The book describes the Phenotypic and Genotypic study of the Bacteroidetes (Bacteroides) in the gut flora of Lean and Obese Patients. It covers description of two types of patient viz. Lean and Obese which have maximum percentage of infections. The present work deals with the field of Medical Science especially Medical Microbiology, Microbial Genetics and Pathology. The publication will be helpful in the systematic study of other types of patients infected from other Bacterial diseases. It will also serve as a reference book to all the people who engaged in the research related to medical field both at national and international level.