Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/28/2012
Publication Date: 10/12/2012
Citation: Brunelle, B.W., Bearson, S.M., Bearson, B.L. 2012. Identification of multidrug-resistant Salmonella enterica serovar typhimurium isolates that have an antibiotic-induced invasion phenotype [abstract]. In: Proceedings of Annual North Central Branch of the American Society for Microbiology. Fargo, North Dakota. October 12-13, 2012. p. 10.
Technical Abstract: Multidrug-resistant (MDR) Salmonella is an important food safety issue in humans and animals. The National Antimicrobial Resistance Monitoring System (NARMS) has reported that 27.3% of Salmonella enterica serotype Typhimurium isolates in humans were resistant to three or more classes of antibiotics, and 20.8% were resistant to five or more classes. It has been demonstrated in some bacteria that antibiotics can alter regulation of cellular processes, including invasion. In the current study, the invasion phenotype of several MDR S. Typhimurium isolates was tested following exposure to various antibiotics in vitro. We employed real-time RT-PCR to measure the expression of genes associated with invasion, as well as tissue culture assays to phenotypically evaluate cellular invasion. In a subset of the isolates, invasion could be induced during early-log (non-invasive) growth phase; this phenotype was dependent on the antibiotic type and concentration. Invasion was not increased when antibiotics were added in the late-log (normally invasive) growth phase. Characterizing the effects of antibiotics on Salmonella invasiveness and virulence will enhance our understanding of their impact on both animal and human health.