Biological activity of roots and aerial parts of Zinnia peruviana on pathogenic micro-organisms in planktonic state and biofilm forming.

Microbial resistance to antibiotics affects the control of clinical infections and is a growing concern in global public health. One important mechanism whereby micro-organisms acquire resistance is biofilm formation. This context has led to the investigation of new antimicrobial substances from plants popularly used in folk medicine. In this work, we studied the antimicrobial and antibiofilm activity of Zinnia peruviana roots, ziniolide (major root metabolite) and aerial parts against Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The minimum inhibitory and minimum microbicidal concentration and inhibition of biofilm production was determined. All Z. peruviana extracts showed antimicrobial activity, but that corresponding to the roots was the most active one. The best inhibitory and microbicidal activity was detected against Gram-positive bacteria (0·039-0·078 mg ml-1 ). The acetonic extract from Z. peruviana leaves showed moderate activity against Gram-positive bacteria (0·625 mg ml-1 ). Acetonic extract of Z. peruviana flowers showed weak activity (1·25-5 mg ml-1 ). All the extracts tested showed inhibition of biofilm formation, as well as the ziniolide, however, roots and flowers extracts showed higher antibiofilm activity particularly against Staphylococcus, Listeria and Candida. The extracts tested may be a promising natural alternative for the control of microbial infections.

Antibacterial activity of extracts of acacia aroma against methicillin-resistant and methicillin-sensitive Staphylococcus.

Antibacterial activity of organic and aqueous extracts of Acacia aroma was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus epidermidis. Inhibition of bacterial growth was determined using agar diffusion and bioautographic methods. Among all assayed organic extracts only ethanolic and ethyl acetate extracts presented highest activities against all tested Staphylococcus strains with minimal inhibitory concentration (MIC) values ranging from 2.5 to 10 mg/ml and from 2.5 to 5 mg/ml respectively. The aqueous extracts show little antibacterial activity against Staphylococcus strains. The bioautography assay demonstrated well-defined growth inhibition zones against S. aureus in correspondence with flavonoids and saponins. A. aroma would be an interesting topic for further study and possibly for an alternative treatment for skin infections.

[Detection of Clostridium botulinum spores in honey]. / Detección de esporas de Clostridium botulinum en mieles.

A total of 177 honey samples were examined for Clostridium botulinum, 68 of which were from commercial origin, 8 from small rural producers for family consumption, and the remaining 6 from fractionizing centers in Mendoza and San Luis provinces in Argentina. C. botulinum type A was detected in two samples of rural producer origin (1.1%) by the centrifugation-dilution method. The strain was recovered from one of the samples, obtaining a spore count of 55/g of honey. Even though the positive percentage was lower than that found in other countries, honey consumption by children under one year old should be avoided in order to prevent infant botulism.

Antibacterial activity of extracts of Acacia aroma against methicillin-resistant and methicillin-sensitive Staphylococcus

Antibacterial activity of organic and aqueous extracts of Acacia aroma was evaluated against methicillin-resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus epidermidis. Inhibition of bacterial growth was determined using agar diffusion and bioautographic methods. Among all assayed organic extracts only ethanolic and ethyl acetate extracts presented highest activities against all tested Staphylococcus strains with minimal inhibitory concentration (MIC) values ranging from 2.5 to 10 mg/ml and from 2.5 to 5 mg/ml respectively. The aqueous extracts show little antibacterial activity against Staphylococcus strains. The bioautography assay demonstrated well-defined growth inhibition zones against S. aureus in correspondence with flavonoids and saponins. A. aroma would be an interesting topic for further study and possibly for an alternative treatment for skin infections.

Detección de esporas de Clostridium botulinum en mieles / Detection of Clostridium botulinum in honey

Se examinaron 177 muestras de miel para la detección de Clostridium botulinum; 68 procedentes del comercio, 95 de apiarios envasados en origen, 8 de apiarios rurales para consumo familiar y 6 de establecimientos fraccionadores en las provincias de San Luis y Mendoza. Utilizando el método de dilución-centrifugación, se detectó C. botulinum tipo A en 2 muestras de apiarios rurales de San Luis (1,1 o/o); en una de ellas se logró la recuperación de la cepa y el recuento de esporas fue de 55/g de miel. Si bien el porcentaje de positividad fue inferior al de otros países, se recomienda no suministrar miel a niños menores de 1 año como prevención de botulismo del lactante