Thorac Cardiovasc Surg 2023; 71(S 01): S1-S72
DOI: 10.1055/s-0043-1761680
Sunday, 12 February
Endokarditis

Cooperative Study to Address Infections and Biofilm Formation of Alloplastic Implants: Respiration of Osteoblasts Matters

L. Song
1   Center for Orthopedics and Trauma Surgery, Marburg, Allemagne
,
J. Paletta
1   Center for Orthopedics and Trauma Surgery, Marburg, Allemagne
,
S. Vogt
2   Cardiovasc Res Lab, Heart Surgery, Marburg, Allemagne
,
I. Talipov
3   Department of Cardiac Surgery, Philipps University of Marburg, Marburg, Allemagne
,
D. Sequeda-Cubides
4   Department for Cardiovascular Surgery, Heart Center, Philipps University of Marburg, Marburg, Allemagne
,
M. Irqsusi
5   Philipps University Marburg, Marburg, Allemagne
,
A. Rastan
4   Department for Cardiovascular Surgery, Heart Center, Philipps University of Marburg, Marburg, Allemagne
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Background: Alloplastic implants represent an essential part of modern surgical therapy. However, implant infections are severe complications in heart surgery. Pacemaker, heart valves, central venous catheters, or even sternal cerclage can be contaminated. Beneath Staphylococcus epidermidis, S. aureus is the most prevalent germ. Antibiotic treatment is often unsuccessful due to biofilm formation or the intracellular persistence of S. aureus. Few reports have taken S. aureus as a facultative intracellular pathogen. This study focuses on adhesion, invasion and intracellular survival of clinical isolates of S. aureus upon osteoblasts.

Method: Isolates obtained from implant-associated infections were determined by staphylococcal test and 16S rRNA sequencing. For bacteria–osteoblasts interaction studies, S. aureus ATCC 29213 and eight S. aureus isolates from patients, as well as confluent layers of osteoblast like cell lines SaOS2 and MG63 were used. Based on this model, adhesion and invasion assay with S. aureus isolates were processed. Respiration assays were performed to get the metabolic activity results of the infected osteoblasts. PCR and qPCR were applied to identify genes involved in adhesion and the corresponding expression level. Mass spectrometry was used for quantitative protein analysis.

Results: The S. aureus isolate 36 was found to adhere and invade in osteoblasts strongly. qPCR showed that clfA might be a candidate gene related to bacterial adherence, because it was overexpressed only in the adhesive S. aureus 36 and S. aureus ATCC 29213. Respiration assay indicated that metabolic activities of both SaOS2 and MG63 cell lines were stimulated after being infected with selected S. aureus isolates (9, 36, and S. aureus ATCC 29213). RC ratio of SA 36 isolates was increased. Proteome analysis of two different osteoblast cell lines with or without infection with S. aureus showed that genes involved in adhesion were mostly not expressed in osteoblasts. Only fibronectin and collagen were detectable by mass spectrometry. Otherwise, genes for elements of the mitochondrial respiratory chain were induced.

Conclusion: There is no uniform mechanism behind the adhesion of the examined S. aureus isolates, but that different adhesion proteins are involved. Beside gene and protein analysis we found different respiratory control ratios in osteoblast cell lines suggesting oxidative stress is involved in biofilm production. With respect to intracellular survival, autophagy in the host cells was turned on after infection with the S. aureus isolates tested here.



Publication History

Article published online:
28 January 2023

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