A Case Report of Acute Pharyngotonsillitis with Penicillin Treatment Failure in Multidrug-Resistant Streptococcus pyogenes

Background: Streptococcus pyogenes is universally susceptible to beta-lactam antibiotics such as penicillin. However, emerging reports of resistance have raised significant clinical and public health concerns. Case Presentation: We report the isolation of a multidrug resistant Streptococcus pyogenes from a five-year- old boy who presented with clinical symptoms of acute pharyngotonsillitis and a poor clinical response to intramuscular (IM) penicillin G. The bacterium was identified using standard conventional microbiological techniques. Antimicrobial susceptibility testing (AST) was conducted using modified Kirby-Bauer disk diffusion method. The Streptococcus pyogenes isolate was resistant to penicillin G, azithromycin, erythromycin, ceftriaxone and cefotaxime; though susceptible to clindamycin, meropenem and levofloxacin. The multidrug resistant pattern was unexpected, given the organism's known susceptibility profile, which highlights the need for routine AST even in organisms previously considered susceptible. Conclusion: This case highlights the identification of a rare, emerging, and clinically significant resistance pattern in Streptococcus pyogenes, emphasizing the importance of routine susceptibility testing, particularly when treatment failure or atypical clinical progression occurs.