Co-Authors:
Neeman, R.
Keller, N., Departments of Clin. M. and P., Chalm Sheba Medical Center, Tel-Hashomer Hospital, Jerusalem, Israel
Barzilai, A., Departments of Clin. M. and P., Chalm Sheba Medical Center, Tel-Hashomer Hospital, Jerusalem, Israel
Korenman, Z., Departments of Clin. M. and P., Chalm Sheba Medical Center, Tel-Hashomer Hospital, Jerusalem, Israel
Sela, S., Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
Abstract:
Background. The failure of antibiotic treatment to eradicate group-A streptococci in up to 30% of patients with pharyngotonsillitis is unexplained. Some strains of group-A streptococci can enter respiratory epithelial cells, where they would be inaccessible to antibiotics unable to penetrate the cell membrane, such as penicillins. The fibronectin-binding proteins, F1 and SfbI, are needed for this process. We hypothesised, therefore, that an intracellular reservoir of group-A streptococci could account, at least partly, for failure to eradicate throat carriage, and that the presence of the gene for fibronectin-binding protein (F1) might be linked to the ability of a strain to persist in the throat after therapy. Methods. We investigated the frequency of prtF1-containing strains among 67 patients with pharyngotonsillitis. All patients were clinically cured, although 13 of them continued to carry group-A streptococci in the throat during or after therapy. To distinguish between persisting and recolonising strains, isolates from the 13 patients were serologically tested and compared by polymorphic DNA-amplification technique. Findings. 12 (92%) of the 13 patients with symptomless had prtF1-containing strains in the throat, with 16 (30%) of the 54 patients with eradication (p = 0.0001). Three of the 13 eradication-failure patients were recolonised with strains that differed from the pretreatment strains. Nine of the ten (90%) persisting strains carried prtF1 (p = 0.0009). Interpretation. Our findings suggest that protein-F1-mediated entry to cells is involved in the causative process of the carriage state.