Background: Recurrent tonsillitis is one of the most common diseases in childhood, caused many times by ß-lactam-resistant S. aureus. The objective of this study was to investigate an alternative method to identify resistance to oxacillin/cefoxitin in S. aureus from hospitalized children with recurrent tonsillitis. Methods: The samples of S. aureus came from patients with recurrent tonsillitis and were used in 16S rRNA sequencing and an antibiogram test for identification and verifying resistance, after which HSI methodology were applied for separation of S. aureus resistances. Results: The S. aureus isolated showed sensitivity to oxacillin/cefoxitin and the diagnostic images show a visual description of the resistance different groups formed, that may be related to sensitivity and resistance to oxacillin/cefoxitin, characterizing the MRSA S. aureus. Conclusions: Samples that showed phenotypic resistance to oxacillin/cefoxitin were clearly separated from samples that did not show this resistance. A PLS-DA model predicted the presence of resistance to oxacillin/cefoxitin in S. aureus samples and it was possible to observe the pixels classified as MRSA. The HSI was able to successfully discriminate samples in replicas that were sensitive and resistant, based on the calibration model it received.

To analyze the profile of airway Upper Respiratory Tract isolates from children with recurrent tonsillitis. Samples were taken using nasal cavity, oropharynx and nasopharynx swabs from30 children called the test group before tonsillectomy. Counting, isolation, identification and sequencing of the 16S rRNA, biofilm production and antimicrobial sensitivity investigation were performed. Staphylococcus aureus (S. aureus) was the only microorganism recovered in 36.6% of patients, being more present in the oropharynx and with greater resistance to erythromycin 95%, penicillin 85% and cefoxitin 85%. All isolates were formed by biofilm, 20% formed by strongly adherent biofilm. S. aureus resistant and biofilm formed, were isolated in the three studied sites, suggesting that this species contributes to recurrent tonsillitis. Impact of the study: The ability of S. aureus to acquire resistance and its other associated factors such as biofilm formation, can make this microorganism recover more easily in the microbiota of patients, taking into account the other microorganisms present there after the use of antibacterial.