Chapter 01. History and Scope of Medical Microbiology PDF

CHAPTER 1 INTRODUCTION AND HISTORY Dr. Kavitha M K. Professor & HOD, Dept. of Medical Microbiology, CIHS, Thalassery LEARNING OBJECTIVES The student will be able to:  Define medical microbiology, and list its branches.  List the classification of microorganisms.  Comprehend variou...

CHAPTER 1 INTRODUCTION AND HISTORY Dr. Kavitha M K. Professor & HOD, Dept. of Medical Microbiology, CIHS, Thalassery LEARNING OBJECTIVES The student will be able to:  Define medical microbiology, and list its branches.  List the classification of microorganisms.  Comprehend various personalities and their work in the field of microbiology. INTRODUCTION  Medical microbiology deals with the study of microorganism.  Diagnosis, treatment and prevention of various infectious diseases are possible due to the study of medical microbiology.  There are different branches of medical microbiology dealing with different sections related to human health and disease.  Understanding different kinds of microorganism such as virus, bacteria fungi and parasites is the key to early diagnosis. MEDICAL MICROBIOLOGY  Medical microbiology is the branch of medicine that deals with the study of microorganisms and their role in human health and disease.  Branches: Four branches Branches Role General microbiology General properties of microorganisms: Taxonomy, Morphology, Pathogenesis, Laboratory diagnosis, and treatment for their effective killing Immunology Study immune system, immunological methods for diagnosis of disease Systematic microbiology Study various kinds of microorganism causing infectious disease. Hospital infection control Study control measures to prevent the transmission of healthcare associated infections CLASSIFICATION OF MICROORGANISMS Microorganisms are grouped under both prokaryotes and eukaryotes. Bacteriology Study of bacteria Prokaryotes Primitive nucleus Virology Study of viruses Neither prokaryotes nor eukaryotes Lack the characteristics of living things Except the ability to replicate Mycology Study of fungi Eukaryotes Well defined nucleus Cellular organelles Parasitology Study of parasites Eukaryotes Protozoa and helminths HISTORY Antonie van Leeuwenhoek First scientist who observed bacteria in 1675 Single biconvex lens Magnified x200 ‘Little animalcules’ Invention of the microscope Edward Jenner in 1796 Developed the First vaccine – smallpox vaccine Used cowpox virus to immunize against smallpox Louis Pasteur (1822-1895): Father of Microbiology. His work contributions includes:  Principles of fermentation  Sterilization techniques  Pasteurization of milk  Germ theory of disease  Liquid media concept  Vaccine against anthrax and rabies  Germ theory of disease Theory of pathogenesis Disease cannot be caused by bad air It is produced by the organisms present in the air  Founder of Pasteur institute, Paris Robert Koch (1843-1910): German physician Father of bacteriology His contributions includes:  Solid media for culture of bacteria.  Hanging drop method for testing motility.  Discovered bacteria such as the anthrax bacilli, tubercle bacilli and cholera bacilli. Introduced Staining techniques  Koch’s postulates Microorganism can be accepted as the causative agent of an infectious disease only if four criteria are fulfilled 1. the microorganism should be constantly associated with the lesions of the disease 2. it should be possible to isolate the organism in pure culture from the lesions of the disease 3. the same disease must result when the isolated microorganism is inoculated into a suitable laboratory animal 4. it should be possible to re-isolate the organism in pure culture from the lesions produced in the experimental animals  Exceptions M. leprae and T. pallidum cannot be grown in cultures N. gonorroeae has no animal model Ignaz Semmelweis in 1846 Importance of hand hygiene in healthcare facilities Proposed that improper hand hygiene practice during delivery led to the transmission of infection Joseph Lister (1867):  Father of Antiseptic surgery.  Postulated use of disinfectants to sterilize surgical instruments and cleaning of wounds to prevent postoperative infections. Hans Christian Gram In 1884 Developed Gram stain Method of staining bacteria Make them more visible and differentiable Paul Ehrlich 1854 – 1915 Father of chemotherapy Discovered salvarsan to treat syphilis Alexander Fleming in 1929 Discovered first antibiotic penicillin Ernst Ruska in 1931 Discovery of electron microscope Karry B Mullis: Discovered polymerase chain reaction (PCR). Nobel prize in 1993 Scope of Medical Microbiology Clinical diagnosis Isolation AST Microbiology in Nursing Handling a patient and clinical samples Sterilize instruments Use antiseptics Universal handwashing technique Aseptic procedures Antibiotic sensitivity test  Blood groups Hypersensitivity reaction Antigen antibody reaction Mass immunization programs Biomedical waste management MICROSCOPY  Microscope is a specialized instrument to view microorganisms (Not visible in naked eyes).  List of microscope used in medical biology: 1. Bright-field or light microscope: Forms dark image against brighter background. It consist of- Mechanical parts- Base, C-shaped arm, Mechanical stage. Magnifying Parts- Ocular lens, Objective lens Illuminating parts- Condenser, Iris diaphragm, Light source, Adjustment knobs. Fig. : Bright-field microscope. 2. Dark-field (or dark ground) microscope: Object appears bright against a dark background by using special dark field condenser. Use: Visualize thin bacteria that are not visible by light microscopy. 3. Phase contrast microscope: Visualize unstained living cells by using special condenser and optic disc. Use: Studying microbial motility, determining shape of living cells, detecting microbial internal cellular components. 4. Fluorescence microscope: Uses fluorescence property to generate an image. Required a fluorescent dye stained specimen for visualization. Use: Acridine orange dye to detect parasites like Plasmodium. Auramine phenol is used for the detection of tubercle bacilli. 5. Electron microscope: Uses accelerated electrons as a source of illumination. Use: Study flagella, fimbriae and intracellular structures of a cell in detail.