MCB 100 1st Edition Lecture 31Outline of Last Lecture I. Mycoplasma II. Listeria III. Lactobacillus IV. StreptococcusV. Pneumonia VI. Bacterial meningitis Outline of Current Lecture I. EnterococcusII. Lactococcus lactisIII. StaphylococcusIV. High G + C gram-positive bacteria (actinobacteria)V. Propionibacteria Current LectureI. Enterococcus a. Entero = intestines b. Relatively safe to work withc. Gram positive cocci that come in pairs or short chains, catalase negative, lactic acid fermentation, difficult to distinguish from streptococcusd. Natural habitat is in the large intestinee. More tolerant to salt and bile salts than streptococcusf. Genomic DNA sequence analysis indicated a separate genus would be appropriateg. Enterococcus faecalis and enterococcus faecium are the most common examplesh. May cause opportunistic urinary tract infections, bacteremia, endocarditis and meningitis if they get out of the intestinesi. VRE = vancomycin resistant enterococcus II. Lactococcus lactis a. Used to be called a streptococcus because it’s a gram positive coccus that comes in chains and doesn’t make catalase (an enzyme that breaks down hydrogen peroxide). It is used to make cheese. b. Its' metabolism is homolactic acid fermentationIII. Staphylococcus (firmicutes)a. Clusters, aerobic (catalase positive- able to break down H2O2) b. Staphylococcus epidermidisThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Considered normal flora of skinii. Contributes to body odoriii. Can be an opportunistic pathogenb. Staphylococcus aureus i. Common- but not considered "normal flora", about 85% of people have it in nostrils ii. Spread person to person by respiratory droplets (direct) and by fomites (indirect)iii. There are many strains iv. Many possible virulence factors (coagulase, hemolysin, toxins)v. Some strains are beta-hemolytic vi. Yellow- orange pigmented colonies (aureum = gold) vii. Frequently involved in skin and burn infections, impetego, acneviii. Excretes several cytolytic or membrane damaging toxins ix. Staphylococcal food poisoning caused by a heat stable enterotoxinx. Toxic shock syndromexi. Staphylococcal scalded skin syndrome (mostly seen in babies)1. A rare exfoliative disease which occurs mainly in children2. Caused by strains that make exfoliative toxins3. Treatment: penicillin or vancomycin if the staph. Strain is resistant to b-lactam drugs4. Healing generally occurs within a feel weeks ii. Coagulase- enzyme that causes fibrin to clot, this seems to protect the bacterium from phagocytesiii. Hyaluronidase helps the infection to spread by breaking down hyalyronic acid which helps hold cells and tissues together like glue II. High G + C gram-positive bacteria (actinobacteria)a. Corynebacteriumi. Non-spore forming rods, arranged in V-shaped palisades ii. Ex. C. diphtheria1. infects throat, excretes a toxin that enters host cells and inactivates 80S ribosomes, diphtheria is characterized by a gray curtain-like sheet of deadtissue hanging down in the throat 2. Caused by Corynebacterium diphtheria 3. Non-spore forming4. Gram positive5. Rod-shaped bacteria6. Snapping cell division produces palisades7. Infection tends to be limited to the pharynx8. Toxin is an A-B type toxin that can enter human cells and inactivate 80S ribosomes9. Immunization uses toxoid- DTaP10. Treatment should include both antitoxin and antibiotic to prevent disease and to help stop transmission of infection- typically penicillin or erythromycin is used for treatment 11. Can be spread by microdroplets and fomites 12. Infection has a 3-5 day incubation period 13. Exotoxin gene is located on a lysogenic phage 14. Toxin can cause tissue damage leading to an accumulation of debris (pseudomembrane)15. Toxin can become systemic and may cause heart and kidney failure in 7-10 days 16. Immunization to toxin doesn't prevent organism from colonizing throat but microorganism itself is harmless; toxin is the problem II. Propionibacteria a. Propionibacterium acnesi. small, gram-positive, rod-shaped, non-spore forming, anaerobic, diphtheroids ii. Commonly found growing on sebum within the sebaceous glands of the skin; excessive oil formation increases bacterial growth causing localized inflammationb. Propionibacterium freudenreichiii. Makes propionic acid and carbon dioxide as fermentative waste productsii. Used to make swiss cheeseiii. Propionic acid adds the slightly rancid bouquet of swiss cheese while the CO2 gas forms bubbles in the curds that makes the
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