Selection for Triclosan Resistance Causes Antibiotic Resistance in Pseudomonas aeruginosa but Not Escherichia coli
Triclosan is a widely used antimicrobial, found in hand sanitizer, soap, and many personal hygiene products include body deodorants, but studies by Cottell et.al (2009) and Braoudaki and Hilton (2004) have pointed out that triclosan tolerant bacteria may develop cross resistance to other antibiotics. Thus, the over usage of triclosan could select for antibiotic resistant bacteria. The cross-resistance hypothesis is being retested in this study. By exposing wild-type bacteria to five rounds of selection, I created five populations of triclosan-resistant Eschericia coli and five populations of triclosan-resistant Pseudomonas aeruginosa. Simultaneously, I established five unselected populations of each of the two species as a control. I then exposed both selected and unselected populations to 1) 10μL 0.45% triclosan, 2) 5mcg ciprofloxacin, and 3) 10mcg streptomycin and measured resistance to each. Although E. coli acquired increased triclosan resistance after selection, it did not develop cross-resistance to either of the two antibiotics. P. aeruginosa developed resistance to ciprofloxacin after selection for triclosan resistance, but did not show increased resistance to streptomycin. Interestingly, P.aeruginosa strains displayed decreased resistance to triclosan after selection, a result that was confirmed in a replicate study.
Biology Dept, Wofford College, Spartanburg, SC
163 • Mai H. Tran, Joong-Wook Park
Tarballs on Freshwater Shoreline as Reservoirs for Pathogens
Tarballs are remnants of petroleum found on the shoreline after an oil spill or oil seep. They are considered a contaminant to the environment and much research has focused on the potential of the hydrocarbonoclastic microbes present in them. The study by Tao et al. in 2010 was the first to reveal that marine tarballs could pose a hazard to human health because they could act as reservoirs for pathogens. In their research, tarball samples collected on the Gulf of Mexico beaches were found to contain Vibrio vulnificus at ten to a hundred times higher than the amount normally observed in marine environments. This study proposes to investigate tarballs collected on the shoreline of Lake Pontchartrain, Louisiana, to validate the hypothesis that pathogenic bacteria also accumulate in freshwater or brackish water tarballs. DNA extracted from the bacterial samples will be analyzed using PCR-DGGE and BLAST techniques to identify the microbial groups present.
Dept of Biological and Environmental Sciences, Troy University, Troy, AL.
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164 • Amanda N. Hyre, Philip Rock
Wolbachia Infection in a Local Strain of the Common Fruitfly Drosophila melanogaster
Wolbachia are obligate, intracellular prokaryotic endosymbionts present in a wide variety of arthropod hosts. It is estimated that from 20-70 per cent of insect species harbor this organism. The endosymbiont is maternally inherited. In some species, certain strains of Wolbachia are known to affect reproduction in a number of different ways, including: feminization of males, male killing, or reproductive isolation due to cytoplasmic incompatibility between infected and uninfected insects. A locally obtained strain of fruitfly is shown to be infected with Wolbachia, as detected by a polymerase chain reaction (PCR) amplification of the gene for a conserved Wolbachia surface protein (wsp). This strain has been cured’ of the endosymbiont by treatment with the antibiotic tetracycline. Here it is demonstrated that cultures derived from Wolbachia-infected females produce significantly fewer progeny than cultures from uninfected females. The maternal inheritance of Wolbachia in the local strain is supported by PCR analysis of crosses involving pair-wise combinations of infected and uninfected fly strains.
Biology Dept, Virginia Wesleyan College, Norfolk, VA.
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165 • Annette M. Golonka, Bettie Obi Johnson, Jonathan Freeman, Daniel W. Hinson
Impact of Nectarivorous Yeasts on Silene caroliniana’s Scent
Silene caroliniana is considered a scentless flower, but is insect-pollinated and produces a nectar reward. This plant is host to nectar-associated Metschnikowia yeast species. In this study, the scent profile of S. caroliniana is determined, and the contribution of nectar inhabiting yeasts to its scent is evaluated using solid phase micro-extraction and gas chromatography-mass spectrometry (SPME-GC-MS). The scent compounds produced by nectar isolated Metschnikowia species are identified and their impact on the flowers’s scent is determined. Analyses of the scent profiles of unvisited nectar, unvisited flowers, and visited nectar confirm that this plant produces few scented compounds unless microbial organisms are present in the nectar. Metschnikowia species contribute aliphatic alcohols, including ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol, and2-methyl-1-butanol to S. caroliniana’s scent.
Math,, Science, Nursing, and Public Health, University of South Carolina Lancaster, Lancaster, SC
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166 • Henry G. Spratt, Jr., Martin M. Brown, Erin Liner, William C. Hayes
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