EPIDEMIOLOGY, ECOLOGY, AND MOLECULAR GENETICS OF ANTIMICROBIAL RESISTANCE IN PATHOGENIC AND COMMENSAL BACTERIA FROM FOOD ANIMALS
Location: Bacterial Epidemiology and Antimicrobial Resistance
Title: Rapid Detection of Antimicrobial Resistance Genes in Salmonella Serovars using DNA Microarray Technology
| Nayak, Rajesh - FDA, NTCR |
| Wen, Zou - FDA, NTCR |
| Liu, Jiajian - FDA, NTCR |
| Stormo, Gary - FDA, NTCR |
Submitted to: American Society for Microbiology Conference
Publication Type: Abstract Only
Publication Acceptance Date: February 16, 2007
Publication Date: May 24, 2007
Citation: Nayak, R., Wen, Z., Frye, J.G., Liu, J., Stormo, G. 2007. Rapid Detection of Antimicrobial Resistance Genes in Salmonella Serovars using DNA Microarray Technology [abstract]. American Society for Microbiology Conference. 304/Z(Z-082):745.
Selective pressure resulting from use of antimicrobials by the food animal industry and human health care may be a source for the development of resistance among food borne pathogens, such as Salmonella. Detection of drug resistance mechanisms in Salmonella serovars can be critical when treatment of salmonellosis is indicated. Microarray technology was evaluated as an antimicrobial resistance (AR) detection method for Salmonella isolated from on-farm sources. 34 Salmonella isolated from a Turkey farm were analyzed with a DNA microarray containing 775 (AR) gene probes (Frye, et al., IJAA, 2006;27(2):138-150). DNA extraction, labeling, hybridization, scanning, data analysis and controls were performed as previously described. The Salmonella isolates exhibited very diverse genotypic profiles. Approximately 153 gene probes had positive hybridizations with at least one isolate. The most often detected genes encoded resistance to aminoglycosides, tetracycline, sulfonamides, quaternary ammonium, and '-lactams as well as mobile genetic elements. Salmonella Heidelberg strains (n=23) exhibited hybridizations to aminoglycosides (aadA1, aadA1b and aadE), '-lactams (blaSME-1), Quaternary ammonium salts (qac), and sulfonamides (sul1), Class I integron (intI) and transposon (tnpM) gene probes. Hybridization results from Heidelberg strains correlated well with the phenotypic AR susceptibility data. Resistance genes were not detected in serotype Anatum, Muenster, Senftenberg and Worthington isolates (n=6), however, phenotypic AR susceptibility data showed resistance to multiple drugs. Un-typed Salmonella “rough” isolates (n=5) exhibited hybridization to resistance genes identical to Heidelberg, and also to tetracycline resistance genes (tetA and tetR). Interestingly, the genes encoding chloramphenicol, efflux pumps, macrolides, streptothricin and trimethoprim were absent in all serovars. Detection methods such as microarray analysis can aid public health laboratory identification of drug resistance and treatment of infections due to accidental or bio-terror Salmonella outbreaks.