Different susceptibilities of Aedes aegypti and Aedes albopictus larvae to plant-derived products

INTRODUCTION

Aedes aegypti and Aedes albopictus are important vectors that transmit arboviruses to human populations.

METHODS

Natural products were obtained and tested against larvae collected from the field in Fortaleza, capital of Ceará state.

RESULTS

The essential oils of Syzygium aromaticum (Ae. aegypti LC50 = 32.7 ppm and Ae. albopictus LC50 = 138.1 ppm) and Croton nepetaefolius (Ae. aegypti LC50 = 81.7 ppm and Ae. albopictus LC50 = 76.1 ppm) showed the most intense larvicidal activity.

CONCLUSIONS

The essential oils and methyl esters showed greater larvicidal activity than did the ethanol extracts.

Modulation of the resistance to norfloxacin in Staphylococcus aureus by Bauhinia forficata link

Microdilution assays were performed in order to evaluate the antimicrobial activity of the ethanoic extract from the leaves of Bauhinia forficate (EEBF) against different microorganisms. The extract did not present inner antimicrobial activities against the tested strains. However, EEBF was able to modulate the norfloxacin-resistance against Staphylococcus aureus SA1199-B that overproduce the NorA efflux pump, once sub-inhibitory concentrations of EEBF reduced the minimal inhibitory concentratio of the norfloxacin in 87.5%. This modulatory effect was also found when the antibiotic was replaced by ethidium bromide, suggesting that EEBF acts probably by inhibition of NorA, allowing the antibiotic accumulation intracellularly, and making the line more sensitive. These results point out the EEBF potential as a source of NorA inhibitors that could be used in combination with norfloxacin for treatment of infections caused by multidrug-resistant S. aureus.