Comparative phytochemical evaluation, antimicrobial and antioxidant properties of Pleurotus ostreatus

This study scientifically examined the phytochemistry, antioxidant and antimicrobial potencies of two organic extracts of Pleurotus ostreatus. Generally, both extracts were effective against 89.8% of theisolates tested with Bacillus subtilis (7.6 – 7.8 mm), Escherichia coli (7.6 – 8.2 mm) and Saccharomycee cerevisae (10.5 – 10.8 mm) exhibiting highest gram ±ve, gram –ve and fungal susceptibilities by agar well diffusion method, respectively. However, petroleum ether extract (PE) exhibited greater anti-gram negative bacterial activity than the acetone extract (AE) and further produced growth inhibition of theseisolates in broth. Compared to PE, the acetone extract elicited higher total phenolic content and in vitro antioxidant capacity. Phytochemical analyses of the extracts revealed low to moderate levels of terpenoids, tannins, steroidal glycosides and carbohydrates, while flavonoids, alkaloids and cynogenic glycosides were not detected. The results indicate that P. ostreatus possesses antimicrobial and antioxidant potentials

Multirresistência a antimicrobianos mediada por plasmídios R em cepas de Shigella flexneri isoladas no nordeste do Brasil Multiple antibiotic-resistance mediated by R plasmid in Shigella flexneri strains isolated in the Northeast of Brazil

Em amostras de S. flexneri, isoladas no período de 1989 a 1993, foi estudado o mecanismo molecular que mediava a multirresistência. Foram utilizadas no estudo 26 amostras de S. flexneri. Estas amostras foram submetidas a teste de sensibilidade a antimicrobianos, experimentos de conjugação e extração de plasmídios. Com relação ao padrão de resistência a antimicrobianos, observou-se que todas as amostras de S. flexneri eram resistentes a pelo menos três antimicrobianos. Das 26 amostras de S. flexneri doadoras submetidas ao processo de conjugação, 34,6% (9 amostras) resultaram em uma freqüência variável de transconjugantes. Das amostras que conjugaram, 100% transferiram o fator de resistência relacionado à ampicilina; sendo que em todas as transconjugantes foi evidenciado apenas um plasmídio de 23,1Kb. Este plasmídio, encontrado em todas as amostras de Shigellas, caracterizou-se como o portador de marca de resistência para ampicilina.<br>In Shigella strains were studied the molecular mechanism that mediated the multiply antibiotic-resistance. Twenty-six strains of Shigella flexneri were utilised in this investigation. These strains were submitted to disk diffusion test, mating experiments and plasmid isolation. In relation to antibiotics resistance standard it was observed that all Shigella flexneri strains were resistant to at least, three antibiotics tested. From twenty-six Shigella flexneri strains donors submitted to conjugation process, 34.6% (nine strains) resulted in variable frequency of transconjugants. From strains that conjugated, 100 %, transferred the resistance factor acquainted with ampicillin. Being that, in all transconjugants which were observed, just one plasmid with 23.1Kb was evidenced. This plasmid found in all strains was characterised as the causer of resistance to ampicillin