Staphylococcus aureus merupakan bakteri patogen penyebab infeksi kulit hingga pneumonia. Keberadaan S. aureus dengan sifat resistan antibiotik atau disebut sebagai Methicillin-Resistant Staohylococcus aureus (MRSA) menjadi salah satu masalah kesehatan dunia. Sifat resisten antibiotik pada S. aureus dimediasi oleh dua gen, yaitu yaitu mecA dan femA. Bakteri MRSA dapat menyebar di lingkungan, salah satunya melalui sungai. Isolasi dari sampel air sungai dilakukan menggunakan metode membrane filtration yang ditumbuhkan pada medium selektif mannitol salt agar (MSA). Koloni tunggal yang memiliki warna kuning serta berhasil merubah warna medium dipilih untuk analisis lebih lanjut secara molekuler. Pendeteksian molekuler menggunakan gen STPY (257 bp), mecA (297 bp), dan femA (454 bp) dilakukan untuk memastikan spesies S. aureus dan keberadaan gen resistan. Hasil penelitian berhasil mengisolasi 16 isolat yang melalui uji molekuler didapatkan bahwa 12 di antaranya merupakan MRSA karena positif gen STPY, mecA, dan femA, atau kombinasi keduanya. Sedangkan 4 isolat lainnya terdeteksi sebagai Methicillin Resitant Stapylococcus non-aureus (MRnSA) karena tidak memiliki gen STPY, tetapi menujukkan keberadaan gen 16S rRNA Universal dan gen resistan. Empat isolat tersebut kemudian melalu tahapan sequencing dan terdeteksi sebagai S. gallinarum dan S. sciuri. Penemuan MRSA di sungai menujukkan adanya potensi penyebaran MRSA yang mendukung perluasan pemahaman mengenai keberadaan bakteri resistan antibiotik di lingkungan yang berpotensi membahayakan kesehatan masyarakat.

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Staphylococcus aureus is a pathogenic bacterium that causes skin infections and pneumonia. The existence of S. aureus with antibiotic-resistant properties or referred as Methicillin-Resistant Staohylococcus aureus (MRSA) is one of the world's health problems. The antibiotic-resistant nature of S. aureus is mediated by two genes, mecA and femA. MRSA bacteria can spread in the environment, one of which is through rivers. Isolation from river water samples was carried out using the membrane filtration method grown on selective mannitol salt agar (MSA). Single colonies that had a yellow color and changed the color of the medium were selected for molecular analysis. Molecular detection using the STPY (257 bp), mecA (297 bp), and femA (454 bp) genes was performed to confirm S. aureus species and the presence of resistance genes. The results of the study successfully isolated 16 isolates which through molecular testing found that 12 were MRSA because they were positive for the STPY, mecA, and femA genes, or a combination of both. While the other 4 isolates were detected as Methicillin Resitant Stapylococcus non-aureus (MRnSA) because they did not have the STPY gene, but showed the presence of the Universal 16S rRNA gene and the resistance gene. The four isolates then went through sequencing and were detected as S. gallinarum and S. sciuri. The discovery of MRSA in the river indicates the potential spread of MRSA which supports the expansion of understanding of the presence of antibiotic-resistant bacteria in the environment that could potentially endanger public health.