Judul: Identification and Susceptibility Test of Escherichia coli Bacteria from Horses to Several Antibiotics
Abstrak: Escherichia coli merupakan mikroflora normal yang terdapat pada saluran cerna. E. coli seiring perkembangan waktu memiliki kemampuan resistan terhadap antibiotik tertentu dan dapat menyebarkan gen resistan ke bakteri lain. Permasalahan resistensi antibiotika merupakan masalah global. Informasi mengenai resistansi terhadap antibiotik pada kuda di Indonesia belum banyak dilakukan. Penelitian ini bertujuan mengidentifikasi bakteri yang ditemukan di saluran cerna pada kuda dan uji resistansi untuk mengetahui pola resistansi bakteri E. coli terhadap antibiotik yang dapat menunjang pengobatan pada kuda. Tahapan penelitian diawali dengan mengisolasi bakteri pada feses kuda menggunakan media agar EMBA dan MCA, lalu diidentifikasi dengan uji pewarnaan Gram serta beberapa uji biokimia. Isolasi dan identifikasi bakteri didapatkan 18 isolat bakteri E. coli, kemudian uji terhadap 6 antibiotik menunjukkan hasil masih peka atau sensitif terhadap antibiotik kloramfenikol (94%), amoksisilin (89%), gentamisin (83%), asam nalidiksat (78%), dan oksitetrasiklin (50%). Isolat resistan terhadap antibiotik sefotaksim (100%)., Escherichia coli is a normal microflora found in the digestive tract. Over time, E. coli can be resistant to certain antibiotics and can spread resistance genes to other bacteria. Overcoming antibiotic resistance is a global problem. Information regarding resistance to antibiotics in horses in Indonesia has not been widely carried out. This study aims to identify the bacteria found in the digestive tract of horses and test the resistance to determine the pattern of resistance of E. coli bacteria to antibiotics that can support treatment in horses. The research phase began with the isolation of bacteria from horse feces using EMBA and MCA agar media, then identified by Gram staining tests and several biochemical tests. Bacterial isolation and assistance obtained 18 isolates of E. coli bacteria, then tests on 6 antibiotics showed the results were still sensitive to the antibiotics chloramphenicol (94%), amoxicillin (89%), gentamicin (83%), nalidixic acid (78%), and oxytetracycline (50%). The isolates were resistant to cefotaxime (100%).
Keyword: antibiotic, Escherichia coli, horse, resistance

Judul: Identification and Sensitivity Test of Salmonella sp. Bacteria in Horses (Equus caballus) to Several Antibiotics.
Abstrak: Kuda memainkan peran yang semakin penting dalam kehidupan manusia. Sistem pencernaan kuda mengandung berbagai jenis bakteri, seperti Salmonella sp. , dan dianggap sebagai salah satu penyebab utama penyakit zoonosis. Tujuan dari penelitian ini adalah untuk mengisolasi dan mengidentifikasi bakteri Salmonella sp. dalam tinja kuda, serta menguji sensitivitas bakteri Salmonella sp. terhadap beberapa antibiotik. Metode penelitian yang digunakan terdiri dari koleksi 20 sampel, isolasi dan identifikasi bakteri, serta pengujian sensitivitas bakteri terhadap antibiotik menggunakan metode difusi cakram atau metode Kirby Bauer. Hasil identifikasi menunjukkan bahwa 9 isolat Salmonella sp. ditemukan dari 20 sampel tinja kuda. Hasil uji sensitivitas bakteri Salmonella terhadap antibiotik yang digunakan menunjukkan bahwa 89% isolat sensitif terhadap gentamisin dan kloramfenikol, 55% terhadap asam nalidiksik, 44% terhadap amoksisilin dan oksitetrasiklin. Hasil intermediat ditemukan untuk beberapa jenis antibiotik seperti amoksisilin (22%), oksitetrasiklin (11%), asam nalidiksik (22%), dan kloramfenikol (11%), sedangkan Salmonella menunjukkan resistansi 100% terhadap sefotaksim. Penelitian ini dapat disimpulkan bahwa Salmonella sp. yang terdeteksi dalam tinja kuda menunjukkan resistansi terhadap sefotaksim namun masih sensitif terhadap amoksisilin, gentamisin, asam nalidiksik, oksitetrasiklin, dan kloramfenikol., Horses play an increasingly important role in human life. The digestive system of horses contains various types of bacteria, such as Salmonella sp. and is considered one of the main causes of zoonotic diseases. The aim of this study was to isolat and identify Salmonella sp. bacteria in horse feces, as well as to test the sensitivity of Salmonella sp. bacteria to several antibiotics. The research method used consisted of collecting 20 samples, isolating and identifying the bacteria, and testing the sensitivity of the bacteria to antibiotics using the disk diffusion or Kirby Bauer method. The identification results showed that 9 isolats of Salmonella sp. were found out of 20 horse feces samples. The results of the bacterial sensitivity test on horses to the antibiotics used showed that 89% of the isolats were sensitive to gentamicin and chloramphenicol, 55% to nalidixic acid, 44% to amoxicillin and oxytetracycline. Intermediate results were found for some types of antibiotics such as amoxicillin (22%), oxytetracycline (11%), nalidixic acid (22%), and chloramphenicol (11%), while Salmonella showed 100% resistance to cefotaxime. This study can be concluded that Salmonella sp. detected in horse feces has shown resistance to cefotaxime but is still sensitive to amoxicillin, gentamicin, nalidixic acid, oxytetracycline, and chloramphenicol
Keyword: Antibiotic resistance, Identification, Horses, Salmonella sp.

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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