Abstract
The combination of virulence gene and antimicrobial resistance gene typing using DNA arrays is a recently
developed genomics-based approach to bacterial molecular epidemiology. We have now applied this technology
to 523 Salmonella enterica subsp. enterica strains collected from various host sources and public health and veterinary institutes across nine European countries. The strain set included the five predominant Salmonella serovars
isolated in Europe (Enteritidis, Typhimurium, Infantis, Virchow, and Hadar). Initially, these strains were screened
for 10 potential virulence factors (avrA, ssaQ, mgtC, siiD, sopB, gipA, sodC1, sopE1, spvC, and bcfC) by polymerase
chain reaction. The results indicated that only 14 profiles comprising these genes (virulotypes) were observed
throughout Europe. Moreover, most of these virulotypes were restricted to only one (n ¼ 9) or two (n ¼ 4)
serovars. The data also indicated that the virulotype did not vary significantly with host source or geographical
location. Subsequently, a representative subset of 77 strains was investigated using a microarray designed to
detect 102 virulence and 49 resistance determinants. The results confirmed and extended the previous observations using the virulo-polymerase chain reaction screen. Strains belonging to the same serovar grouped together,
indicating that the broader virulence-associated gene complement corresponded with the serovar. There were,
however, some differences in the virulence gene profiles between strains belonging to an individual serovar. This
variation occurred primarily within those virulence genes that were prophage encoded, in fimbrial clusters or in
the virulence plasmid. It seems likely that such changes enable Salmonella to adapt to different environmental
conditions, which might be reflected in serovar-specific ecology. In this strain subset a number of resistance genes
were detected and were serovar restricted to a varying degree. Once again the profiles of those genes encoding
resistance were similar or the same for each serovar in all hosts and countries investigated.
developed genomics-based approach to bacterial molecular epidemiology. We have now applied this technology
to 523 Salmonella enterica subsp. enterica strains collected from various host sources and public health and veterinary institutes across nine European countries. The strain set included the five predominant Salmonella serovars
isolated in Europe (Enteritidis, Typhimurium, Infantis, Virchow, and Hadar). Initially, these strains were screened
for 10 potential virulence factors (avrA, ssaQ, mgtC, siiD, sopB, gipA, sodC1, sopE1, spvC, and bcfC) by polymerase
chain reaction. The results indicated that only 14 profiles comprising these genes (virulotypes) were observed
throughout Europe. Moreover, most of these virulotypes were restricted to only one (n ¼ 9) or two (n ¼ 4)
serovars. The data also indicated that the virulotype did not vary significantly with host source or geographical
location. Subsequently, a representative subset of 77 strains was investigated using a microarray designed to
detect 102 virulence and 49 resistance determinants. The results confirmed and extended the previous observations using the virulo-polymerase chain reaction screen. Strains belonging to the same serovar grouped together,
indicating that the broader virulence-associated gene complement corresponded with the serovar. There were,
however, some differences in the virulence gene profiles between strains belonging to an individual serovar. This
variation occurred primarily within those virulence genes that were prophage encoded, in fimbrial clusters or in
the virulence plasmid. It seems likely that such changes enable Salmonella to adapt to different environmental
conditions, which might be reflected in serovar-specific ecology. In this strain subset a number of resistance genes
were detected and were serovar restricted to a varying degree. Once again the profiles of those genes encoding
resistance were similar or the same for each serovar in all hosts and countries investigated.
| Original language | English |
|---|---|
| Pages (from-to) | 523-535 |
| Number of pages | 13 |
| Journal | Foodborne Pathogens and Disease |
| Volume | 7 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2010 |
