Week 5; Day Day 13-15 - Chapter 7: Concepts Of Microbial Disease
Week 5; Day Day 13-15 - Chapter 7: Concepts Of Microbial Disease Biology 233
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This 4 page Class Notes was uploaded by Becca LeBoeuf on Sunday March 6, 2016. The Class Notes belongs to Biology 233 at University of Wisconsin - Oshkosh taught by Teri Shors in Summer 2015. Since its upload, it has received 48 views. For similar materials see Microbiology survey in Biology at University of Wisconsin - Oshkosh.
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Date Created: 03/06/16
Week 5 Day 13: Microbes In The News Use of GMOs to Combat Zika Outbreak: ● No, GMO mosquitoes did not start the Zika virus outbreak! ● British biotech company Oxitec. ● GMO carries a gene that causes mosquitoes to self destruct. ● All GMOs released are sterile males. ● Mate with female mosquitoes carrying Zika virus. ● Females die due to lethal gene from GMO. ● Mosquitoes with lethal gene can be tracked via bioluminescence. Chapter 7 Concepts of Microbial Disease: Biological Associations: ● Symbiosis or “living together,” is an association between two or more species. ○ Mutualism, is a condition in which both species benefit (lichens). ○ Commensalism , one species benefits but the other neither benefits nor is harmed (normal flora). ○ Parasitism, is an association in which the parasite lives at the expense of the other species, the host (all microbial pathogens). ○ Parasites: are the cause of infectious disease. The human normal flora/microbiot is composed mainly of commensal bacteria. LOOK AT FIGURE 07.04. Coccus is a shape!REMEMBER !! Circular shape. Nose: Staphylococcus, Haemophilus. Mouth: Streptococcus, Lactobacillus. Skin: Staphylococcus, Propionibacterium, Acinetobacter, Micrococcus. Stomach: Helicobacter pylori. Small Intestin: Escherichia colLactobacillus (good organism). Large Intestin: Bacteroides, Lactobacillus, Escherichia coli. Urethra: Staphylococcus. The normal flora can be opportunistic pathogens. LOOK AT FIGURE 07.06. Microbes As Agents Of Disease: ● Historically, microbial pathogens have caused infection and untold human suffering. ○ Bubonic plague : a bacterial disease, killed millions in the fourteenth century. ○ Smallpox: virus was a scourge for centuries, until eradicated in 1980. ○ Late 1800s: ■ Louis Pasteur proved that microbes were responsible for fowl cholera and anthrax in sheep. ■ Robert Koch established that tuberculosis was caused by a bacterium, later name Mycobacterium tuberculosis. Koch’s Postulates: 1. Association: the causative agent must be present in every case of a specific disease. 2. Isolatio: the causative agent must be isolated in every case of the disease and grown in pure culture. 3. Causation: the causative agent in the pure culture must cause the disease when inoculated into a healthy and susceptible laboratory animal. 4. Reisolation: the causative agent must be reisolated from the laboratory animals and be identical to the original causative agent. Pathogenicity And Virulence: ● Infective Dose (I: minimal number of microbes necessary for infection. ○ More virulent organisms have smaller IDs than less virulent organisms. ■ Vibrio cholerae (causes cholera) ID = one million. ■ Mycobacterium tuberculosis (causes TB) ID = 10. ● Pathogenicity: is the ability to cause disease. ● Virulence: is a measure of pathogenicity, it encompasses two types of virulence factor: ○ Defensive strategie that allow microbes to escape destruction by the host immune system (adhesins, capsules, antigenic variation, etc). ○ Offensive strategi that result in damage to the host (exoenzymes, exotoxins, endotoxins, etc). ● Endotoxins: produces shocklike symptoms, chills, fever, weakness. ● Capsules: interfere with uptake of bacteria (phagocytosis). ○ Removal of the capsule from encapsulated bacteria makes them more susceptible to phagocytosis. ● Defensive Strategies Continued elicobacter pyl the bacterium that causes peptic ulcers, secretes the enzyme urease, which enables it to survive in the highly acidic environment of the stomach. LOOK AT FIGURE 07.12. ● Offensive Strategies: Toxins. ○ Endotoxinis part of the LPS in the outer membrnramnegativecells; it causes shock, chills, fever, weakness, small blood clots, and possibly death. ○ Exotoxins are proteins synthesized by the microbe and secreted into the host’s tissues. ■ Cytotoxins kill or damage cells. ■ Neurotoxins block nerve impulse transmission. ■ Enterotoxins, affect cells lining gastrointestinal tract. ○ Taxoid, detoxified toxin, retains its antigenicity. Stages Of Microbial Disease: ● Incubation: period between initial infection and appearance of symptoms, considerable variation among diseases. ● Prodromal : period in which early symptoms appear; usually short and not always well characterized. ● Illness: period during which the disease is most acute and is accompanied by characteristic symptoms. ● Decline: period during which the symptoms gradually subside. ● Convalescence : period during which symptoms disappear and recovery ensues. Opportunistic Pathogens : an infection caused by bacterial, viral, fungal or protozoan pathogens that take advantage of a host with a weakened immune system or an altered microbiota (such as a disrupted gut flora). Many of these pathogens do not cause disease in a healthy host that has a normal immune system. Toxins: an antigenic poison or venom of plant or animal origin, especially one produced by or derived from microorganisms and causing disease when present at low concentration in the body. Pathogenesis : the manner of development of a disease. Virulence: the degree of pathogenicity within a group or species of parasites as indicated by case fatality races and/or the ability of the organism to invade the tissues of the host. The pathogenicity of an organism its ability to cause disease is determined by its virulence factors. Microbes In The News CDC Investigating WI Outbreak: ● 44 bloodstream infections. ● Majority over age 65. ● Immune compromised. ● Elizabethkingia anophelis. ● First 6 cases: December 29Jan 4th. ● Contracted through healthcare setting. ● Cases occurred between November 1, 2015 and March 2, 2016. ● Residents of Columbia Dane, Dodge, Fond Du Lac, Jefferson, Milwaukee, Ozaukee, Racine, Sauk, Washington, and Waukesha counties. Elizabethkingia meningoseptica: ● Gram negative rod, aerobic. ● Cluster of cases in West London teaching Hospital, England, 2014. ● Ventilator patients. ● Contaminated water. ● Hand sanitizer: ○ 20042011 recalls of sanitizer. ● 18 people dead, dozens sick. Meningococcal meningitis: ● Can be life threatening. ● Caused by Neisseria meningitidis (Gdiplococci). ● Signs And Symptoms: ○ Stiff, arched neck. ○ Pounding headache. ○ Diagnosis: gram stain of cerebrospinal fluid via spinal tap (look for gram negative diplococci bacteria also has a capsule). ○ Rash (bright red patches, progresses to blueblack spots). ○ If left untreated, 50% mortality rate. ● Problems During The Disease And Treatment: ○ Patients are given a large dose of antibiotic, usually penicillin. ○ Penicillin flowing through the bloodstream rapidly kills the bacteria. ○ As the bacteria are killed, they release even more toxin. ○ It takes up to two days for the poison to be cleared from the body and the siege to end. ○ Dangerous clots form, blocking blood vessels = tissues start to die. ● The Meningitis Belt In Africa: ○ The MenAfriVac vaccine will be rolled out to 12.5 million people in Burkina Faso, 4 million people in Mali and 4 million people in Niger.
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