The microbiological characteristics of Staphylococcus aureus causing infective endocarditis (IE) have not been investigated thoroughly. We compared the characteristics of S. aureus isolates from patients with and without IE. Cases of S. aureus bacteremia (SAB) were collected from 10 hospitals over 7 years. Cases of native valve IE were matched with non-IE controls according to the following criteria: central-line-associated infection, community-acquired infection, methicillin susceptibility, and if possible, the primary site of infection. Genes coding virulence factors were analyzed using multiplex polymerase chain reactions. Fibrinogen and fibronectin-binding properties were assessed using in vitro binding assays. The fibronectin-binding protein A gene (fnbpA) was sequenced. Of 2,365 cases of SAB, 92 had IE. After matching, 37 pairs of S. aureus isolates from the IE cases and non-IE controls were compared; fnbpA was detected in 91.9% of the IE isolates and 100% of the non-IE isolates (p = 0.24). While the fibrinogen binding ratio was similar (1.07 ± 0.33 vs. 1.08 ± 0.26, p = 0.89), the fibronectin-binding ratio was significantly higher in the IE-group (1.31 ± 0.42 vs. 1.06 ± 0.31, p = 0.01). The proportions of major single-nucleotide polymorphisms in fnbpA were as follows: E652D (2.9% vs. 2.7%), H782Q (65.6% vs. 60.6%), and K786N (65.6% vs. 72.7%). The fibronectin-binding ratio was positively correlated with the number of SNPs present in IE cases (p < 0.001) but not in the non-IE controls (p = 0.124). Fibronectin-binding might play a key role in SAB IE. However, the degree of binding may be mediated by genetic variability between isolates.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea [NRF-2016R1C1B2011720]; Seoul National University Bundang Hospital (SNUBH) Research Fund [13-2016-008]. Staphylococcus aureus laboratory strains 8325-4 (FnBP-A+B+) and DU 5883 (FnBP-A−B−) were kindly provided by Dr. Timothy J. Foster, Department of Microbiology, Trinity College, Dublin, Ireland. We thank the members of the Korea Infectious Diseases (KIND) study group and the associated staff for their cooperation in this study. In addition to the authors, the following individuals participated in the study group: Jeong Eun Cho, Yun Jung Choi, and Jung In Park (Seoul National University Bundang Hospital); Sook-In Jung, Seung-Ji Kang (Chonnam National University Hospital); Kye-Hyung Kim (Pusan National University Hospital); Hyo Youl Kim, Hee Kyoung Choi and Myung Sook Han (Yonsei University Wonju College of Medicine); Yeon-Sook Kim (Chungnam National University Hospital); Chong Rae Cho, Hyun Suk Song, and Young Soon Lee (Inje University Ilsan Paik Hospital); Ki Tae Kwon, Hye-In Kim (Daegu Fatima Hospital). Jae Hyun Jeon, Dong-Kie Kim, Sae-Am Song, Min Ji Kang, and Jae Gyun Shin (Inje University Haeundae Paik Hospital);
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All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases