Growth of Community-Acquired MRSA strain USA300 Multi-drug Transporter Mutants is inhibited by Extracts of Tyrol Knapweed, Centaurea nigrescens.


  • Kyra P. Lasko
  • Kyra P. Lasko
  • Kathryn D. Robinson West Virginia Wesleyan College
  • Kathryn D. Robinson West Virginia Wesleyan College


MRSA, Genetic screen


The rates of infection by community-acquired multi-drug resistant Staphylococcus aureus (CA-MRSA) have risen dramatically over fifteen years in the United States.  CA-MRSA is responsible for rapidly progressive diseases, including necrotizing pneumonia, severe sepsis, and necrotizing fasciitis.  Consequently, novel antibacterial strategies are needed to combat the rising antibiotic resistance seen in CA-MRSA strains.  The USA300 CA-MRSA strain has been mutagenized using the Bursa aurealis transposon to create the Nebraska Transposon Mutant Library (NTML). We have screened the 1920 non-essential, defined transposon insertions in the NTML for strains that are either susceptible or resistant to methanol extracts of Centaurea nigrescens (CnME) leaves and flowers. 30 strains containing mutations affecting transporter proteins were identified as having either significant resistance or susceptibility to Centaurea extract.  Insertions in two different drug efflux transporter families have been identified. The EmrB/QacA drug resistance transporter subfamily is a multi-drug efflux pump responsible for the export of toxic molecules from bacteria and yeast. The ABC transporters are involved in drug import and export. These results confirm the effectiveness of the screen as a means for identifying drug-resistance genes affected by the C. nigrescens methanolic extract and suggest a role for drug efflux proteins in the resistance of S. aureus CA-MRSA to antibacterial plant metabolites. Current work is focused on determining the effect of CnME on the expression of selected drug-resistance transporters via qRT-PCR.


Author Biographies

Kyra P. Lasko


Kyra P. Lasko


Kathryn D. Robinson, West Virginia Wesleyan College


Kathryn D. Robinson, West Virginia Wesleyan College



Bach, S.M.; Fortuna, M.A., Rodgoun, A., de Trimarco, J.T., Yossef, A.G., Bach, H. 2011. Antibacterial and cytotoxic activities of the sesquiterpene cnicin and onopordopicrin., Natural Products Communication 6(2):163-6.

Bauer, A.W., Kirby, W.M.M., Sherris, J.C., and Turck, M. 1966. Antibiotic susceptibility testing by a standardized single disk method. The American Journal of Clinical Pathology 45(4): 493-496.

Bose, J.L., Fey , P.D., and Bayles, K.W. 2013. Genetic tools to enhance the study of gene function and regulation in Staphylococcus aureus. Appl Environ Microbiol. Apr;79(7):2218-24. doi: 10.1128/AEM.00136-13.

Broz, A.; Broeckling, C.; He, J.; Dai, X., Zhao, P.; Vivanco, J. 2007. A first step in understanding an invasive weed through its genes: an EST analysis of invasive Centaurea maculosa. BMC Plant Biology 7:25. doi:10.1186/1471-2229-7-25.

Cansaran, A., Dogan, N.M., Oztekin, M., and Acar, G. 2010. Antimicrobial activity of various extracts of Centaurea cankiriense A. Duran and H. Duman. African Journal of Microbial Research, 4(8) 608 – 612.

Durant E. A nickel ABC-transporter of Staphylococcus aureus is involved in urinary tract infection. Mol Microbiol. 2010 Sep;77(5):1246-60. doi: 10.1111/j.1365-2958.2010.07287.x. Erratum in: Mol Microbiol. 2010 Nov;78(3):788.

McDougal, L.K., Steward, C.D., Killgore, G.E., Chaitram, J.M., McAllister, S.K., and Tenover, F.C. 2003. Pulsed-field gel electrophoresis typing of oxacillin-resistant Staphylococcus aureus isolates from the United States. establishing a national database. J Clin Microbiol. Nov; 41(11):5113-20.

Millar, B., Prendergast, B.D., Moore, J.E. 2008. Community-associated MRA (CA-MRSA): an emerging pathogen in infective endocarditis. The Journal of Antimicrobial Chemotherapy 61(1) 1 – 7.

Peschel, A., and Gotz, F. 1996. Analysis of the Staphylococcus epidermidis Genes epiF, -E, and -G Involved in Epidermin Immunity. Journal of Bacteriology 178(2), 531–536.

Sarker SD, Nahar L, Kumarasamy Y. 2007. Microtitre plate-based antibacterial assay incorporating resazurin as an indicator of cell growth, and its application in the in vitro antibacterial screening of phytochemicals. Methods. 42(4):321-4.

Stavri, M., Piddock, L.J.V., and Gibbons, S. 2007. Bacterial efflux pump inhibitors from natural sources. Journal of Antimicrobial Chemotherapy 59, 1247–1260.

USDA, NRCS. 2014. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA. Accessed 7 February 2014.

Zengin, G., Aktumsek, A., Guler, G., Cakmak, Y., and Yildiztugay, E. 2011. Antioxidant Properties of Methanolic Extract and Fatty Acid Composition of Centaurea urvillei DC. subsp. hayekiana Wagenitz. Records Of Natural Products, 5(2), 123-132.




How to Cite

Lasko, K. P., Lasko, K. P., Robinson, K. D., & Robinson, K. D. (2018). Growth of Community-Acquired MRSA strain USA300 Multi-drug Transporter Mutants is inhibited by Extracts of Tyrol Knapweed, Centaurea nigrescens. Proceedings of the West Virginia Academy of Science, 90(1). Retrieved from



Meeting Abstracts-Poster