en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <b><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">Introduction</span></span></span></b><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">: <i>Streptococcus pyogenes</i> remains a significant human pathogen responsible for a spectrum of infections, including severe invasive diseases such as streptococcal toxic shock syndrome, and serious post-infectious sequelae like acute rheumatic fever and glomerulonephritis. Considering the recognized antimicrobial properties of <i>Capsicum annuum</i> L. (<i>C. annuum</i> L.) and the persistent clinical challenge presented by <i>S. pyogenes</i>, this study investigated the <i>in vitro</i> antimicrobial activity of an aqueous extract of <i>Capsicum annuum</i> L., Capsaicin (C₁₈H₂₇NO₃), amoxicillin, and a combination of Capsaicin with amoxicillin against <i>S. pyogenes</i> (ATCC 19615). The primary objective was to evaluate both the inhibitory and bactericidal effects of these agents, specifically exploring the potential for synergistic or additive interactions between a plant-derived compound and a conventional antibiotic to improve therapeutic potential. <b>Methods</b>: The antimicrobial activities were evaluated using broth microdilution to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Time-kill kinetics were assessed spectrophotometrically by monitoring bacterial growth. Additionally, disk diffusion assays were performed to evaluate antimicrobial susceptibility. Statistical analyses were conducted using one-way analysis of variance (ANOVA), followed by Tukey&rsquo;s post hoc test to determine significant differences between treatment groups. <b>Results</b>: The aqueous extract of <i>C. annuum</i> L. and Capsaicin both demonstrated significant <i>in vitro</i> inhibitory and bactericidal activity against <i>S. pyogenes</i>. Specifically, MIC and MBC of the aqueous extract were determined to be 12 mg/mL and 14 mg/mL, respectively. For Capsaicin, the MIC was 15 &mu;g/mL, and the MBC was 20 &mu;g/mL. Consistent with these findings, disk diffusion assays revealed distinct zones of inhibition for both agents. Notably, the combination of Capsaicin with amoxicillin exhibited enhanced antimicrobial activity, resulting in a statistically significant reduction in the MIC (<i>P</i> < 0.05) and MBC (<i>P</i> < 0.01) compared to each agent alone. <b>Conclusion</b>: The combination of Capsaicin with amoxicillin demonstrated enhanced bactericidal efficacy in a dose-dependent manner. Notably, Capsaicin exhibited bactericidal activity at microgram concentrations, whereas amoxicillin required milligram concentrations to achieve a comparable effect, highlighting the potent antibacterial properties of Capsaicin. These findings suggest that both the aqueous extract of <i>C. annuum</i> L. and Capsaicin hold significant potential as promising candidates for the development of novel antimicrobial therapies against <i>S. pyogenes</i>.</span></span></span><br> &nbsp; Capsicum annuum L., Streptococcus pyogenes, Capsaicin, Minimum inhibitory concentration, Minimum bactericidal concentration, Disk diffusion assay 259 269 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-598-1&slc_lang=en&sid=1 Azadeh Notashfard azadeh_notash.fard@yahoo.com 0009-0002-3253-0471 Yes Urmia Azad University, Science department, West Azerbaijan, Urmia, zip code: 57169-63896, Iran Majid Nojavan Asghari 0009-0000-6472-249x No Urmia Azad University, Science department, West Azerbaijan, Urmia, zip code: 57169-63896, Iran