Microbial Diseases of the Skin and Eyes

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Microbiology, an introduction. Basics microbiology, specially diseases caused by bacteries and virus

Microbiology, an introduction. Basics microbiology, specially diseases caused by bacteries and virus

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  • 1. Chapter 21 Microbial Diseases of the Skin and EyesCopyright © 2010 Pearson Education, Inc. Lectures prepared by Christine L. Case
  • 2. Q&A  How does the morphology of Candida albicans contribute to the microbe’s pathogenicity?Copyright © 2010 Pearson Education, Inc.
  • 3. Structure and Function of the SkinLearning Objective 21-1 Describe the structure of the skin and mucous membranes and the ways pathogens can invade the skin.Copyright © 2010 Pearson Education, Inc.
  • 4. The Structure of Human Skin Perspiration and sebum contain nutrients Salt inhibits microbes Lysozyme hydrolyzes peptidoglycan Fatty acids inhibit some pathogensCopyright © 2010 Pearson Education, Inc. Figure 21.1
  • 5. Mucous Membranes Line body cavities The epithelial cells are attached to an extracellular matrix Cells secrete mucus Often acidic Some cells have cilia In eyes, washed by tears with lysozymeCopyright © 2010 Pearson Education, Inc.
  • 6. Check Your Understanding The moisture provided by perspiration encourages microbial growth on the skin. What factors in perspiration discourage microbial growth? 21-1Copyright © 2010 Pearson Education, Inc.
  • 7. Normal Microbiota of the SkinLearning Objective 21-2 Provide examples of normal skin microbiota, and state the general locations and ecological roles of its members.Copyright © 2010 Pearson Education, Inc.
  • 8. Normal Microbiota of the Skin Gram-positive, salt-tolerant bacteria  Staphylococci  Micrococci  DiphtheroidsCopyright © 2010 Pearson Education, Inc. Figure 14.1a
  • 9. Normal Microbiota of the Skin Grow on oils Aerobes on surface  Corynebacterium xerosis Anaerobes in hair follicles  Propionibacterium acnes Yeast  Malassezia furfurCopyright © 2010 Pearson Education, Inc.
  • 10. Check Your Understanding Are skin bacteria more likely to be gram-positive or gram-negative? 21-2Copyright © 2010 Pearson Education, Inc.
  • 11. Microbial Diseases of the Skin Exanthem: Skin rash arising from another focus of the infection Enanthem: Mucous membrane rash arising from another focus of the infectionCopyright © 2010 Pearson Education, Inc.
  • 12. Skin LesionsCopyright © 2010 Pearson Education, Inc. Figure 21.2
  • 13. Bacterial Diseases of the SkinLearning Objectives21-3 Differentiate staphylococci from streptococci, and name several skin infections caused by each.21-4 List the causative agent, mode of transmission, and clinical symptoms of Pseudomonas dermatitis, otitis externa, acne, and Buruli ulcer.Copyright © 2010 Pearson Education, Inc.
  • 14. Staphylococcal Skin Infections Staphylococcus epidermidis  Gram-positive cocci, coagulase-negative Staphylococcus aureus  Gram-positive cocci, coagulase-positiveCopyright © 2010 Pearson Education, Inc. Clinical Focus, p. 593
  • 15. Staphylococcus aureus Antibiotic resistant Leukocidin Resists opsonization Survives in phagolysosome Lysozyme resistant Exfoliative toxin SuperantigenCopyright © 2010 Pearson Education, Inc. Clinical Focus, p. 593
  • 16. Staphylococcal BiofilmsCopyright © 2010 Pearson Education, Inc. Figure 21.3
  • 17. 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 Impetigo: crusting (nonbullous) sores, spread by autoinoculationCopyright © 2010 Pearson Education, Inc.
  • 18. Nonbullous Lesions of ImpetigoCopyright © 2010 Pearson Education, Inc. Figure 21.4
  • 19. Scalded Skin Syndrome Toxic shock syndrome (TSS)  Toxic shock syndrome toxin 1 Scalded skin syndrome  Bullous impetigo  Impetigo of the newbornCopyright © 2010 Pearson Education, Inc.
  • 20. Lesions of Skin SyndromeCopyright © 2010 Pearson Education, Inc. Figure 21.5
  • 21. Streptococcal Skin Infections Streptococcus pyogenes Group A beta-hemolytic streptococci Hemolysins Hyaluronidase Stretolysins M proteinsCopyright © 2010 Pearson Education, Inc.
  • 22. Group A Beta-Hemolytic StreptococciCopyright © 2010 Pearson Education, Inc. Figure 21.6
  • 23. Streptococcal Skin Infections Necrotizing fasciitis ErysipelasCopyright © 2010 Pearson Education, Inc. Figure 21.7
  • 24. Invasive Group A StreptococcalInfections Exotoxin A, superantigenCopyright © 2010 Pearson Education, Inc. Figure 21.8
  • 25. Streptococcal Toxic Shock Syndrome M proteins Complex with fibrinogen Binds to neutrophils Activates neutrophils Release of damaging enzymes Shock and organ damageCopyright © 2010 Pearson Education, Inc.
  • 26. Infections by Pseudomonads Pseudomonas aeruginosa  Gram-negative, aerobic rod  Pyocyanin produces a blue-green pus Pseudomonas dermatitis Otitis externa, or “swimmer’s ear” Post-burn infections OpportunisticCopyright © 2010 Pearson Education, Inc.
  • 27. Buruli Ulcer Caused by Mycobacterium ulcerans Deep, damaging ulcers Exceeds incidence of leprosyCopyright © 2010 Pearson Education, Inc.
  • 28. Classifications of Acne Comedonal (mild) acne Inflammatory (moderate) acne Nodular cystic (severe) acneCopyright © 2010 Pearson Education, Inc.
  • 29. Comedonal Acne Mild  Sebum channels blocked with shed cells Treatment  Topical agents  Salicyclic acid preparations  Retinoids  AdapaleneCopyright © 2010 Pearson Education, Inc.
  • 30. Inflammatory Acne Propionibacterium acnes  Gram-positive, anaerobic rod Treatment  Preventing sebum formation (isotretinoin)  Antibiotics  Benzoyl peroxide to loosen clogged follicles  Visible (blue) light (kills P. acnes)Copyright © 2010 Pearson Education, Inc.
  • 31. Nodular Cystic Acne Severe Treatment  IsotretinoinCopyright © 2010 Pearson Education, Inc. Figure 21.9
  • 32. Check Your Understanding Which bacterial species features the virulence factor M protein? 21-3 What is the common name for otitis externa? 21-4Copyright © 2010 Pearson Education, Inc.
  • 33. Viral Diseases of the SkinLearning Objective21-5 List the causative agent, mode of transmission, and clinical symptoms of these skin infections: warts, smallpox, monkeypox, chickenpox, shingles, cold sores, measles, rubella, fifth disease, and roseola.Copyright © 2010 Pearson Education, Inc.
  • 34. Warts Papillomaviruses  Treatment − Removal − Cryotherapy − Electrodesiccation − Salicylic acid − Imiquimod (stimulates interferon production) − BleomycinCopyright © 2010 Pearson Education, Inc.
  • 35. Poxviruses Smallpox (variola)  Smallpox virus (orthopox virus) − Variola major has 20% mortality − Variola minor has <1% mortality  Eradicated by vaccination Monkeypox  Prevention by smallpox vaccinationCopyright © 2010 Pearson Education, Inc.
  • 36. Smallpox LesionsCopyright © 2010 Pearson Education, Inc. Figure 21.10
  • 37. Chickenpox Varicella-zoster virus (human herpesvirus 3) Transmitted by the respiratory route Causes pus-filled vesicles Virus may remain latent in dorsal root ganglia Prevention: Live attenuated vaccine Breakthrough varicella in vaccinated peopleCopyright © 2010 Pearson Education, Inc.
  • 38. Copyright © 2010 Pearson Education, Inc. Figure 21.11a
  • 39. Shingles Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin Postherpetic neuralgia Prevention: Live attenuated vaccine Acyclovir may lessen symptomsCopyright © 2010 Pearson Education, Inc.
  • 40. Copyright © 2010 Pearson Education, Inc. Figure 21.11b
  • 41. Herpes Simplex Human herpesvirus 1 (HSV-1) and 2 (HSV-2) Cold sores or fever blisters (vesicles on lips) Herpes gladiatorum (vesicles on skin) Herpetic whitlow (vesicles on fingers) Herpes encephalitis HSV-1 can remain latent in trigeminal nerve gangliaCopyright © 2010 Pearson Education, Inc.
  • 42. Cold Sores Caused by Herpes SimplexVirusCopyright © 2010 Pearson Education, Inc. Figure 21.12
  • 43. HSV-1 in the Trigeminal Nerve GanglionCopyright © 2010 Pearson Education, Inc. Figure 21.13
  • 44. Herpes Simplex HSV-2 can remain latent in sacral nerve ganglia HSV-2 encephalitis: 70% fatality Encephalitis treatment: AcyclovirCopyright © 2010 Pearson Education, Inc.
  • 45. Measles (Rubeola) Measles virus Transmitted by respiratory route Macular rash and Kopliks spots Prevented by vaccinationCopyright © 2010 Pearson Education, Inc. Figure 21.14
  • 46. Measles (Rubeola) Encephalitis in 1 in 1,000 cases Subacute sclerosing panencephalitis in 1 in 1,000,000 casesCopyright © 2010 Pearson Education, Inc.
  • 47. Reported U.S. Cases of Measles, 1960–2007Copyright © 2010 Pearson Education, Inc. Clinical Focus, p. 505
  • 48. Rubella (German Measles) Rubella virus Macular rash and fever Congenital rubella syndrome causes severe fetal damage Prevented by vaccinationCopyright © 2010 Pearson Education, Inc. Figure 21.15
  • 49. Fifth Disease Name derived from a 1905 list of skin rashes, which included  1. Measles  2. Scarlet fever  3. Rubella  4. Filatov Dukes disease (mild scarlet fever), and  5. Fifth disease, or erythema infectiosum − Human parvovirus B19 produces mild flu-like symptoms and facial rashCopyright © 2010 Pearson Education, Inc.
  • 50. Roseola Caused by human herpesvirus 6 (HHV-6) and 7 (HHV-7) High fever and rash lasting for 1–2 daysCopyright © 2010 Pearson Education, Inc.
  • 51. Check Your Understanding How did the odd designation of “fifth disease” arise? 21-5Copyright © 2010 Pearson Education, Inc.
  • 52. Diseases in Focus: Macular Rashes  A 4-year-old boy with a history of cough, conjunctivitis, and fever (38.3°C) now has a macular rash that starts on his face and neck and is spreading to the rest of his body.  Can you identify infections that could cause these symptoms?Copyright © 2010 Pearson Education, Inc.
  • 53. Diseases in Focus:Vesicular and Pustular Rashes  An 8-year-old boy has a rash consisting of vesicular lesions of 5 days’ duration on his neck and stomach. Within 5 days, 73 students in his elementary school had illness matching the case definition for this disease.  Can you identify infections that could cause these symptoms?Copyright © 2010 Pearson Education, Inc.
  • 54. Fungal Diseases of the Skin and NailsLearning Objectives21-6 Differentiate cutaneous from subcutaneous mycoses, and provide an example of each.21-7 List the causative agent and predisposing factors for candidiasis.Copyright © 2010 Pearson Education, Inc.
  • 55. Cutaneous Mycoses Dermatomycoses  Also known as tineas or ringworm  Metabolize keratinCopyright © 2010 Pearson Education, Inc.
  • 56. DermatomycosesCopyright © 2010 Pearson Education, Inc. Figure 21.16
  • 57. Cutaneous Mycoses Genera of fungi involved  Trichophyton: Infects hair, skin, and nails  Epidermophyton: Infects skin and nails  Microsporum: Infects hair and skin Treatment  Topical miconazole  Topical allylamineCopyright © 2010 Pearson Education, Inc.
  • 58. Cutaneous Mycoses Tinea unguium Treatment  Itraconazole  TerbinafineCopyright © 2010 Pearson Education, Inc.
  • 59. Subcutaneous Mycoses More serious than cutaneous mycoses Sporotrichosis  Most common U.S. disease of this type  Sporothrix schenchii enters puncture wound  Treated with potassium iodide (KI)Copyright © 2010 Pearson Education, Inc.
  • 60. Candidiasis Candida albicans (yeast) Candidiasis may result from suppression of competing bacteria by antibiotics Occurs in skin and mucous membranes of genitourinary tract and mouth Thrush: An infection of mucous membranes of mouth Topical treatment with miconazole or nystatinCopyright © 2010 Pearson Education, Inc.
  • 61. Candida albicansCopyright © 2010 Pearson Education, Inc. Figure 21.17a
  • 62. Case of Oral CandidiasisCopyright © 2010 Pearson Education, Inc. Figure 21.17b
  • 63. Systemic Candidiasis Fulminating disease can result in immunosuppressed individuals Treatment: FluconazoleCopyright © 2010 Pearson Education, Inc.
  • 64. Q&A  How does the morphology of Candida albicans contribute to the microbe’s pathogenicity?Copyright © 2010 Pearson Education, Inc.
  • 65. Check Your Understanding How do sporotrichosis and athlete’s foot differ? In what ways are they similar? 21-6 How might the use of penicillin result in a case of candidiasis? 21-7Copyright © 2010 Pearson Education, Inc.
  • 66. Parasitic Infestation of the SkinLearning Objective21-8 List the causative agent, mode of transmission, clinical symptoms, and treatment for scabies and pediculosis.Copyright © 2010 Pearson Education, Inc.
  • 67. Scabies Sarcoptes scabiei burrows in the skin to lay eggs Treatment with topical insecticidesCopyright © 2010 Pearson Education, Inc. Figure 21.18
  • 68. Pediculosis (Lice) Pediculus humanus capitis (head louse) P. h. corporis (body louse)  Feed on blood  Lay eggs (nits) on hair  Treatment with topical insecticidesCopyright © 2010 Pearson Education, Inc. Figure 21.19
  • 69. Check Your Understanding What diseases if any, are spread by head lice, such as Pediculus humanus capitis? 21-8Copyright © 2010 Pearson Education, Inc.
  • 70. Diseases in Focus:Patchy Redness and Pimple-Like Conditions  An 11-month-old boy came to clinic with a 1-week history of an itchy red rash under his arms. He seemed more bothered at night and had no fever.  Can you identify infections that could cause these symptoms?Copyright © 2010 Pearson Education, Inc.
  • 71. Microbial Diseases of the EyeLearning Objectives 21-9 Define conjunctivitis. 21-10 List the causative agent, mode of transmission, and clinical symptoms of these eye infections: ophthalmia neonatorum, inclusion conjunctivitis, trachoma. 21-11 List the causative agent, mode of transmission, and clinical symptoms of these eye infections: herpetic keratitis, Acanthamoeba keratitis.Copyright © 2010 Pearson Education, Inc.
  • 72. Bacterial Diseases of the Eye Conjunctivitis  An inflammation of the conjunctiva  Also called pinkeye or red eye  Commonly caused by Haemophilus influenzae  Various other microbes can also be the cause  Associated with unsanitary contact lensesCopyright © 2010 Pearson Education, Inc.
  • 73. Bacterial Diseases of the Eye Ophthalmia neonatorum  Caused by Neisseria gonorrhoeae  Transmitted to a newborns eyes during passage through the birth canal  Prevented by treating a newborns eyes with antibioticsCopyright © 2010 Pearson Education, Inc.
  • 74. Bacterial Diseases of the Eye Chlamydia trachomatis  Causes inclusion conjunctivitis, or chlamydial conjunctivitis  Transmitted to a newborns eyes during passage through the birth canal  Spread through swimming pool water  Treated with tetracyclineCopyright © 2010 Pearson Education, Inc.
  • 75. Bacterial Diseases of the Eye Chlamydia trachomatis  Causes trachoma  Leading cause of blindness worldwide  Infection causes permanent scarring; scars abrade the cornea leading to blindnessCopyright © 2010 Pearson Education, Inc.
  • 76. TrachomaCopyright © 2010 Pearson Education, Inc. Figure 21.20a
  • 77. TrachomaCopyright © 2010 Pearson Education, Inc. Figure 21.20b
  • 78. Other Infectious Diseases of the Eye Keratitis  Inflammation of the cornea  Bacteria (U.S.)  Fusarium and Aspergillus (Africa and Asia)Copyright © 2010 Pearson Education, Inc.
  • 79. Other Infectious Diseases of the Eye Herpetic keratitis  Caused by herpes simplex virus 1 (HSV-1).  Infects cornea and may cause blindness  Treated with trifluridineCopyright © 2010 Pearson Education, Inc.
  • 80. Other Infectious Diseases of the Eye Acanthamoeba keratitis  Transmitted via water  Associated with unsanitary contact lensesCopyright © 2010 Pearson Education, Inc.
  • 81. Check Your Understanding What is the common name of inclusion conjunctivitis? 21-9 Why have antibiotics almost entirely replaced the less expensive use of silver nitrate for preventing ophthalmia neonatorum? 21-10 Of the two eye diseases herpetic keratitis and Acanthamoeba keratitis, which is the more likely to be caused by an organism actively reproducing in saline solutions for contact lenses? 21-11Copyright © 2010 Pearson Education, Inc.
  • 82. Diseases in Focus:Microbial Diseases of the Eye  A 20-year-old man had eye redness with dried mucus crust in the morning. The condition resolved with topical antibiotic treatment.  Can you identify infections that could cause these symptoms?Copyright © 2010 Pearson Education, Inc.