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 Antimicrobial Susceptibility Test of Gram-Positive Catalase-Negative Cocci in Horses (Equus caballus)
Abstrak: Kasus resistansi mikroba terhadap antimikroba sudah banyak terjadi di dunia salah satunya pada kuda. Bakteri coccus Gram positif katalase negatif dapat menjadi bakteri patogen yang menyerang saluran pencernaan kuda. Belum ada penelitian mengenai resistansi bakteri coccus Gram positif katalase negatif pada kuda di Indonesia terhadap berbagai jenis antibiotik. Penelitian dilakukan dengan mengidentifikasi bakteri coccus Gram positif katalase negatif dan menguji kepekaannya terhadap 6 jenis antibiotik dengan metode difusi cakram. Data hasil penelitian dianalisis dan disajikan secara deskriptif melalui perbandingan dengan tabel standar diameter zona hambat atau kepekaan antibiotik Clinical and Laboratory Standards Institute (CLSI) tahun 2021. Hasil identifikasi ditemukan 7 isolat bakteri coccus Gram positif katalase negatif dari dua puluh sampel feses kuda sehat dan dewasa di Jakarta International Equestrian Park. Dari 7 isolat bakteri coccus Gram positif katalase negatif tersebut, 4 isolat teridentifikasi sebagai bakteri Enterococcus sp. sedangkan ketiga lainnya teridentifikasi sebagai bakteri Streptococcus sp. Hasil uji kepekaan bakteri coccus Gram positif katalase negatif menunjukkan isolat bakteri resistan terhadap sefotaksim dan asam nalidiksat. Kepekaan bakteri terhadap amoksisilin, oksitetrasiklin, dan kloramfenikol masih relatif peka. Saran yang dapat disampaikan penulis mengenai penelitian ini yaitu diperlukan adanya penelitian lebih lanjut mengenai faktor ras yang mempengaruhi terjadinya infeksi bakteri. Selain itu, diperlukan identifikasi lebih lanjut berupa identifikasi secara molekuler dengan PCR., Many cases of antimicrobial resistance have occurred in the world, one of which is in horses. Catalase-negative Gram-positive coccus bacteria are pathogenic bacteria that attack the digestive tract of horses. There has been no research on the resistance of Gram positive catalase-negative coccus bacteria in horses in Indonesia to various types of antibiotics. The research was conducted by identifying catalase-negative Gram positive coccus bacteria and testing their sensitivity to 6 types of antibiotics by disc diffusion method. The data were analysed and presented descriptively through comparison with the standard table of inhibition zone diameter or antibiotic sensitivity of the Clinical and Laboratory Standards Institute (CLSI) in 2021. Seven isolates of catalase-negative Gram-positive coccus bacteria were found from twenty faeces samples of healthy and adult horses at the Jakarta International Equestrian Park. Of the seven isolates of catalase-negative Gram positive coccus bacteria, four isolates were identified as Enterococcus sp. while the other three were identified as Streptococcus sp. The results of the sensitivity test of catalase-negative Gram-positive coccus bacteria showed that the bacterial isolates were resistant to cefotaxime and nalidixic acid. Bacterial sensitivity to amoxicillin, oxytetracycline, and chloramphenicol is still relatively sensitive. Suggestions that can be conveyed by the author regarding this research are that further research is required regarding breed factors that affect the occurrence of bacterial infections. In addition, further identification is needed in the form of molecular identification by PCR.
Keyword: Enterococcus, Streptococcus, negative catalase, horse, antimicrobial susceptibility

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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