Effect of antibiotic use on bacterial flora of tonsil core in patients with recurrent tonsillitis

The aim of this study was to investigate the effects of commonly used antibiotics on bacterial flora of the tonsil core. Patients who underwent tonsillectomy for recurrent chronic tonsillitis were included in the study. Three groups were formed: group 1 was treated for 10 days preoperatively with amoxicillin/clavulanic acid; group 2 was treated for 10 days preoperatively with clarithromycin; and group 3 included patients who underwent tonsillectomy without preoperative antibiotic use. The removed palatine tonsils were sent to our microbiology department in sterile tubes for bacteriological analysis. Seventy-three patients (group 1 = 19, group 2 = 20, group 3 = 34 patients) aged 3–18 years (mean 7 years) were included in the study. At least one bacterium was isolated from all tonsils, except for two cases in group 1; the difference in single bacterial growth among groups was not significant (p = 0.06). On the other hand, the numbers of patients with pathogenic bacterial growth was significantly lower in group 2 (n = 2) compared with group 1 (n = 10) and group 3 (n = 27) (p < 0.001). The bacterium isolated most frequently from the tonsils was Streptococcus viridans. Pseudomonas aeruginosa was the only pathogenic bacterium that grew in all three groups. Clarithromycin was more effective than amoxicillin/clavulanic acid in eradicating pathogenic bacteria in the tonsil core. Pseudomonas aeruginosa might be responsible for resistant or recurrent tonsil infections. To prevent endocarditis, antibiotic prophylaxis toward S. viridians, which is the most prevalent bacterium in the tonsil core, should be kept in mind for patients with heart valve damage.