Introduction of medical microbiology unit 1

microbiology is vast study of microorganisms

1. INTRODUCTION OF MEDICAL MICROBIOLOGY PRESENTED BY MEGHA SHRIDHAR

2. INDEX DEFINITION HISTORY HOST-MICROBE RELATIONSHIP

3. BACTERIOLOGY Bacteriology is the branch and specialty of biology that studies the morphology, ecology, genetics and biochemistry of bacteria.

4. VIROLOGY Virology is the study of viruses and including their taxonomy, disease-producing properties, cultivation and genetics.

5. PARASITOLOGY Parasitology is the study of parasites, their hosts, and the relationship between them.

6. MYCOLOGY Mycology is the branch of biology concerned with the study of fungi.

7. IMMUNOLOGY Immunology is the study of the immune system. The immune system protects us from infection through various lines of defence.

8. RECOMBINANT DNA TECHNOLOGY Recombinant DNA technology refers to the joining together of DNA molecules from two different species that are inserted into a host organism to produce new genetic combinations.

9. HISTORY

10. ANTONY VAN LEEWANHOEK (1632-1723)

11. LOUIS PASTEUR (1822-1895) (FATHER OF MICROBIOLOGY) Discovered Spontaneous generation theory of microbes. O riginated the process of pasteurization & Fermentation; D eveloped vaccines against anthrax against Smallpox and rabies.

12. SPONTANEOUS GERM THEORY

13. ROBERT KOCH (1843-1910) (FATHER OF BACTERIOLOGY) Experimental approach to prove Germ Theory of Disease, which is known as Koch's Postulates. H e identified the specific causative agents of anthrax, tuberculosis and cholera . He introduced methods for isolation of bacteria in pure culture.

14. KOCH POSTULATES

15. PAUL EHRLICH (1854-1914) ( FATHER OF CHEMOTHERAPY) His laboratory discovered arsphenamine ( Salvarsan ), the first effective medicinal treatment for syphilis, thereby initiating and also naming the concept of chemotherapy. Ehrlich popularized the concept of a magic bullet. He invented the Staining technique for Gram staining bacteria. The methods he developed for staining tissue made it possible to distinguish between different types of blood cells ,.

16. JOSEPH LISTER (1827-1912) FATHER OF ANTISEPTIC SURGERY He successfully introduced carbolic acid (now known as phenol) to sterilize surgical instruments and to clean wounds. it became the first widely used antiseptic in surgery.

17. ALEXANDER FLEMING (1881-1995) D iscovery of penicillin

18. HOST-MICROBE RELATIONSHIP

19. RELATIONSHIP Microbes are found everywhere. On a daily basis we ingest , inhale, and transport thousands of organisms (i.e ., bacterial, viral, protozoa or parasitic ). Most have no ill effects due to protective mechanisms in our body (i.e., coughing, urinating, sneezing, and defecating). Humans and animals have “friendly” organisms throughout their bodies that survive as normal flora and colonize a host but do not cause disease. However , if these organisms begin to cause any damage to a host by invading tissues and/or producing toxins, they then become pathogens.

20. MICROBES & TYPES Microbes: These are tiny living things that are found all around us and are too small to be seen by the naked eye. They live in water, soil, and in the air. The human body is home to millions of these microbes too, also called microorganisms. It is 2 types according to relationship. Saprophytes : A plant, fungus, or microorganism that lives on dead or decaying organic matter, found in soil and water. Parasites: A n organism that lives on or in an organism of another species, known as the host, from the body of which it obtains nutriment.

21. RELATED TERMS a) COMMENSALS : Living in a relationship in which one organism derives food or other benefits from another organism without hurting or helping it. Example: Staphylococcus epidermidi s on skin, Escherichia coli in gastrointestinal tract. b) PATHOGENS : A bacteria, virus, or other microorganism that can cause disease in a host. c ) Mutualism: In mutualism, both the microorganism and the body work together. An example of this relationship would be cows and the bacteria in their rumen. d) Opportunistic pathogens: Produces disease when host immune system is low. e) Pathogenicity: Ability of microbes to produce disease. f) Virulence: Degree of pathogenicity of microbes.

22. INFECTION & ITS TYPES Infection : The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body. Types are as follow: Primary infection : harmful effect by parasite in the body of host. Reinfection: Subsequent infection by same parasite again. Secondary infection : When the body resistance is lowered by a pre-exiting infectious disease, a new parasite affects. Cross infection : When a patient already from a disease acquires a disease acquire new infection from another from another host. Nosocomial Infection : Cross infection acquired in hospitals in called hospital-acquired or nosocomial infection.

23. Continued.. f) Iatrogenic infection: Iatrogenic infection was defined as an infection after medical or surgical management. g) Sub-clinical infection : Infection which do not show any sign and symptom. Example: Diabetes h) Latent infection : Some parasite remain hidden or latent in host tissue, when host immune system is lowered causes clinical disease.

24. HOW RELATIONSHIP WORKS?

25. NORMAL FLORA Normal flora are the microorganisms that live on another living organism (human or animal) or inanimate object without causing disease. The body contains two types of normal flora: 1) Resident flora (survive for extended periods ) 2) Transient flora (temporary). Normal flora help to provide defenses against invading pathogens: a) By covering adherence sites , b) Producing compounds toxic to other organisms, c) Preventing pathogens from consuming nutrients.

26. Host Defense A microorganism will not be able to invade unless it overcomes an animal’s or individual’s host defenses. Specific host defenses may include: • Skin and mucosal secretions • Non-specific local responses (e.g., pH) • Non-specific inflammatory responses • Specific immune responses (e.g., lymphocytes) The ability for a pathogen to overcome host defenses can be accomplished by two distinct components: a primary pathogen (causes disease in a healthy host) or opportunistic pathogen (causes disease if host is immuno - compromised ).

27. Pathogen Defenses Pathogens contain virulence factors that promote disease formation and provide the opportunity for a microbe to infect and cause disease. The greater the virulence , the more likely disease will occur. Such factors include: • Ability of a pathogen to adhere to a host • Ability of a pathogen to colonize (overcome) a host • Ability of a pathogen to evade host defenses

28. TRANSMISSION OF INFECTION

29. Portal of entry In order to begin infection and eventually cause disease, pathogens must find a transmission route. Transmission of an infectious agent can occur in many ways : T hrough exposed skin (e.g., a cut, abrasion, puncture, or wound) mucous membranes (e.g., gastrointestinal tract, respiratory tract, or urogenital tract )

30. Means of transmission: 1. Blood borne : through sexual transmission, injury or inoculation or blood splashes. 2. Airborne: through inhalation of small particles that remain suspended in the air for long periods of time . 3 . Droplet: also through inhalation. Spread is through close contact with infected persons who may be sneezing, coughing, talking . 4. Contact: through direct or indirect contact. Direct is the transfer of organisms by contact with contaminated hands. Indirect is the transfer or organisms through fomites 5. Common vehicle: through food, water, drugs, blood or other solutions 6. Vector borne : usually through arthropods such as mosquitoes and ticks but cockroaches, ants and flies can also transmit infection.

31. Reservoir Where microorganisms can be found. Within healthcare settings this may include: 1. The environment e.g. dust, bedding, equipment , furniture, sinks or washbowls, bedpans, surfaces) 2. Humans , including patients, staff and visitors, especially from hands.

32. Pathogenesis Pathogenesis can also occur by pathogens invading and breaching the body’s barrier in order to multiply. These organisms have mechanisms that will not allow macrophages (the body’s defense against pathogens) to destroy them. Adherence : Attaching itself to the host’s tissues. This attachment is called adherence and is a necessary step in pathogenicity. Microbes contain ligands, which are projections that attach host receptors or surface proteins.

33. b) Invasion : Microbes begin to invade the host and produce a bacteremia (i.e., presence of bacteria in the bloodstream) or viremia (presence of a virus in the bloodstream ). c) Colonization: Colonization is the multiplication of pathogenic organisms where toxins are produced and the normal flora are overcome. During this stage, pathogens compete with normal flora for space and nutrients. Pathogens usually colonize host tissues that are in contact with the external environment. During colonization, the host begins to show signs of septicemia (i.e., blood infection where bacteria are reproducing).

34. d) Cause Damage: Damage can occur through direct or indirect pathways. Direct methods produce toxins, which are poisonous substances that produce toxemia within a host . Three types of toxins are produced to cause damage: • Exotoxins: Proteins secreted by pathogens that cause damage to the host ( botulinum toxin, tetanus toxin, hemolysin (ruptures red blood cells). • Endotoxins: Toxic substances that are released when a cell is killed ( Lipolysaccharides ). • Exoenzymes : Enzymes that function outside the host cells or tissues. These include coagulase (forms a fibrin clot that “hides” the microbe from phagocytosis), hyaluronidase (breaks connective tissues down), or fibrinase (breaks down blood clots to allow pathogens to continue spreading).

35. Portal of exit These are required for microorganisms to be transmitted from human sources . Portals of exit within healthcare settings include : urinary catheters, wound sites, open skin lesions, skin, and mucous membranes. Semen Urine Stool Sneeze Cough Saliva sputum