Evaluation of the Combined Antibacterial Activity of Katuk Leaf Extract (Sauropus androgynus (L.) Merr.) and Lemon Juice (Citrus limon L.) against Streptococcus pyogenes as Causative Agent of Pharyngitis

I Gusti Ayu Agung Amelia Prabhawanti (Bachelor of Medicine, Faculty of Medicine, Udayana University, Bali, Indonesia)
Ni Wayan Sucindra Dewi (Department of Pharmacology and Therapy, Faculty of Medicine, Udayana University, Bali, Indonesia)
Desak Ketut Ernawati (Department of Pharmacology and Therapy, Faculty of Medicine, Udayana University, Bali, Indonesia)
Agung Nova Mahendra (Department of Pharmacology and Therapy, Faculty of Medicine, Udayana University, Bali, Indonesia)
Bagus Komang Satriyasa (Department of Pharmacology and Therapy, Faculty of Medicine, Udayana University, Bali, Indonesia)

GANESHA MEDICINA
Vol. 6 No. 1 (2026)

Pharyngitis is an inflammation of the pharynx, one cause of which is the bacterium Streptococcus pyogenes. Although antibiotics are the primary therapy, high rates of resistance necessitate the search for alternative natural-based agents. This study aimed to evaluate the in vitro antibacterial activity of a combination of katuk leaf extract (Sauropus androgynus (L.) Merr.) and lemon juice (Citrus limon L.) against Streptococcus pyogenes. The study was experimental, employing a true experimental design (post-test only with a control group). Antibacterial activity was assessed using the Kirby–Bauer disk diffusion method. The results showed that the combination produced mean inhibition zone diameters of 6.02 mm at 25% concentration, 7.16 mm at 50% concentration, and 7.40 mm at 75% concentration, while the positive control produced a mean inhibition zone of 32 mm. In conclusion, the combination of katuk leaf extract and lemon juice exhibited moderate antibacterial activity against Streptococcus pyogenes and has potential for further development as a natural antibacterial candidate.