Judul: Identification of Gram Negative Bacteria and E. coli Antimicrobial Susceptibility Test on Sumatran Orang Utan in Taman Nasional Gunung Leuser
Abstrak: Orang utan merupakan satwa endemik Indonesia yang keberadaannya terancam punah. Salah satu penyakit yang sering menginfeksi orang utan liar adalah penyakit pencernaan yang disebabkan oleh bakteri patogen yang tergolong bakteri Gram negatif. Penyakit infeksi yang disebabkan oleh bakteri dapat diobati dengan antibiotik, namun penggunaannya terkadang kurang efektif karena resistansi antibiotik. Identifikasi bakteri Gram negatif dan uji kepekaan antibiotik pada studi ini perlu dilakukan untuk mengetahui bakteri yang terkandung dalam feses orang utan serta mengetahui antibiotik yang masih sensitif dan yang telah resistan terhadap bakteri Escherichia coli. Bakteri pada feses orang utan diisolasi pada media agar EMBA dan MCA dan diidentifikasi menggunakan uji pewarnaan Gram dan beberapa uji biokimia, mulai dari uji oksidase, uji fermentasi karbohidrat, uji urea, uji TSIA, uji motilitas dan uji IMViC. Uji kepekaan antibiotik dilakukan dengan uji difusi dengan metode Kirby Bauer terhadap 12 antibiotik. Hasil dari identifikasi bakteri Gram negatif ditemukan bakteri Yersinia sp., Citrobacter sp., Escherichia coli, Escherichia vulneris, Klebsiella spp., Stenotrophomonas maltophilia, dan Kluyvera sp.. Isolat bakteri Escherichia coli yang diuji terhadap 12 antibiotik menunjukkan hasil masih peka atau sensitif terhadap antibiotik amoksisilin, tetrasiklin, oksitetrasiklin, doksisiklin, gentamisin, streptomisin, kloramfenikol, siprofloksasin, asam nalidiksat, dan enrofloksasin., Orang utans are Indonesian’s endemic animal which are threatened by extinction. One of the diseases that often infects wild orang utans is digestive disease caused by pathogenic bacteria belonging to Gram-negative bacteria. Infectious diseases caused by bacteria can be treated with antibiotics, but the usage is less effective from time to time because of antibiotic resistancy. Identification of Gram negative bacteria and antibiotic susceptibility tests in this study need to be carried out to determine the bacteria contained in orang utan feces and antibiotics that are still susceptible to Escherichia coli bacteria. Bacteria in orang utan feces were isolated on EMBA and MCA agar media and identified using Gram stain test and several biochemical tests, starting from the oxidase test, carbohydrate fermentation test, urea test, TSIA test, motility test and IMViC test. Antibiotic susceptibility test was carried out by diffusion test using the Kirby Bauer method on 12 antibiotics. The results of the identification of Gram-negative bacteria were Yersinia sp., Citrobacter sp., Escherichia coli, Escherichia vulneris, Klebsiella spp., Stenotrophomonas maltophilia, and Kluyvera sp.. The isolate of Escherichia coli bacteria tested against 12 antibiotics showed that it were susceptible to amoxicillin, tetracycline, oxytetracycline, doxycycline, gentamycin, streptomycin, chloramphenicol, ciprofloxcacin, nalidixid acid, and enrofloxacin.
Keyword: bakteri Gram negatif, Escherichia coli, orang utan liar, kepekaan antibiotik

Judul: Resistance Test of Escherichia coli Pathogen from  Feces Sample of Bornean Orangutan (Pongo pygmaeus) at Taman Safari Indonesia-Bogor
Abstrak: Orang utan merupakan salah satu primata dan satu-satunya kera besar yang hidup di Asia. Gangguan saluran pencernaan pada orang utan biasanya berupa diare yang disebabkan oleh bakteri enteropatogen E. coli. Pengobatan dengan antibiotik pada orang utan harus mempertimbangkan sensitivitas bakteri terhadap antibiotik. Penelitian ini bertujuan mengetahui gambaran resistansi Escherichia coli patogen pada sampel feses orangutan kalimantan (Pongo pygmaeus) di Taman Safari Indonesia – Bogor terhadap beberapa antibiotik. Sebanyak 10 sampel diisolasi dan diidentifikasi keberadaan E. coli patogen dan sebanyak 10 isolat terdeteksi sebagai E. coli patogen. Uji resistansi dilakukan dengan metode Kirby-Baurer Disk Diffusion Test menggunakan 7 antibiotik yang berbeda. Hasil uji menunjukkan 20% isolat telah resistan terhadap tetrasiklin, 30% isolat resistan terhadap antibiotik streptomisin, trimetoprim dan trimetoprim-sulfametoksazol, dan 90% telah resistan terhadap ampisilin. Sementara itu 100% isolat sensitif terhadap kloramfenikol, 70% sensitif terhadap trimetoprim dan trimetoprim-sulfametoksazol, serta 50% sensitif terhadap siprofloksasin. Antibiotik yang menunjukkan hasil resistan tidak direkomendasikan untuk pengobatan infeksi oleh E. coli pada orang utan., Orangutans are one of the primates and the only great apes which live in Asia. Gastrointestinal problem in orangutans usually characterized by diarrhea which comes from enteropathogenic bacteria E. coli. Moreover, treatment with antibiotics in orangutans should take into account the sensitivity of the bacteria to antibiotics. The aim of this study is to describe the resistance of pathogenic Escherichia coli in fecal samples of the Bornean orangutan (Pongo pygmaeus) at Taman Safari Indonesia – Bogor to several antibiotics. A total of 10 samples were isolated and identified the presence of pathogenic E. coli and as many as 10 isolates were detected as pathogenic E. coli. Moreover, the resistance test was conducted by using the Kirby-Bauer Disk Diffusion Test method using 7 different antibiotics. The test results show that 20% of the isolates were resistant to tetracycline, 30% of the isolates were resistant to the antibiotics streptomycin, trimethoprim and trimethoprim-sulfamethoxazole, and 90% were resistant to ampicillin. Meanwhile, 100% of isolates were sensitive to chloramphenicol, 70% sensitive to trimethoprim and trimethoprim-sulfamethoxazole, and 50% sensitive to ciprofloxacin. Antibiotics that show resistance are not recommended for the treatment of infections by Escherichia coli in orangutans.
Keyword: antibiotic, Escherichia coli, orangutan, resistance

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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