<![CDATA[Abstract. Streptococcus pyogenes is a major human pathogen causing a broad spectrum of clinical illnesses from mild ones such as pharyngitis and skin infections, to more severe diseases such as sepsis, streptococcal toxic shock syndrome, post-streptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. It has reported the failure of ampicillin therapy against S. pyogenes. Therefore, new antibacterial agents with high potency are needed. One of the plants that empirically have antibacterial activity is robusta coffee. Roasted robusta coffee bean extract (Coffea canephora) contains several antibacterial agents. Such as chlorogenic acid, flavonoids, trigonelline, caffeine and hydrogen peroxide (H2O2). The purpose of the study was to determine the comparison of the inhibitory effect of robusta coffee extract and ampicillin in agar media culture of Streptococcus pyogenes. The method used was Kirby-Bauer disc diffusion which consisted of treatment groups with 100%, 50%, 25%, and 12.5% concentrations of robusta coffee extract, a positive control group (ampicillin 10 µg) and a negative control group (aquadest). The results showed that the average value of the largest inhibition zone was found in the positive control of ampicillin which was 38.49 mm (very sensitive), followed by 100% coffee extract was 15.24 mm (sensitive), 50% coffee extract was 11.38 mm (moderately sensitive), and 25% coffee extract was 8.13 mm (moderately sensitive). Robusta coffee extract 12.5% did not form an inhibition zone, similar to aquadest as a negative control. In conclusion, 100%, 50%, 25%, and 12,5% robusta coffee extract has a good inhibitory effect against the growth of Streptococcus pyogenes bacteria but is still lower than ampicillin. Abstrak. Streptococcus pyogenes adalah patogen penting pada manusia sebagai penyebab penyakit dengan spektrum klinis luas, mulai dari yang ringan seperti faringitis dan infeksi kulit hingga yang berat seperti sepsis, sindrom syok toksik streptokokus, glomerulonefritis akut pasca streptokokus, demam rematik akut, dan penyakit jantung rematik. Kegagalan terapi ampisilin terhadap S. pyogenes telah banyak dilaporkan, sehingga diperlukan produk antibakteri baru yang memiliki potensi tinggi. Salah satu tanaman yang secara empiris memiliki aktivitas antibakteri adalah kopi robusta. Ekstrak biji kopi robusta (Coffea canephora) yang telah dipanggang mengandung berbagai zat antibakteri seperti asam klorogenat, flavonoid, trigonelin, kafein, dan hydrogen peroksida (H2O2). Tujuan penelitian adalah membandingkan daya hambat ekstrak kopi robusta dengan ampisilin terhadap kultur bakteri Streptococcus pyogenes. Metode yang digunakan adalah difusi cakram Kirby-Bauer yang terdiri dari kelompok perlakuan ekstrak kopi robusta konsentrasi 100%, 50%, 25%, dan 12,5%, kelompok kontrol positif (ampisilin 10 µg) dan kontrol negatif (akuades). Hasil nilai rerata zona hambat terbesar terdapat pada kontrol positif ampisilin yaitu 38,49 mm (sangat sensitif), kemudian diikuti dengan zona hambat pada ekstrak kopi robusta 100% yaitu 15,24 mm (sensitif), ekstrak kopi robusta 50% yaitu 11,38 mm (cukup sensitif), dan 25% yaitu 8,13 mm (cukup sensitif). Pada ekstrak kopi robusta 12,5% tidak terbentuk zona hambat, setara dengan kontrol negatif. Simpulan: ekstrak kopi robusta 100%, 50%, 25%, dan 12,5% memiliki daya hambat yang baik, namun lebih lemah dibandingkan ampisilin terhadap pertumbuhan bakteri Streptococcus pyogenes.]]>
