Phenotypic Analysis of Antibiotic Resistance Mechanisms in Bacteria Causing Tonsillitis: Focus on ESBL, MBL, and MRSA

Abstract

Introduction: Tonsillitis, a common inflammatory condition primarily affecting children, is caused by various bacterial and viral pathogens. The condition poses a significant public health challenge due to the rise in antimicrobial resistance, especially among methicillin-resistant Staphylococcus aureus (MRSA), Extended Spectrum Beta-Lactamase (ESBL)-producing, and Metallo Beta-Lactamase (MBL)-producing bacteria. This study investigates the prevalence of these resistant bacterial strains in tonsillitis cases to inform effective treatment strategies and improve clinical outcomes.

Methods and Materials: This cross-sectional observational study was conducted at the Krishna Institute of Medical Sciences, India, from November 2021 to November 2022. Throat swab samples from tonsillitis patients were collected and cultured. Confirmed bacterial isolates were tested for antibiotic resistance using phenotypic methods: MRSA was detected using cefoxitin disc diffusion, ESBL production was confirmed with ceftazidime and ceftazidime-clavulanic acid discs, and MBL production was assessed via imipenem-EDTA disc testing. Data were statistically analyzed, and results were expressed as percentages.

Results: Out of 96 bacterial isolates, 58.97% of Staphylococcus aureus isolates were MRSA, 36.53% of gram-negative isolates were ESBL producers, and 46.15% were MBL producers. MRSA isolates were highly susceptible to linezolid and chloramphenicol, while doxycycline and azithromycin showed moderate effectiveness against ESBL and MBL producers. The high prevalence of resistant strains highlights the need for careful antibiotic selection and emphasizes the importance of local resistance data in guiding treatment protocols.

Conclusion: The study reveals a significant prevalence of MRSA, ESBL, and MBL-producing bacteria among tonsillitis-causing pathogens, underscoring the critical need for routine susceptibility testing and antimicrobial stewardship. Effective infection control strategies and continuous surveillance are essential to mitigate the impact of antibiotic resistance, ensuring optimal patient outcomes and public health protection.