1. Universitas Sumatera Utara, Medan, Indonesia Department of Internal Medicine, Universitas Prima Indonesia, Medan, Indonesia
2. Department of Pharmacology and Therapeutics, Universitas Sumatera Utara, Medan, Indonesia
3. Department of Biology, Universitas Sumatera Utara, Medan, Indonesia
4. Department of Microbiology, Universitas Sumatera Utara, H. Adam Malik General Hospital, Medan, Indonesia