Despite
antibiotics being the primary medical treatment for recurrent
tonsillitis, the impact of
antibiotics on the tonsillar microbiome is not well understood. This study aimed to determine the effect of
amoxicillin with
clavulanate on the composition and quantity of bacteria in the tonsils of children with recurrent
tonsillitis. A multicenter randomized clinical trial in Auckland, New Zealand was undertaken between August 1, 2017, and June 30, 2018. Sixty children undergoing
tonsillectomy for the indication of recurrent
tonsillitis were recruited for this study. Following random allocation, 30 participants were prescribed
amoxicillin with
clavulanate for the week before surgery. The remaining 30 received no
antibiotics. Immediately following surgery, the crypts of the right and left tonsils were swabbed. Bacterial
16S rRNA gene-targeted amplicon sequencing and histological techniques were utilized. In the control group, there were significantly higher relative abundances of Haemophilus, Streptococcus, Neisseria, and Porphyromonas. Members from the genera Fusobacterium and Treponema were found to be significantly more abundant in the
antibiotic group. There were no significant differences in the absolute quantities of bacteria between the groups. Microscopic examination found fewer bacterial microcolonies present in the tonsillar crypts of participants in the
antibiotic group. Streptococcus pyogenes was not present in these bacterial microcolonies. These results suggest that a single course of
antibiotics has a significant impact on the tonsil microbiota composition. The duration of this effect and the effect that the altered microbiome has on the course of the condition need to be determined. IMPORTANCE Several studies have identified the presence of multiple pathogenic bacteria in hyperplastic adenoids and palatine tonsils. However, there are currently no studies that utilize this technology to investigate the effect of oral
antibiotics in children with recurrent
tonsillitis on the tonsillar microbiome. This is the first study to investigate the effect of
antibiotics on the microbiome of tonsillar tissue in children with recurrent
tonsillitis using molecular techniques. This study has shown that participants who received
amoxicillin with
clavulanate immediately before
tonsillectomy had a significantly reduced number of bacterial taxa commonly associated with recurrent
tonsillitis, as well as the number of bacterial microcolonies observed in the tonsillar crypts. This novel finding suggests that either the effect of
antibiotics is not sustained or that they are not an effective treatment for recurrent
tonsillitis.