This book is structured and designed so as to meet the needs of students of PG Microbiology , Medicine, dentistry and pharmacy students. The authors made an attempt to present the basic concepts and recent aspects encompassing the important bacterial, fungal, viral and protozoan diseases in a lucid way to the student community and teaching fraternity. The opening chapter presents an overview of the foundations of Microbiology. The next chapter incorporates important bacterial diseases that are more prevalent in the present situation. The third chapter deals with the major fungal diseases including superficial, systemic and opportunistic fungal diseases. A detailed account of mycotoxins and mycotoxicoses is also included. The sixth chapter is devoted to significant viral diseases along with the recent pandemic COVID-19. Important protozoan diseases are covered in the sixth chapter. Lastly a complete coverage of antibiotics is furnished along with their mode of action. The authors made an attempt to incorporate the latest research findings, newer diagnostic techniques and novel drugs available to treat the dreadful diseases. About the Author: Dr. Kandru Ammani is a retired Professor in the Department of Botany and Microbiology, Acharya Nagarjuna University, A.P. India. Spent over 38 years of research and 32 years of teaching in various fields of Botany and Microbiology. Successfully guided 15 Ph.D.'s &10 M.Phil.'s in different fields of Botany, Biotechnology, Microbiology, Biochemistry and Food Nutrition and currently supervising 12 students for their degrees. Recipient of FBS by Indian BotanicalSociety (2013) and International EAES Award of Excellence in Environmental Microbiology in 2014. Received the “Best Teacher”award by Govt.of Andhra Pradesh (2019) and “National Award of Excellence” fromGlobal Management Council, Ahmedabad (2016) and “Woman of Excellence” in2016. During 2017, chosen as Indian Icon for the commendable achievement in the field of education and teaching.Honored with Distinguished Scientist award (2019) by Academy of Plant Sciences, India and APSI GoldMedal (2017) for her specialized field of research. Recognized her for Best Research Publications during the Foundation Day Celebrations of Acharya Nagarjuna University for about 6 times. Organized workshops on Patenting and Nanotechnology. Authored and co-authored over 90technical papers in renowned International and National journals and presented more than 200 research papers in National and International conferences in India, USA, UAE, Sri Lanka, Nepal, Dubai & Malaysia. Delivered a keynote speech at an International Conference of Advances in Biotechnology held in Malaysia & Dubai, UAE(2019&2017). Invited talks delivered at International Conference in Nepal(2014) SriLanka (2013) and at John Hopkin's University, Maryland, USA(2012) and Chaired the Conference Topic Sessions. Contributed several chapters in reputed books. Member/Life Member of more than 20 reputed prestigious institutes and professional associations such as Asian PGPR Society for Sustainable Agriculture, ASM, AMI, ABAP,BRSI, EAES, ISCA, IANCAS, ISRS, IBS, SBA, SBTI etc. and Fellow Member in Professional Associations of Botany, Biotechnology & Environmental Sciences. Editorial board member for about nine well recognized journals and reviewer for various high impact National & International Journals. Proud member of “Inner wheel” which is an International world's largest women service voluntary organization. Dr. Raghava Kalyan, Presently working as Assistant Professor in the department of Pharmacy practice, CHIPS, Guntur. completed his Pharm.D at JSS, Mysore, a prestigious institute of Pharmacy. He is an excellent writer, voracious reader and an exemplary orator. Also he is the clinical pharmacist at NRI hospital, Chinakakkani. He has organized and participated in several seminars and webinars. He Pulished review articles in Elseveir and in Cambridge Scholars Publishing.