Screening of marine organisms for antimicrobial and antiprotozoal activity

Ethanol extracts from a group of 53 marine organisms, including a newly identified species, from Baja California Sur (Mexico), were evaluated for their antimicrobial and antiparasitic activity. The activity against Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis (Gram), Escherichia coli (Gram) and Candida albicans (yeast) was determined by the diffusion agar method. Aplysina gerardogreeni (Demospongiae) was found to be the most active sample. In addition, A. gerardogreeni, Pacifigorgia media, and Pacifigorgia sp. possess significant activity against Mycobacterium tuberculosis H(37)Rv and Pacifigorgia media and Geodia sp. against Mycobacterium avium. From this group, 15 ethanol extracts were tested in vitro against Entamoeba histolytica and Giardia lamblia. Litotamnium crassiussculum, Geodia sp., Pacifigorgia sp. showed significant activity against Entamoeba histolytica while Myxilla incrustans and Muricea appressa were active against Giardia lamblia. Litotamnium crassiussculum showed activity against both trophozoites.