Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: August 30, 2001
Publication Date: N/A
Technical Abstract: Recent reports have suggested that feeding antimicrobial compounds to animals as growth promotants may result in increased microbial resistance to antibiotics. Fecal and manure storage pit samples were collected from a local swine facility, where tylosin was the only antibiotic added to the feed. Antibiotic resistant (AR) bacteria were enumerated by plating onto complex media containing tetracycline (10 ug/ml), erythromycin (10 ug/ml), or tylosin (10 ug/ml). AR bacteria were found in all samples. Pure cultures of AR bacteria were isolated for identification by 16S rDNA gene sequence analyses and further characterization of AR. Similarity analyses of the 16S rDNA sequences indicated the presence of primarily low G+C, Gram-positive bacteria. A variety of erythromycin resistant strains were positive in PCR tests for the presence of different classes of erm genes, including ermA, B, C, F, G, and T. Total DNA preparations were also tested dwith the AR gene PCR primers and the products randomly cloned and sequence for similarity analyses with known AR genes. The finding of a high number of identified and unidentified AR eubacteria in swine feces and manure storage pits suggest that these ecosystems may serve as potential reservoirs of antibiotic resistance genes.