Microbiology PDF

**Microbiology** The study of organisms too small to be seen without magnification Originated with invention of the microscope **Microorganisms** include: Bacteria, Viruses, Fungi, Protozoa, Helminths (worms), Algae, Prions **Branches of Study Within Microbiology:** Immunology Public health micr...

**Microbiology** The study of organisms too small to be seen without magnification Originated with invention of the microscope **Microorganisms** include: Bacteria, Viruses, Fungi, Protozoa, Helminths (worms), Algae, Prions **Branches of Study Within Microbiology:** Immunology Public health microbiology and epidemiology Food, dairy and aquatic microbiology Biotechnology Genetic engineering and recombinant DNA technology Manipulating genes **Microbes are Involved in**: Nutrient production and energy flow Decomposition Biotechnology production of foods, drugs and vaccines Genetic engineering Bioremediation Infectious disease **Classification of Microorganisms ( Protists)** **I- Cellular:** 1- Prokaryotes \*No nucleus or primitive nucleus (pro= before or early; karyon= nucleus) \*e.g. Archaea, bacteria, & blue-green algae 2- Eukaryotes \*Mature nucleus \*e.g. Algae ( other than blue-green), fungi & protozoans **II- Non-Cellular:** \*e.g. Viruses, viroids, prions **Taxonomy:** The formal system of organizing, classifying, and naming living organisms **\*Bacteria:** prokaryotic, unicellular organisms **\*Archaea:** prokaryotic, unicellular organisms that live in highly salty or extreme temp. environment **\*Algae:** eukaryotic organisms, performing photosynthesis **\*Fungi:** eukaryotic, unicellular or multicellular organisms **\*Protozoa:** eukaryotic, unicellular or multicellular organisms **\*Viruses:** noncellular, seen only by electron microscopy, consist of NA surrounded by a protein coat **\*Viroids:** noncellular, plant pathogens RNA, cannot produce proteins nor have a protein coat **\*Virusoids:** noncellular, mostly plant pathogens RNA, but one agent infects humans (HDV) **\*Prions:** noncellular, normal animal proteins that become infectious (lack NA so, they are not viruses) **Bacterial Life Cycle** All bacteria live in Vegetative Form: metabolically active, growing, multiplying phase that can cause infection. In unfavorable environmental conditions, some vegetative cells can form spores (endospores) by a process termed (sporulation). Spore Form: inert, resting, non growing, non multiplying, highly resistant form that can live for years. When environmental conditions improve, spore form changes into vegetative form (germination) **Cytoplasmic Organelles** **1-Mitochondria:** \*Long,fluid-filled sacs \*Contain ATP {power site} **2-Ribosomes:** \*Small granules of RNA \*some are free in cytoplasm, others attached to endoplasmic reticulum {ER} \*For protein synthesis **3-Endoplasmic Reticulum:** a- Smooth: functions in lipid synthesis b- Rough: functions in protein synthesis {for transport} **4-Golgi Apparatus:** \*Flat sacs, connected to the ER \*Packaging & shipping center **5-Lysosomes:** \*Sacs containing digestive enzymes that break down particles e.g. bacteria **6-Centrioles:** two rods at right angle to each other, function in cell division **7-Cilia:** short, many, hair like processes that create a wave like motion to move substances across cell surface {e.g. in respiratory tract} **8- Flagella:** \*long, few \*move the cell itself **9- Chloroplasts:**\*in algae & plant cell: \*convert sun energy into chemical energy (photosynthesis) **Defense Mechanism Against Infection** 1- Nonspecific mechanisms act against all harmful agents, so provide nonspecific resistance 2- Specific mechanisms act against certain agents, so provide specific resistance {immunity} Lack of resistance is called susceptibility Virulence is the degree of pathogenicity or disease provoking power of a specific microbe **Nonspecific Defense Mechanisms** 1- Intact skin and mucous membranes 2- Fluids like tears, saliva and urine flush pathogens out of the body 3- Complements: group of proteins normally found in plasma in an inactive form, upon contact with foreign bodies, each protein activates the next in an orderly manner, so that all complements become active and induce: \*phagocytosis \*inflammation 4- Interferons: chemical substances produced by infected cells and protect uninfected cells against viral infection 5- Phagocytosis: Two types of phagocytes: a- Neutrophils: small granular leukocytes b- Monocytes {macrophages}: large agranular leukocytes (macrophages in between liver cells are called Kupffer cells) 6- Inflammation {nonspecific defense mechanism in response to tissue damage} - Signs: redness, hotness, swelling, pain and may be loss of function Inflammation may be: A- Localized:\*contained in a specific area B- Systemic {generalized}:\*widespread \*characterized by 3 additional features: 1- Leukocytosis: due to stimulation of bone marrow to produce more WBCs 2- Fever: due to production of pyrogens that affect the hypothalamus to increase body temperature 3- Hypotension: due to generalized vasodilation & increased capillary permeability **Specific Defense Mechanisms {Immunity}** **A- Cell-mediated Immunity:** Produced by T- cells- mainly against viruses and fungi Some types of activated T-cells: - Killer T-cells (destroy the antigen) - Memory T-cells: remember the antigen so that the second encounter produces a faster and more intense response than the first one **B-Antibody-mediated Immunity {humoral}:** Produced by B-cells- mainly against bacteria Two types of activated B-cells: - Plasma cells: produce antibodies - Memory B-cells: recognize the same antigen on second encounter to produce "the secondary response" **Normal Flora (Microbiota) \*Resident flora:** normal flora throughout the life of a person e.g. S. epidermidis & E. Coli **\*Transient flora:** remain for a few hours, days, or months before they vanish e.g. Bacillus Laterosporus ( sometimes lives in intestine to limit growth of Candida) Normal flora are usually protective so, they do not cause diseases in their normal habitat in a healthy person When balance is interrupted, normal flora can become opportunistic pathogens **Modes of Transmission** **Contact Transmission** 1- Direct Physical Contact: between hosts without an intermediate object Person-to-person by touching, kissing, sexual intercourse Examples: Respiratory tract infections, staphylococcal infections, measles, scarlet fever, sexually transmitted diseases 2- Indirect Contact: pathogen is transmitted by a fomite (nonliving object) e.g., tissues, handkerchiefs, towels, bedding, toys, clothes, diapers, eating utensils, drinking cups, medical equipment and devices **Droplet Transmission**: \*Infectious agents are transmitted via respiratory droplets \*Organisms travel less than a meter **Airborne Transmission:** \*Organisms travel more than 1 meter **Water-borne & Food-borne Transmission**: Through untreated or poorly treated sewage & undercooked foods, or food prepared under unsanitary conditions \--Gastrointestinal diseases---giardiasis, amebic dysentery, cholera, shigellosis and Hepatitis A & E **Bodily Fluid Transmission:** Blood, urine, saliva, and other bodily fluids **Vector Transmission:** Animals, especially arthropods 1- Biological Vectors: Biting insects, including mosquitoes, ticks, lice, fleas, blood-sucking flies 2- Mechanical Vectors: Passively carry agents to a new host by their feet or other bodily parts **Applied Microbiology** Food production: yogurt, bread Alcoholic beverages: wine, beer Treatment of water supplies Pharmaceutical agents: penicillin Agriculture: fertilizers Bioremediation: petroleum Forensics: medicine, criminal justice, bioterrorism Energy: ethanol, methane