The presence of major world-wide clones for phage type 4 and 8Salmonella entericaserovar Enteritidis and the evaluation of their virulence levels by invasiveness assaysin vitroandin vivo

Abstract

Seventy-seven animal isolates of Salmonella enterica serovar Enteritidis (S. Enteritidis) obtained from the United States were analyzed by phage typing and pulsed field gel electrophoresis (PFGE). Thirty-nine strains were found with phage types (PT) 4, 8, and 13a. When the chromosomal DNA of these 39 isolated strains with PT4, 8, and 13a were digested with XbaI, SpeI and NotI, followed by PFGE analysis, 28 strains were found with a pattern combination of X4S4N4, which was the major subtype. When PFGE patterns of the US isolates with PT 4 and 8 were compared with those of the Taiwanese and German isolates, pattern X3S3N3 was confirmed to be the world-wide subtype shared by PT 4 isolates, as previously reported, while pattern X4S4N4 was newly found to be the most common subtype shared by PT 8 strains. The presence of such major world-wide clones, however, does not necessarily mean that these clones are highly virulent, at least not according to the results of invasiveness assays using cultured human intestinal epithelium cell line Int-407 and living BALB/mice.

Cell invasion of poultry-associated Salmonella enterica serovar Enteritidis isolates is associated with pathogenicity, motility and proteins secreted by the type III secretion system

“…Fewer studies have been conducted to determine differences in invasiveness of field isolates of S. Enteritidis (Pan et al, 2009;Pang et al, 2006;Solano et al, 1998). Although these studies have shown that not all isolates of S. Enteritidis have similar cell invasive potential, only limited numbers of isolates recovered mostly from human, animal, food and the environment were tested.…”

“…Regardless of phage types, geographical origins or source of isolation, S. Enteritidis is one of the most genetically homogeneous serotypes of Salmonella and as a result is poorly discriminated by the commonly used genetic subtyping methods, such as phage typing, pulsed field gel electrophoresis or comparative genomic hybridization microarrays (Betancor et al, 2009;Botteldoorn et al, 2010;Hudson et al, 2001;Liebana et al, 2001;Malorny et al, 2008;Morales et al, 2005;Olsen et al, 1999;Pan et al, 2009;Pang et al, 2006;Porwollik et al, 2005;Saeed et al, 2006;Swaminathan et al, 2001). Because of its greater discriminatory capacity, MLVA was used to assess the genetic similarity among S. Enteritidis isolates tested in this study Cho et al, 2007;Malorny et al, 2008).…”

“…However, only two strains from each source were tested (Humphrey et al, 1996). Similarly, Pang et al (2006) showed that poultryassociated strains of S. Enteritidis differed in their invasion potential in cultured Int-407 cells, but only eight strains were tested. Despite poultry being a reservoir host for S. Enteritidis and a major source of human infection worldwide, it is still unclear if differential pathogenicity translates into differential risk for human.…”

PCR Detection of Four Virulence-Associated Genes of Campylobacter jejuni Isolates from Thai Broilers and Their Abilities of Adhesion to and Invasion of INT-407 Cells

“…In this study, we examined the ability of Campylobacter jejuni strains isolated from the caecal contents of broilers to adhere to and invade the cells of the INT-407 human intestinal cell line and determined the association with the presence of certain virulence genes which affect on poultry colonization [43,44] and the adherence and invasion abilities of Campylobacter jejuni isolates. The adherence and invasion abilities of the caecal isolates varied considerably, from invasive levels similar to that of [6,25,33]. Even though the process of Campylobacter adhering to and invading INT-407 human intestinal epithelial cells in culture does not exactly mimic the process in vivo, the cell culture model allowed us to determine the relative adherence and invasion abilities of the caeca isolates in comparison to well-studied human clinical strain C. jejuni 81116.…”

Severe infections caused bySalmonellaEnteritidis PT8/7 linked to a private barbecue

“…3 %) were identified as PT 8/7. This phage type is mainly associated with chicken eggs [3] and is not known for particularly high virulence [4] or pathogenicity [5].…”