The nature of microbial involvement in the development of adenotonsillar disease

Abstract

Adenotonsillar hyperplasia causes much morbidity in the paediatric population. Before the introduction of antibiotics, adenotonsillar hyperplasia was regarded as an infective process, and only children who met the criteria for a certain number of infective episodes would progress to adenotonsillectomy. Since the early 1970s, there has been an emergence of children presenting with sleep disordered breathing symptoms caused by adenotonsillar hyperplasia. These symptoms have increased in incidence and now represent the most common indication for children who undergo adenotonsillectomy. Our understanding of the pathogenesis around sleep-disordered breathing as it relates to adenotonsillar hyperplasia remains very limited. Arguably the most significant limitation to a better comprehension of the pathogenesis of adenotonsillar hyperplasia is the efficacy of adenotonsillectomy. Because this curative treatment option is readily available, irrespective of the indication for surgery, there is less impetus to explore the pathophysiology underlying the changing indications for adenotonsillectomy. Yet, children do not immediately progress to adenotonsillectomy and in most cases are prescribed multiple courses of antibiotics before surgery even though this may not be warranted in children without infective symptoms. Knowledge of the microbiome in adenotonsillar hyperplasia as it pertains to both infective and sleep-disordered symptoms is limited, and until recently all available information was based on culture studies. These target only a few bacterial groups, and so provide an incomplete assessment of the microbiome. The studies in this thesis used culture independent molecular surveys based on 16S rRNA sequencing to determine the microbiota of adenotonsillar hyperplasia. The results were interpreted according to the child’s presenting symptoms and indications for surgery, and the effect of systemic and topical antibiotics on the microbiome of children with adenotonsillar hyperplasia was investigated. The microbiome of peritonsillar abscess was also examined within the scope of this thesis. This thesis presents some novel observations on the microbiome in children with adenotonsillar hyperplasia. It investigates the efficacy of commonly prescribed systemic and topical antibacterial agents on the disease process. It also challenges on microbiological grounds the assertion that peritonsillar abscess is a complication of recurrent tonsillar infection.