Chapter 21

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Chapter 21

  1. 1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint® Lecture Slide Presentation prepared by Christine L. Case M I C R O B I O L O G Y a n i n t r o d u c t i o n ninth edition TORTORA  FUNKE  CASE Part A21 Microbial Diseases of the Skin and Eyes
  2. 2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skin  Perspiration salt inhibits  Lysozyme hydrolyzes peptidoglycan.  Sebum fatty acids inhibit  Kerotin waterproofing protein  Defensins are antimicrobial peptides (also found in GI membranes). Figure 21.1
  3. 3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mucous Membranes  Line body cavities.  The epithelial cells are attached to an extracellular matrix.  Cells secrete mucus, acidic nature  Some cells have cilia.
  4. 4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Normal Microbiota of the Skin  salt-tolerant & resistant to drying  Hand washing can reduce numbers, some remain in follicles and reestablish populations  Malssezia furfur (yeast) capable of growing on oily skin, dandruff Figure 14.1a
  5. 5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbial Diseases of the Skin  Vesicles- small fluid filled  Bullae- larger  Macules- flattened lesions  Papules- raised lesions  Pustules- raised lesions containing pus
  6. 6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Microbial Diseases of the Skin Figure 21.2
  7. 7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bacterial Diseases of Skin  Two genera, Staphylococcus and Streptococcus are frequent causes of skin-related diseases  This bacteria comes into contact with skin often  Both produce invasive enzymes and damaging toxins that contribute to the disease process
  8. 8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Staphylococcal Skin Infections  S. aureus  Most pathogenic of staphylococci  Gram-positive cocci and coagulase-positive (clots protect microbes from phagocytosis)  Toxins= enterotoxins affecting GI tract  Hospital environment problem b/c carried in by patients, staff, visitors infecting surgical wounds  . Nasal passage favorable environment or via hair follicle
  9. 9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Staphylococcal Skin Infections  S. epidermidis  Gram-positive cocci and coagulase-negative  90% of normal biota, pathogenic on broken skin: catheter in veins  On the surface of the catheter the bacteria are surrounded by slime layer (biofilm) that protects them from drying out
  10. 10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Staphylococcal Biofilms Figure 21.3 Slime producing bacteria, covers the surface
  11. 11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Staphylococcal Skin Infections  Folliculitis: Infections of the hair follicles.  Sty: Folliculitis of an eyelash.  Furuncle: Abscess; pus surrounded by inflamed tissue.  Carbuncle: Inflammation of tissue under the skin: deep, & firm, extensive damage, generalized illness & fever
  12. 12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Staphylococcal Skin Infections  Impetigo of the newborn  Carry the risk of toxins in the blood= toxemia  Scalded skin syndrome- under age 2, serious  Toxic shock syndrome- once associated with tampons, now surgery packing Figure 21.4
  13. 13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Streptococcal Skin Infections  S. pyogenes- cause a wide range of diseases beyond this chapter  Secrete toxins  Hemolysins-lyse RBC  Streptokinases-blood clot dissolving enzyme  Hyaluronaidase-CT dissolving enzyme  Deoxyribonucleases- DNA degrade enzyme  Streptolysins- lyse RBC, toxic to neutrophils Figure 21.5
  14. 14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Streptococcal Skin Infections  Erysipelas  Infects dermal layer  Could enter the  Bloodstream-sepsis  Impetigo  spread by touch Figures 21.6, 21.7
  15. 15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Invasive Group A Streptococcal Infections  Flesh eating bacteria  Destroy tissue as fast as surgeon can remove it.  40% mortality  Cellulitis-solid tissue  Myositis-muscle  Necrotizing fasciitis- muscle covering Figure 21.8
  16. 16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Infections by Pseudomonads  P. aeruginosa  Capable of living on traces of organic matter (soap films, cap liner adhesives)  Pyocyanin produces a blue-green pus  P. dermatitis- 2weeks duration, pools & hot tubs  Otitis externa-swimmer’s ear  Post-burn infections of 2nd & 3rd degree, may produce blue/green pus (pigment pyocyanin)
  17. 17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acne  Most common skin disease, Classified by lesion in 3 categories  1. Comedonal acne occurs when sebum channels are blocked with shed cells. Whiteheads- comedos, blackheads due to lipid (sebum) oxidation  2. Inflammatory acne- sebum being metabolized by bacteria attracts WBC which secrete enzymes damaging hair follicle creating pustules & papules  Treat to reduce sebum production
  18. 18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acne  Nodular cystic acne (progressive inflammatory acne) has nodules or cysts- inflamed lesions filled with pus deep within the skin, scarring
  19. 19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viral diseases of the Skin  Many, although system in nature and transmitted by respiratory or other routes, are most apparent by their effects on the skin.
  20. 20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Warts  Benign skin growths, transmitted by contact  After infection, incubation of several weeks  Papillomaviruses- 50 types  Removal by cryotherapy, electrodesiccation  Imiquimod (stimulates interferon production)  Laser as last resort b/c the production of aerosols
  21. 21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Poxviruses  Smallpox (variola)  15th century France where syphilis introduced as “the great pox” (la grosse verole)  Transmitted via respiratory & moves into blood stream to the skin  1st disease of immunity & eradicated  Vaccination in US ended in 1970 Figure 21.9
  22. 22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Poxviruses  Monkeypox  Appeared among zoo monkeys, occasional human outbreaks  Transmitted by respiratory  Prevention by smallpox vaccination
  23. 23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Herpesviruses  Varicella-zoster virus  (human herpes virus 3) Chickenpox pus-filled vesicles  Transmitted by the respiratory route  Causes pus-filled vesicles  Virus may remain latent in dorsal root ganglia (near spine) Figure 21.10a
  24. 24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Shingles (Latin-cingulum= girdle or belt)  Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin,  Typically distributed along waist  Vaccine 1995 Figure 21.10b
  25. 25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Herpes Simplex 1  Human herpes virus HHV1  Tranmitted by oral or respiratory  Cold sores or fever blisters (vesicles on lips)  Herpes gladiatorum, skin contact among wrestlers (vesicles on skin)  Herpes whitlow, contact among nurses, physicians, dentists (vesicles on fingers)  HHV-1 can remain latent in trigeminal nerve ganglia.
  26. 26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Herpes Simplex 2  Transmitted by sexual contact  HHV-2 can remain latent in sacral nerve ganglia.  Very rare: HHV 1 or 2 can spread to brain  Herpes encephalitis (HHV-2 has up to a 70% fatality rate)
  27. 27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Measles (Rubeola)  Measles virus  Extremely contagious  Transmitted by respiratory  Macular rash and Koplik's spots (tiny red patches with white specks in mouth)  Vaccine MMR, given at 12 mo  Encephalitis in 1 in 1,000 cases. Figure 21.14
  28. 28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Rubella (German Measles)  Rubella virus  Transmitted respiratory  Macular rash and fever  Congenital rubella syndrome causes severe fetal damage, infection during 1st trimester  Vaccine 1969 Figure 21.15
  29. 29. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Other viral rashes  A 1905 list of skin rashes included (1)measles, (2)scarlet fever, (3)rubella, (4)Filatow-Dukes (mild scarlet fever), and  (5)Fifth Disease: Erythema infectiosum  Human parvovirus B19 produces mild flu-like symptoms and facial rash.  Roseola  Human herpesvirus 6 causes a high fever and rash, lasting for 1-2 days, recovery leads to immunity
  30. 30. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fungal diseases of the skin and nails  Most susceptible to microbes that can resist high osmotic pressure and low moisture
  31. 31. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cutaneous Mycoses  Transmitted by contact  Dermatomycoses- colonize epidermis  Tineas (Latin for clothes moth) ringworm  Capitis-scalp, cruis-groin, pedis-foot, unguium- nails  Trichophyton: Infects hair, skin, and nails  Epidermophyton: Infects skin and nails  Microsporum: Infects hair and skin
  32. 32. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cutaneous Mycoses Figure 21.16
  33. 33. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Subcutaneous Mycoses  Caused by fungi from soil (gardeners)  Sporotrichosis  enters puncture wound then enters the lymphatic system
  34. 34. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Candidiasis  Candida albicans (yeast)  Candidiasis may result from suppression of competing bacteria by antibiotics.  Natural biota in skin; mucous membranes of genitourinary tract and mouth.  Thrush is a whitish infection of mucous membranes of mouth in infants.
  35. 35. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parasitic Infections of skin  Can infest the skin and cause disease
  36. 36. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Scabies  Sarcoptes scabiei (mite) burrows in the skin to lay eggs  intense itching  Tranmitted by intimate contact Figure 21.18
  37. 37. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pediculosis  Pediculus humanus capitis (head louse)  P. h. corporis (body louse)  Feed on blood.  Lay eggs (nits) on hair.  Tranmitted by contact Figure 21.19
  38. 38. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bacterial Diseases of the Eye  Usually originate from the skin and upper respiratory tract
  39. 39. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bacterial Diseases of the Eye  Conjunctivitis (pinkeye)  Haemophilus influenzae  Various microbes  Associated with unsanitary contact lenses  Neonatal gonorrheal ophthalmia  Neisseria gonorrhoeae  Transmitted to a newborn's eyes during passage through the birth canal.  Prevented by treatment of a newborn's eyes with antibiotics
  40. 40. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bacterial Diseases of the Eye  Inclusion conjunctivitis  Chlamydia trachomatis  Transmitted to a newborn's eyes during passage through the birth canal could lead to trachoma  Spread through swimming pool water  Trachoma (Greek word for rough)  Leading cause of blindness worldwide  Infection causes permanent scarring; scars abrade the cornea leading to blindness
  41. 41. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 21.20a Trachoma
  42. 42. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Viral Diseases of the Eye  Conjunctivitis  Transmitted by contact  Adenoviruses  Herpetic keratitis (infection of cornea)  Transmitted by contact, latent infection  Herpes simplex virus 1 (HHV-1).  Infects cornea and may cause blindness
  43. 43. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Protozoan Disease of the Eye  Acanthamoeba keratitis  Transmitted from water  Associated with unsanitary contact lenses  Mild at first, then painful

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