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Microbiology – Chapter 13

Microbiology – Chapter 13. Pathology: Science of study of disease Etiology: Cause of disease; often microbial Flu – etiological agent, Influenza virus Tb – M. tuberculosis Pathogenesis: development of disease in the host - Norwalk virus; Fecal – oral, diarrhea

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Microbiology – Chapter 13

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  1. Microbiology – Chapter 13 Pathology: Science of study of disease Etiology: Cause of disease; often microbial Flu – etiological agent, Influenza virus Tb – M. tuberculosis Pathogenesis: development of disease in the host - Norwalk virus; Fecal – oral, diarrhea Disease: altered state of health, host body is changed, upset of homeostasis

  2. Microbiology – Chapter 13 Epidemiology: Science of the study of how diseases are acquired and spread in a population Outside assignment 3: Note that the last question has been changed to focus on MDR bacterial infections. Be sure to get a copy of the last page from instructor ** You may have to do some research ato answer all of the questions. Use other Micro. Books or other research tools. ***

  3. Microbiology – Chapter 13 Relationship between organisms: Normal flora: normal inhabitants of the host ex. S.epidermidis on skin, E.coli in intestine Commensalism – One organism benefits; the other unaffected; can be opportunistic infector Mutualism: both benefit; E. coli makes us Vit. K; We provide nice environment and food

  4. Microbiology – Chapter 13 Parasitism: One benefits at the other’s expense; tapeworm or leach Virulence: potency; how quickly they infect, spread, cause tissue damage or disease symptoms Influenza A H5N1, very virulent form of flu, or encapsulated pneumococci Virulence factors: factors that cause disease or aid in spread of disease quickly in host or to other hosts (more later)

  5. Microbiology – Chapter 13 Pathogen: actual agent of disease, MRSA – S. aureus BACTERIAL, VIRAL, FUNGAL, HELMINTH Carrier: Infected healthy individual, no symptoms (asymptomatic), or very mild form of disease, yet they both can spread disease to others – many bacterial and viral pathogens Classic case was typhoid Mary (look it up)

  6. Microbiology – Chapter 13 Reservoir: Where pathogen is maintained , can be in an organism (animal), in the environment (stagnant water - Legionella), or even in soil (Clostridia) Vector: Agent that spreads pathogens from host to host 1. Arthropod: flea; mosquito, tick 2. Inanimate: things, toys, dirty hands, needles, (sometimes called “fomites”)

  7. Microbiology – Chapter 13 Nosocomial infections: hospital acquired infections – see table in text and know it Next slide****** MRSA both HA and CA Pseudomonas - respiratory impaired, burn patients E. coli and Proteus – UTI; long term catheter patients

  8. Fig. 13.13

  9. Review Koch’s postulates

  10. Microbiology – Chapter 13 Nine routes of infection **** Know this; be able to list and give an example of each**** 1. Respiratory droplets: cough sneeze, air born droplets Flu, colds, Strep throat even Staph infections of wounds

  11. Fig. 13.12

  12. Microbiology – Chapter 13 2. Fomites Inanimate objects that spread disease agents Shared drinking cups, baby toys in a nursery, contaminated sharps ** add pictures**

  13. Microbiology – Chapter 13 3. Direct body contact- Oh what fun!! Person to person: STD, Impetigo

  14. Microbiology – Chapter 13 4. Fecal – Oral Feces contamination of food water, even dirty hands (hands are a vector, or even a house fly or roach) Enteric diarrheal disease;Helminth Protozoans: Giardia, Balntidium

  15. Microbiology – Chapter 13 5. Arthropod Vectors Flies, fleas, mosquito, tick

  16. Fig. 13.11

  17. Microbiology – Chapter 13 6. Airborne Particles suspended in air (dry; dust), travel long distances; tb, anthrax spores (potential for WMD), Respiratory fungal infections (Histoplasma)

  18. Microbiology – Chapter 13 7. Parenteral Direct transmission via blood: universal precautions HIV, HVB, HVC

  19. Microbiology – Chapter 13 8. Deep Wound trauma Gas gangrene and tetanus, even wound botulism Beaman’s world infant tetanus

  20. Microbiology – Chapter 13 9. Horizontal: Mother to infant Prenatal: across the placenta; HIV Perinatal: at birth, STD like gonorrhea and syphilis, even Chlamydia blindness

  21. Microbiology – Chapter 13 • 9. Horizontal: Mother to infant • Perinatal: at birth, STD like gonorrhea and syphilis, even Chlamydia blindness

  22. Microbiology – Chapter 13 Virulence factors Virulence factors – factors that aid or enhances the microbes ability to invade and spread within the host (know for test) Ex. List the categories of “virulence” factors in microbes; explain each category, and give an example of a disease causing agent for each category. Adherence: In order for a microbe to cause disease it first must adhere to a host surface. Some microbes produce materials or structures that allow them to adhere (stick) to membranes or surfaces, and thus escape defenses Pili (fimbriae) – Neisseria gonorrhea, if a strain has no pili it is not pathogenic. The chemicals that allow such attachment are called “adhesins” – They are often glycoproteins or protein that bind to receptors on host cell surfaces. Glycocalyx – The capsule again is a tightly bound polyscaccharide material on the outside of certain bacterial cells (part of a bacterial envelope). Streptococcus pneumoniae is good example. Virulent strains are encapsulated; non-virulent strains are not. Recall the classic “Griffith experiment” from chapter 9? Transformation? Spikes – Viral envelopes of some viruses, Influenza a, H5N1

  23. Fig. 13.4

  24. Microbiology – Chapter 13 Other adhesions N. menigitidis (bacterial meningitis agent) produces protein a, a surface adhesion on the pili Mycoplasma pneumonia (atypical bacterial pneumonia) has a surface adhesion that binds to receptor on mucus membrane lining of the respiratory tract

  25. Virulence Factors Other Adhesions SEM of Pseudomonas, Gram (-)

  26. Microbiology – Chapter 13 Toxins – Poisonous microbial bypoducts that are produced by the microbe and diffuse into tissues causing damage/ enhance invasion/ avoid defenses Exotoxins – excreted outside of cell, both Gram+ and Gram – bacteria produce some of these highly destructive proteins. Staphylococcus aureus - Staph exotoxin that causes FBI Another causes “SSSS” Staph Scalded Skin Syndrome (exfoliate) C. botulinum – most powerful neurotoxin, - a taste can kill you Streptococcus pyogenes - has several tissue destroying toxins; Necrotoxin of flesh eating Strep would be a good example. Endotoxin – Released by many Gram (-) bacteria when cells lyse, Examples: Lipid A, lps in many pathogenic enteric bacteria like Shigella, can cause high fevers and even shock.

  27. Endotoxin - Lipid A – raises fever, and shock in Gram (-) pathogens

  28. Endotoxin - Lipid A – raises fever, and shock in Gram (-) pathogens

  29. Fig. 13.6

  30. Microbiology – Chapter 13 Enzymes that help invasion Collagenase – breaks down collagen, the protein holding cells together, thus allows spreading. Clostridia that invade tissue can produce these proteases to digest connective tissue elements (C. perfringens) Hyaluronidase – breaks down hyaluronic acid, the polysachharide that may hold some cells together, S. pyogenes produces such an enzyme Causes necrosis and blackening of tissue (inches of progression in hours) Coagulase – Affects the fibrin in blood causing it to clot, Staph aureus produces one and maybe prevents phagocytosis. Hemolysin – This exotoxin is an enzyme and lyses RBC. S. pyogenes Alpha and Beta Hemolysis of the Strep.

  31. Virulence Factors • Enzymes: Collagenase, Hyaluronidase

  32. Virulence Factors • Enzymes: Hemolysin – lyse RBC

  33. Microbiology – Chapter 13 Evading defenses – Once in tissue some organisms can “evade” the natural defense of a host. Capsule – Phagocytes can’t engulf the pathogen – S. pneumoniae Surface proteins – Proteins prevent phagocytosis (leukostatin, leukocydins of Staph and Strep) Survive inside phagocyte – Get a free ride and spread (Tubercle bacillus, Listeria bacillus, and others) Evade immune response - Genetic variability occurs and the result is that antibodies lose effectiveness quickly – genetic shift/drift of the antigenic nature of the Influenza A virus, (FDA today is meeting to SWAG for next years vaccine)

  34. Virulence Factors • Evade defenses: Capsule – resisting phagocytosis, Strep.

  35. Virulence Factors • Adherence: Glycocalyx (capsule)

  36. Virulence Factors • Surface proteins : Leukocydin, S. aureus • (MRSA) – Attacks WBC’S

  37. M. tuberculosis inside lung macrophage

  38. Virulence Factors • Survive inside phagocyte, tubercle bacillus

  39. Evading immune response • Influenza

  40. Virulence Factors • Evade immune response : Influenza A • H5N1 – “Bird Flu”

  41. Microbiology – Chapter 13 Iron binding – Iron is tightly bound in our bodies and microbes need it to grow, Those organisms that can acquire it have and advantage and can spread faster; more virulent – Cholera is an example, HIB (H. influenza B)

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