#57: The Clinical Significance of Changes in the Microbial Communities of the Nasal Cavity in Patients with Solid Tumors of Parameningeal Localization During Radiation Therapy
Authors: Gorbunova Tatyana , Rodina Anastasia , Merculov Oleg , Polyakov Vladimir 
Published: March 2021

Abstract

Background
Immunosuppressive therapy places pediatric patients at risk of developing life-threatening sinonasal infections. Radiation-induced rhinitis is poorly studied and considered in clinical practice. Recognition of the unique microbial cultures of the nasal cavity and their antimicrobial susceptibility is of great importance when selecting antimicrobial therapy. Radiation therapy can affect nasal cavity microbiota. Despite considerable research, the pathogenesis of rhinitis remains poorly understood.

Materials and Methods
The study included 10 patients (boys 6; girls 4). Of them, the number of patients with rhabdomyosarcoma is 6 patients (60%), nasopharyngeal cancer 3 (30%), and hemangiopericytoma 1 (10%). The average age is 12.4 g. The observation period is 9–18 months. Tumors were localized in the nasopharynx 30%, paranasal sinuses on the one hand 50%, and on both sides 20%. Chemotherapy (ChT) included 8–16 courses. Radiation therapy (RT) was carried out after 4–6 courses, SOD 40–50 Gy. Examination of the otorhinolaryngologist and endoscopic examination of the nasal cavity were performed for all patients before and after the completion of special treatment. Standard microbial culture studies are carried out before (T0), in the middle of the course of radiation therapy (RT) (T1), and at the end (T2) RT. A repeat study microbial culture 12 months after completion of RT (T3). An analysis of the results will be compared with clinical data.

Results
All patients showed symptoms of chronic rhinosinusitis before the start of special treatment. Clinically determined: hyperemia and swelling of the mucosa of the lower and middle turbinates in 100% of cases, unilateral mucopurulent and purulent discharge in 70%, and bilateral in 30%. Complications and concomitant pathology were diagnosed in the form of dysfunction of the auditory tube in 30%, signs of tubo otitis in 60%, unilateral catarrhal otitis media in 10% of cases. During the bacteriological examination of a nasal swab against the background of chemotherapy, bacteria of the family Staphylococcaceae and Streptococcaceae with the same purity of 30%, fungi of the genus Candida in 20%, H. parainfluenzae and Corynebacterium amycolatum were equally divided in 10% of cases. Symptoms of exacerbation of chronic inflammation were detected in 100% of patients after 18–24 Gy was added to the tumor. After 3 months the completion treatment, gram-negative bacteria were obtained in smears: Enterobacter cloacae in 30%, Pseudomonas aeruginosa in 20%, Acinetobacter species in 10%, and mixed flora (Staphylococcus haemolyticus and Staphylococcus haemolyticus MRS), in 10% of patients.

Conclusion
Clinical manifestations of chronic rhinosinusitis accompany the growth of malignant tumors of the nasopharynx and paranasal sinuses. An increase in the concentration of pathogenic and conditionally pathogenic bacteria in the nasal cavity during CRT reflects a decrease in nonspecific immunity and the general immune resistance of the body.