<![CDATA[Urinary tract infections are caused by microorganisms such as Proteus vulgaris bacteria, which are often identified in cases of complicated urinary tract infections. Inappropriate use of antibiotics can lead to resistance, so alternative plant-based treatments are needed. Cherry leaves (Muntingia calabura L.) contain flavonoids, tannins, and saponins that have antibacterial properties. The purpose of this study was to evaluate the antibacterial activity of cherry leaf extract against Proteus vulgaris bacteria and determine its effective concentration. The method used was an antibacterial sensitivity test with the Kirby-Bauer disc diffusion technique, using extract concentrations of 20%, 40%, and 80%, with ciprofloxacin as a positive control and distilled water as a negative control. Furthermore, the inhibition zones formed were measured and comparisons were made between groups using the One Way ANOVA test and the Bonferroni test as a Post Hoc test. The analysis results showed that the diameter of the inhibition zone for each group was 20% = 13 mm, 40% = 15.8 mm, and 80% = 19.8 mm. All of these are still classified as resistant. In conclusion, cherry leaf extract has antibacterial activity against Proteus vulgaris bacteria, but it is not optimal because it is still in the resistant category.Keywords: Muntingia calabura; antibacterial; sensitivity test; Proteus vulgaris; inhibition zone ABSTRAK Infeksi saluran kemih disebabkan oleh mikroorganisme seperti bakteri Proteus vulgaris yang kerap teridentifikasi dalam kasus infeksi saluran kemih berkomplikasi. Penggunaan antibiotik yang tidak tepat dapat menimbulkan resistensi, sehingga alternatif pengobatan berbasis tanaman diperlukan. Daun kersen (Muntingia calabura L.) mengandung flavonoid, tanin, dan saponin yang memiliki sifat antibakteri. Tujuan penelitian ini adalah mengevaluasi aktivitas antibakteri ekstrak daun kersen terhadap bakteri Proteus vulgaris dan menentukan konsentrasi efektifnya. Metode yang digunakan adalah uji sensitivitas antibakteri dengan teknik difusi cakram Kirby-Bauer, menggunakan konsentrasi ekstrak 20%, 40%, dan 80%, dengan ciprofloxacin sebagai kontrol positif dan aquadest sebagai kontrol negatif. Selanjutnya, zona hambat yang terbentuk diukur dan dilakukan perbandingan antar kelompok menggunakan uji One Way ANOVA dan uji Bonferroni sebagai Post Hoc test. Hasil analisis menunjukkan bahwa diameter zona hambat untuk masing-masing kelompok adalah 20% = 13 mm, 40% = 15,8 mm dan 80% = 19,8 mm. Semua ini masih tergolong resisten. Sebagai kesimpulannya, ekstrak daun kersen memiliki aktivitas antibakteri terhadap bakteri Proteus vulgaris, tetapi belum optimal karena masih dalam kategori resisten.Kata kunci: Muntingia calabura; antibakteri; uji sensitivitas; Proteus vulgaris; zona hambat]]>
