## 3 Results and Discussion
Three _Salmonella_ serovars, \(S\). Typhimuriumium (two strains, ATCC 14028, and UK-1), \(S\). Enteritidis, and \(S\). Heidelberg, were compared in HD11 cell culture experiments (Tables 4 and 5). For HD11 cells, attachment percentages were generally greater (Table 4) for \(S\). Heidelberg and \(S\). Typhimuriumium ATCC 14028 than those observed for these strains in Caco-2 cell cultures (Table 2) and exhibited higher rates for invasion, ranging from 2.9 to 17.6% (Table 5) compared to Caco cell invasion percentages (Table 3). \(S\). Heidelberg, \(S\). Typhimuriumium ATCC 14028, and \(S\). Typhimuriumium UK-1 exhibited the greatest levels of percent attachment (_p_ < 0.05), with \(S\). Enteritidis attachment being less than half the other servovars (18.6 \(\pm\) 2.42%). _Salmonella_ Typhimurium strain UK-1 invaded HD11 cells at higher percentages, 17.6 \(\pm\) 3.29, likely due to the strain's high virulence phenotype. _Salmonella_ Typhimurium UK-1 (abbreviated for \"universal killer\") is a highly virulent strain initially isolated in 1991 from an infected horse and passaged through a chicken [34]. _Salmonella_ Typhimurium ATCC 14028 (9.3 \(\pm\) 0.57) and UK-1 (17.6 \(\pm\) 3.29)'s respective invasion levels of HD11 cells support that strain differences can occur within the same serovar. [PERSON] et al. [34] conducted an extensive genome analysis comparing UK-1 and other \(S\). Typhimuriumium strains. They reported that virulence factors from one strain may increase or decrease virulence from another [35]. The identification of polymorphic genomic regions of the strains and further analyses revealed that even highly similar strains of \(S\). Typhimuriumium could be distinguished [35]. [PERSON] et al. [35] reported that mutants of \(S\). Typhimuriumium UK-1 were less invasive of HD11 cells than the wildtype strain. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Bacterial Strain** & **Log Dilution** & **\# of Colonies** & **\# Bacteria Added** & **\# Bacteria Adhering** & **\% Adhesion \({}^{*}\)** \\ \hline \(S\). Heidelberg & 4 & 59.6 \(\pm\) 15.96 & 1.3 \(\times\) 10\({}^{7}\) \(\pm\) 0.47 & 5.5 \(\times\) 10\({}^{6}\) \(\pm\) 1.98 & 43.4 \(\pm\) 7.46 \({}^{\text{a}}\) \\ \(S\). Typhimuriumium ATCC 14028 & 4 & 61.8 \(\pm\) 17.58 & 1.6 \(\times\) 10\({}^{7}\) \(\pm\) 0.47 & 6.2 \(\times\) 10\({}^{6}\) \(\pm\) 1.15 & 38.7 \(\pm\) 4.57 \({}^{\text{a}}\) \\ \(S\). Typhimuriumium UK-1 & 4 & 69.2 \(\pm\) 19.85 & 1.8 \(\times\) 10\({}^{7}\) \(\pm\) 0.71 & 7.0 \(\times\) 10\({}^{6}\) \(\pm\) 1.93 & 38.9 \(\pm\) 9.24 \({}^{\text{a}}\) \\ \(S\). Enteritidis & 4 & 39.2 \(\pm\) 9.24 & 2.1 \(\times\) 10\({}^{7}\) \(\pm\) 0 & 3.9 \(\times\) 10\({}^{6}\) \(\pm\) 0.50 & 18.6 \(\pm\) 2.42 \({}^{\text{b}}\) \\ \hline \hline \end{tabular}  
\({}^{*}\) Percentages not connected by the same letter are significantly different between each assay (_p_ < 0.05).  
\end{table} 
Table 4: Adhesion of four _Salmonella_ strains from different serovars to chicken macrophage HD11 cells. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Bacterial Strain** & **Log Dilution** & **\# of Colonies** & **\# Bacteria Added** & **\# Bacteria Adhering** & **\% Adhesion** \\ \hline \(S\). Typhimuriumium ATCC 14028 & 4 & 17.67 \(\pm\) 2.31 & 9.83 \(\times\) 10\({}^{6}\) \(\pm\) 0 & 1.78 \(\times\) 10\({}^{6}\) \(\pm\) 0.25 & 18.1 \(\pm\) 6.25 \\ \(S\). Heidelberg ARI-14 & 4 & 26.0 \(\pm\) 2.83 & 9.13 \(\times\) 10\({}^{6}\) \(\pm\) 0 & 2.63 \(\times\) 10\({}^{6}\) \(\pm\) 0.32 & 28.8 \(\pm\) 6.37 \\ \hline \hline \end{tabular}  
\({}^{*}\) Adhesion between \(S\). Heidelberg and Typhimurium was not significantly different (_p_ > 0.05).  
\end{table} 
Table 2: _Salmonella_ Typhimuriumurium and \(S\). Heidelberg adhesion to human epithelial Caco-2 cells.