y sería el primer reporte del fitopatógeno atacando teca en Ecuador. (AU)

Tectona grandisL.f. it is a hardwood forest species, which despite not being native to America, its adaptive plasticity has allowed intensive plantations to be established for export purposes in Ecuador. A complex disease with characteristics of vascular wilt is killing thousands of trees of different ages in the country. It was proposed to know the phytopathogenic agent causing the pathogenesis and death of the trees. Fusarium sp. andCeratocystis fimbriata Ellis & Halst. were isolated from diseased trees. At the greenhouselevel, Koch's postulates were proposed, for the effect 30 four month old T. grandisplants for each treatment were inoculated with the microorganisms as described below: T1 = C. fimbriata, T2 = Fusariumsp ., T3 = C. fimbriata+ Fusariumsp., T4 = agar-agar (control). A complete randomized design (DCA) was used and the plants were evaluated 45 days after inoculation. The treatments C. fimbriata, and C. fimbriata+ Fusariumsp. showed higher apparent volumes of necrosis, with 1.52 cm3and 1.93 cm3, and plants killed by the infection during the evaluation time, while Fusariumsp. showed low or no pathogenicity and behavior similar to the control, with 0.27 cm3and 0.16 cm3respectively. These results suggest that the causative agent of vascular wilt disease in T. grandisis C. fimbriataand it would be the first report of phytopathogen attacking teak in Ecuador. (AU)

Portación de Staphylococcus aureus enterotoxigénicos en manipuladores de alimentos / Carriage of enterotoxigenic Staphylococcus aureus in food handlers

BACKGROUND: One of the most common pathogens causing alimentary toxi-infections is Staphylococcus aureus (S aureus). The presence of S aureus in food, indicates flaws during food manipulations. For this reason most sanitary norms require the detection of S aureus carriers. AIM: To determine the carriage rate of enterotoxin producing S aureus strains in food handlers, and to evaluate the antibiotic susceptibility to six antimicrobial agents. MATERIALS AND METHODS: A total of 102 food handlers from 19 restaurants in Santiago, were analyzed. Samples for microbiological analysis were obtained with a swab from the retropharynx. RESULTS: S aureus grew in 35 out of the 102 samples obtained (34 per cent). Further analysis revealed that 19/35 (54 per cent) strains were able to produce enterotoxins. Therefore the corrected carriage rate was 19 per cent (19/102). The most frequently detected enterotoxin was the type A (12/19). All S aureus isolates were resistant to penicillin and susceptible to oxacillin, clindamycin, kanamycin, vancomycin and linezolid. CONCLUSIONS: The carriage rate of S aureus in food handlers in similar to the rate reported in the general population in our country. These results confirm the need for education and training programs in food safety, directed to food handlers.

Control biológico de la diarrea aguda en adultos. Restauración de la ecología intestinal como tratamiento de la diarrea

Se presenta un estudio multicéntrico doble ciego de 28 pacientes con diarrea en las cuales se prueba la eficiencia de un liofilizado de sacchomyces boulardii y se compara con un placebo.Se revisa el tema del ecosistema intestinal,la flora y su fisiología normal así como el concepto de disbacterias intestinal

Síndrome de Treacher Collins en una familia / Treacher Collins' syndrome in a family

El síndrome de Treacher Collins (STC) fue descrito por primera vez en 1846. La ocurrencia familiar ha sido bien establecida y sigue una transmisión regular dominante, con variabilidad interfamiliar e incremento en la severidad en generaciones sucesivas. Se presenta una paciente de 9 años que consulta en Policlínico de Genética por: hipoacusia, cuadros respiratorios a repetición, retraso del desarrollo psicomotor, dismorfias, observación genopatía. Es hija de padres no cosanguíneos, embarazo controlado, actividad fetal lenta, tabaquismo materno, parto eutócico, con peso y talla de nacimiento normales. Al examen físico destaca: facie angosta, oblicuidad antimongoloide de ojos, ausencia de pestañas y coloboma del borde externo del párpado inferior, hipoplasia malar, nariz de pájaro, micrognatia, implantación anormal de pelo en mejillas, comisura labial hacia arriba, hipoacusia. En antecedentes familiares destaca: madre y hermanastra con rasgos físicos similares e hipoacusia. Evaluadas las tres por Otorrino se confirma en ellas hipoacusia de transmisión bilateral y malformaciones de oído medio. El examen radiológico demuestra la hipoplasia malar. Con todos estos antecedentes se concluye que el fenotipo corresponde a un S.T.C.