A search for Streptomyces species which inhibit growth of drug-resistant bacterial pathogens

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Muller, Madeleine
McKillip, John L.
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Multidrug resistant pathogens continue to reach new heights and there is currently no new antibiotic classes available. This is because of improper use of antibiotics in developed and developing countries as well as livestock. Improper use allows the pathogen to be exposed and develop mechanisms to fight off the antibiotic. Some of these mechanisms include: ribosomal inactivation, target site modifications, impermeability, efflux pumps, and antimicrobial inactivation. Currently 6 pathogens named the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) have been listed as the most alarming for resistance to antibiotics. To combat this crisis, I looked in a dairy environment for Streptomyces species that produced antimicrobial metabolites. I collected samples of raw milk, soil, trough water, manure, and corn silage and overlayed them against an ESKAPE pathogen looking for a zone of inhibition. Once a zone of inhibition was found the species was isolated and retested to confirm. If confirmed, a Gram stain was performed to determine biochemical test for identification of the unknown isolates genus. Finally, PCR on the 16S region was completed for sequencing to confirm the genus and species of the unknown. Using these methods, 21 isolates were identified to produce zones of inhibition against S. aureus, E. faecium, and P. aeruginosa. Isolates 4 is believed to be B. cereus and isolate 6 and 9 is believed to be B. subtilis. Both of these species have been researched in the past for their antimicrobial properties. These findings suggest that there are many species left to be discovered for their antimicrobial properties that could help slow the antibiotic crisis.