- \(\bf Background\)
\(\textit {Streptococcus gallolyticus}\) subsp. \(\it gallolyticus\) \(\textit {(S. gallolyticus)}\) is a pathogen of infective endocarditis. It was observed previously that this bacterium survives longer in macrophages than other species and the phagocytic uptake by and survival in THP-1 macrophages is strain-dependent.
\(\bf Methods\)
The phagocytosis assay was performed with THP-1 macrophages. \(\textit {S. gallolyticus}\) specific whole genome microarrays were used for transcriptome analysis.
\(\bf Results\)
Better survival in macrophages was observed for UCN34, BAA-2069 and ATCC43143 than for DSM16831 and LMG17956. \(\textit {S. gallolyticus}\) strains show high resistance to tested bactericidal agents (acid, lysozyme and hydrogen peroxide). \(\textit {S. gallolyticus}\) stimulates significant lower cytokine gene expression and causes less lysis of macrophages compared to the control strain \(\textit {Staphylococcus aureus}\). \(\textit {S. gallolyticus}\) reacts to oxidative burst with a higher gene expression of NADH oxidase initially at the early phase. Expression of genes involved in D-alanylation of teichoic acid, carbohydrate metabolism and transport systems were upregulated thereafter.
\(\bf Conclusion\)
\(\textit {S. gallolyticus}\) is very resistant to bactericidal agents normally causing degradation of bacteria in phagolysosomes. Additionally, the D-alanylation of teichoic acid is an important factor for survival.
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