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Study of marine actinomycetes isolated from the central coast of Peru and their antibacterial activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis

Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Perú.
Revista peruana de medicina experimental y salud publica 06/2011; 28(2):237-46.
Source: PubMed

ABSTRACT

To determine the antimicrobial potential of marine actinomycetes against drug-resistant pathogens represented by strains of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE).
Strains of actinomycetes (29) isolated from marine sediment were evaluated by their characteristics in two culture media and by testing their inhibitory capacity by in vitro antagonism against multi-drug resistant (MDR) pathogenic bacteria for MRSA and VRE. Organic extracts of 3 selected actinomicetes were processed to determine the minimum inhibitory concentration (MIC) of the active compound.
Most isolated actinomycetes belong to a homogeneous group of write-gray actinomycetes with a good growth in Marine Agar. The inhibitory rates of the isolates were above 85% for both pathogens with inhibition zones greater than 69 and 78 mm in diameter for MRSA and VRE respectively. Dichloromethane extracts of 3 isolates (I-400A, B1-T61, M10-77) showed strong inhibitory activity of both pathogens, M10-77 being the highest actinomycete strain with antibiotic activity against methicillin-resistant S. aureus ATCC 43300 and vancomycin-resistant E. faecalis ATCC 51299 with a minimum inhibitory concentrations (MIC) of 7.9 and 31.7 μg/ml respectively. Phylogenetic analysis of M10-77 strain showed 99% similarity with the marine species Streptomyces erythrogriseus.
Marine sediments of the central coast of Peru, are a source of actinomycetes strains showing high capacity to produce bioactive compounds able to inhibit pathogens classified as multi-drug-resistant such as methicillin-resistant S. aureus and vancomycin-resistant E. faecalis.

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    ABSTRACT: The aim of the study was to screen the antagonistic activity of Streptomyces species isolated from marine sediment samples against drug resistant Gram positive cocci. A total of 137 strains were isolated and 15% of the actinomycetes were found to be antibiotic producers. Out of which one potential isolate showed significant inhibitory activity against ATCC strains, Methicillin resistant Staphylococcus aureus (MRSA) and Vancomycin resistant Enterococcus faecalis (VRE) and compared with standard antibiotics. Ethyl acetate extract produced a zone of inhibition of 19 mm against Staphylococcus aureus (ATCC 29213) and 21mm against Enterococcus faecalis (ATCC 29212) and 21mm against the Staphylococcus aureus (MRSA) clinical isolate. Based on Nonomura's key for classification of Streptomyces and Bergey's Manual of Determinative Bacteriology, the isolate was identified as Streptomyces albofaciens. Culturing conditions including temperature, pH, sodium chloride concentration, carbon and nitrogen sources required were optimized. Based on the results of our study Streptomyces albofaciens is found to be a promising source for novel secondary metabolites active against drug resistant pathogens.
    No preview · Article · Jul 2013 · Research Journal of Pharmaceutical, Biological and Chemical Sciences