Introduction to Microbiology PDF

INTRODUCTION TO MICROBIOLOGY DR AHMED YOUSIF INTRODUCTION TO MICROBIOLOGY By the end of this lecture the student should be able to • Definition of Microbiology & Properties of micro organisms • Definition and branches of Medical Microbiology • Basic groups of micro organisms • Comparison between...

INTRODUCTION TO MICROBIOLOGY DR AHMED YOUSIF INTRODUCTION TO MICROBIOLOGY By the end of this lecture the student should be able to • Definition of Microbiology & Properties of micro organisms • Definition and branches of Medical Microbiology • Basic groups of micro organisms • Comparison between prokaryote &eukaryote • Kingdoms & Cell Types of Microorganisms • History Of Microbiology And Infection • Important Theories In Microbiology And Infection DEFINITION OF MICROBIOLOGY Microbiology is the science that studies micro-organisms which are too small to be seen with a naked eye. (Microorganisms= microbes). Properties of microorganisms: • Small organisms • Can’t be seen with the naked eye • Microscope is needed & Electron Microscope EM in case of viruses DEFINITION OF MEDICAL MICROBIOLOGY • Medical microbiology is the branch of microbiology that deals with the study of microorganisms that cause infectious diseases in humans, and the role of these microorganisms in human health and disease. • Medical microbiology is a diverse field with many subdisciplines, and it plays a critical role in the diagnosis, treatment, and prevention of infectious diseases in humans. BRANCHES OF MEDICAL MICROBIOLOGY 1. Bacteriology: This branch deals with the study of bacteria and their role in human health and disease. 2. Virology: This branch deals with the study of viruses and their role in human health and disease. 3. Mycology:This branch deals with the study of fungi and their role in human health and disease. 4. Parasitology: This branch deals with the study of parasites and their role in human health and disease. ((protozoa & Helminth (worms)) 5. Immunology:This branch deals with the study of the immune system and its response to infectious agents. BASIC GROUPS OF MICRO ORGANISMS A] MADE OF CELLS: • BACTERIA • FUNGI • PROTOZOA • HELMINTHS (WORMS) Are complex multicellular organisms B] ACELLULAR: • VIRUSES • PRIONS (Proteinaceous Infectious Particles) COMPARISON BETWEEN PROKARYOTIC & EUKARYOTIC CELLS Criteria Prokaryotes Eukaryotes organisms bacteria, (archaea) Typical size Small cells 1–10 µm protozoa,fungi, Helminthes plants, animals Large cells 10–100 µm Organization usually single cells single cells &multicellular organisms DNA circular (usually) linear membrane-bound organelles absent Ribosomes Small – 70S Present (mitochondria, endoplasmic reticulum, Golgi apparatus) Large – 80S Cell division (Replication) Binary fission (simple division) Mitosis(fission or budding) Meiosis KINGDOMS & CELL TYPES OF MICROORGANISMS Kingdom Microorganisms Type of Cells Animalia Helminths Eukaryotic Plantae None Eukaryotic Protista Protozoa Eukaryotic Fungi Fungi Eukaryotic Bacteria Bacteria Prokaryote Viruses Non cellular BACTERIA 1. Unicellular, prokaryotic organisms 2. Has both DNA & RNA 3. Can be aerobic or anaerobic 4. Can be motile or non-motile 5. Can be beneficial or harmful to humans 6. Reproduce by binary fission 7. Can form biofilms VIRUSES 1. Biphasic Non-living particles (outside) , living infectious particles (inside) the body 2. Non cellular (not made of cells) 3. Has either DNA & RNA 4. Require a host cell to replicate (obligate intracellular organisms) 5. Can cause a wide range of diseases in humans, animals, and plants FUNGI 1. Eukaryotic organisms 2. Has both DNA & RNA 3. Can be unicellular (yeast) or multicellular (moulds) 4. Obtain nutrients through absorption 5. Non motile 6. Can be beneficial or harmful to humans 7. Can reproduce by budding or mitosis 8. Can form spores for dispersal PROTOZOA 1. Unicellular, eukaryotic organisms 2. Has both DNA & RNA 3. Can be free-living or parasitic 4. Most are motile 5. Can cause a variety of diseases in humans, including malaria and amoebic dysentery 6. Reproduce by mitosis PRIONS 1. Proteinaceous Infectious Particles 2. No DNA & RNA 3. Can cause degenerative neurological disorders, (spongiform encephalopathies ) such as 1. 2. 3. Creutzfeldt-Jakob disease in humans Mad cow disease in cows Scrapes in sheep 4. Resistant to conventional sterilization methods COMPARISON OF MEDICALLY IMPORTANT ORGANISMS HISTORY OF MICROBIOLOGY AND INFECTION THEORY OF SPONTANEOUS GENERATION • Aristotle proposed that living organisms, arose spontaneously from non-living matter. • Francesco Redi during the 17th century (refuted the theory of spontaneous generation by using covered and uncovered containers for meat ) • Louis Pasteur in the 19th century was able to refute the theory of spontaneous generation by The Swan Neck experiments, and concluded that microorganisms reproduce • http://bcs.whfreeman.com/thelifewire8e/content/cat_010/0304003.html GERM THEORY OF DISEASE Germ theory of disease • This theory proposes that microorganisms are the cause of many diseases. • It is the cornerstone of modern medicine and clinical microbiology, leading to discoveries of antibiotics and many hygienic practices THE KOCH’S POSTULATES • The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals • the suspected organism should be grown in pure culture • Cells from a pure culture of the suspected organism should cause disease in a healthy animal • The organism should be re-isolated and shown to be the same as the original THE KOCH’S POSTULATES • REFERENCES • Review of Medical Microbiology and Immunology 14th Edition