MICROB 3200 1nd EditionExam # 1 Study Guide Lectures: 1 - 3Lecture 1 (August 26th)7:46 AMI. What is microbiology?a. "The study of micro organisms (including bacteria, viruses, fungi, & parasites) which are of medical importance"b. Bacteria is highly adaptive.I. Why important?a. Morbidity & Mortality i. 2nd leading cause of death worldwide (~23%)a. Healthcare Associated Infections (HAIs) i. Rapidly increasing cause of death in healthcare settingi. Approximately 30% of hospital patients are on antibiotics at any one timea. Antibiotic resistancei. They've evolved mechanisms to resist antibiotics, making this more of a problemi. Diseases we've controlled may get to a point where we can'tI. What information is important for you?a. Clinical setting:i. Information that you can use to diagnose and manage a patient with infectious diseasea. Research setting:i. Information that you can use to develop new therapies against infectious diseaseI. THINK LIKE A PHYSICIAN AND ASK 7 BASIC QUESTIONSa. WHO is at risk?a. WHAT tests should be performed?a. WHERE is the organism prevalent (body site and geographic area)b. WHEN is the isolation of the organism important?a. WHY is this organism able to cause disease?a. WHICH species are medically important?a. HOW is the disease managed and prevented? Many pathogens aren't trying to cause disease. A lot of issues are actually caused by our immune system trying to control it. MICROBIAL PATHOGENESIS I I. SYMBIOTIC RELATIONSHIPS BETWEEN MICROBES AND THEIR HOSTSa. We host ~100 million microorganismsb. Mutualismi. Both species benefit from the associationi. EX: Escherichia coli in human intestinal tracta. Commensalismi. One species benefits without harming the otherii. EX: Staphylococcus epidermidis on human skina. Parasitismi. One species derives benefit while damaging its hosti. EX: Mycobacterium tuberculosis → human specific pathogenI. Normal Microbiotaa. Body is colonized by numerous mutualistic and commensal symbiontsa. Microbes that colonize the body's surfaces without normally causing disease constitute the body's normal microbiota (flora, older term)i. Many organisms are beneficial → intestinal E. coli strains produce Vitamin Ka. Resident microbiotai. Remain a part of the normal microbiota throughout our livesi. Many of these organisms protect us against infection & pathogensa. Transient microbiotai. Remain in the body for only a few hours, days, or weeksI. Pathogenicitya. Pathogenicity: the ability of a organism to cause disease within a hosti. Pathogenicity is the product of an organism’s VIRULENCE FACTORSa. Virulence: the relative ability of an organism to cause disease within the same hosti. The virulence of strains within a species can varyi. Quantitative measure: Median infectious dose (ID50)I. MEDIAN INFECTIOUS DOSE (ID50)a. Median infectious dose (ID50)i. the number of microorganisms required to cause an infection in half the members of a tested population a. High virulence  few microorganisms sufficient to initiate disease (\ low ID50 ≡ highly contagious organism)I. Low/ moderate virulence  many microorganisms required to initiate disease (\ high ID50 ≡ moderately contagious organism)a. Summary:  Number of organisms   likelihood of diseaseI. INFECTIOUS DOSE OF VARIOUS FOODBORNE BACTERIAL PATHOGENSa. Escherichia coli : very large (106 - 108 of organisms)a. V. cholerae : quite large ( 104 - 105 of organisms)a. Campylobacter jejuni : low (500 organisms)a. Shigella : very low (~10 organisms) i. i.e. Shigella is highly virulent with a Low ID50I. Opportunistic Pathogensa. A usually harmless microbe that becomes pathogenic under favorable conditions; Often a member of the normal microbial florab. Conditions that provide opportunities for pathogensi. Immune suppression 1. various causesi. Changes in relative abundance of normal microbiota 1. antibiotic treatmentsi. Introduction of normal microbiota into unusual site in the body1. medical devicesa. Pseudomonas aeruginosai. Pseudomonas aeruginosa is a prototypic example of an opportunistic pathogen of humansi. While healthy individuals are rarely infected with P.a., those with compromised immune systems (diabetics, cancer patients, burn victims) are highly susceptiblei. Diabetic Ulcer1. Tissue infected with P.a.1. Due to poor circulation/ intrinsic antibiotic resistance of P.a., prognosis is poora. Summaryi. Low probability of causing disease in normal healthy hostI. Increased probability of causing disease in immunocompromised hosti. Responsible for high morbidity and mortality in the developed worldI. Primary Pathogensa. Obligate pathogens: Organisms which must cause disease to both SURVIVE and be TRANSMITTEDi. Often host restricted, e.g. human specific pathogen Neisseria gonorrhoeaea. Strict pathogens: Organisms which typically cause disease in one or more hosts. Can survive in the environment, e.g. Bacillus anthracis b. “Accidental pathogens”: Commensal organisms which occasionally cause disease  negative effect on both the host and the pathogen, e.g. Neisseria meningitidisa. Summaryi. High potential for causing diseasei. Can be prevented by immunizationi. Responsible for significant morbidity and mortality in the developing worldLecture 2 (August 28)Thick cell wall causes cells to retain dye (gram-positive) Cell Wall Structure Prokaryotic Cell Wall-Provides structure and shape and protects cell from osmotic forces-Assists some cells in attaching to other cells or in eluding antimicrobial drugs-Absent in animal cells-Target of important antibiotics-Use what inhibits animals to make cell wall on bacteria to prevent them from having cell wall Bacterial Cell Wall-Most have peptidoglycan (Sugar & peptide)-Polysaccharide polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)oAutomating polymer, nag nam nag nam nag nam-Not found in Mycoplasma speciesoThey don't have a cell wall-Only bacteria known not to-Two basic types: Gram+ and Gram---Not talking about teichoic acids-Endotoxin-toxic component within cell wall--Due to thin extra layer (peptidoglycan), it has to get molecules through the inner membrane-Gram-negatives are more complicated---Like a deck of cards-It's as though the first card was stapled to the second, second to third, yeah yeah yeah-Each chain is bolted to the next Cross-link gives rigidityAntiphagocytic-give bacteria protection from being eaten by WBCMitogenic-allows cells to dividePyrogenic-deals