Comparative in vitro Activity of Selected Antibiotics and Probiotics against Staphylococcus aureus and Streptococcus pyogenes from Impetigo Cases in Wasit, Iraq

Abstract

Impetigo is a common and contagious superficial skin infection, primarily caused by Staphylococcus aureus and Streptococcus pyogenes. This study aimed to assess the in vitro activity of selected antibiotics and probiotics against S. aureus and S. pyogenes isolated from impetigo cases in Wasit, Iraq, and to compare their antimicrobial effects. In a cross-sectional study conducted from August to November 2024, 102 skin swabs were collected from patients with impetigo. Bacterial isolates were identified using standard microbiological methods and the Vitek® 2 system. Antibiotic susceptibility was determined by the disk diffusion method for 31 S. aureus and 6 S. pyogenes isolates against 17 antibiotics. The inhibitory activity of Lactobacillus rhamnosus and Lactobacillus fermentum was evaluated using the well diffusion and agar spot methods.S. aureus was the predominant pathogen (48.0%), followed by S. pyogenes (5.9%). S. aureus showed high resistance to penicillin G (90.3%) but remained susceptible to levofloxacin (100%) and vancomycin (96.8%). S. pyogenes exhibited 100% susceptibility to penicillin G but high resistance to tetracycline (66.7%). Both probiotic strains demonstrated significant antibacterial activity. L. fermentum showed larger inhibition zones (18 mm against S. aureus, 16 mm against S. pyogenes in the well diffusion method) compared to L. rhamnosus. The agar spot method proved more effective, with inhibition zones reaching up to 26 mm for L. fermentum. The study reveals significant antibiotic resistance among impetigo pathogens in Wasit, Iraq, highlighting the need for updated treatment guidelines. The potent in vitro antimicrobial activity of L. rhamnosus and L. fermentum suggests that probiotics could be a promising alternative or adjunctive therapy for impetigo, warranting further clinical investigation.