ARS | Publication request: Microarray analysis of Inc A/C Plasmids in a population of Multidrug resistant Salmonella enterica

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 2010
Publication Date: May 23, 2010
Citation: Lindsey, R.L., Cray, P.J., Frye, J.G., Meinersmann, R.J. 2010. Microarray analysis of Inc A/C Plasmids in a population of Multidrug resistant Salmonella enterica. American Society for Microbiology. May 23-27, 2010. San Diego, CA. Poster #A-2502.

Technical Abstract: Bacteria plasmids are fragments of extra-chromosomal double stranded deoxyribonucleic acid (DNA) that can contain a variety of genes beneficial to the survival of the host bacteria. Classification and tracking of bacterial plasmids is valuable for the study of horizontal gene transfer of drug resistance. Plasmids can be classified according to incompatibility (Inc) types which are based on the inability of plasmids with the same replication mechanism to exist in the same cell. In Enterobacteriaceae there are 26 described Inc or replicon types. Certain replicon types such as Inc A/C are associated with multidrug resistance (MDR). We developed a hybridization microarray that contains 288 unique 70mer oligonucleotide probes based on sequence from five Inc A/C plasmids: pYR1 (Yersinia ruckeri str. YR71), pPIP1202 (Yersinia pestis biovar Orientalis str. IP275), pP990180 (Photobacterium damselae subsp. Piscicida), pSL254 (Salmonella enterica subsp. enterica serovar Newport str. SL254) and pP91278 (Photobacterium damselae subsp. Piscicida). DNA from a population of 59 Salmonella enterica isolates was hybridized to the microarray and analyzed for the presence/absence of genes. These isolates represented 17 serovars from 14 different host sources and were geographically discrete throughout the US. Qualitative cluster analysis was performed using Cluster 3.0 to group microarray hybridization results in Excel. While multiple groups of contiguous genes were present in the isolates indicating the presence of Inc A/C plasmids, regions of variability were found in a subset of isolates that differentiated two lineages of Inc A/C plasmids. Unexpected variability was found in hybridization on the array to pSL254 oligos. Genes associated with mercuric resistance were conserved in a number of groups of isolates. Our results suggest that while there is a common Inc A/C backbone, a degree of variability in the composition of genes present in the Inc A/C plasmids analyzed in this study suggests diversity within the population which may be important in the development of MDR. The conservation of mercuric resistance genes suggests they are an important component of the backbone.