MCB2004 Final Study Guide1. Describe the structure of the skin and mucous membranes, and the ways pathogens can invade the skin. Structure of the skin Epidermis (stratus comeum and keratin (water proof layer)) Dermis Secretions: perspiration and sebum Portals of entry are the follicles and ducts Subcutaneous layer Structure of the mucous membranes lines body cavities the epithelial cells are attached to an extracellular matrix (called a basement membrane) cells secrete mucus (and IgA antibodies) some cells have cilia (trap microbes and move things along the tract)2. Provide examples of normal skin microbiota, and state the general locations and ecological roles of its members. Normal flora Gram positive bacteria (on the skin) Staphylococcus Streptococcus Diphteroids (coryneforms) (normally hair follicles (acne) like oil) Micrococci Yeats (cause dandruff) (on the skin) Roles The secrete byproducts that make it hard for pathogens to live and they cause competition of nutrients for pathogens.3. Differentiate Staphylococci from Streptococci, and name several skin infections caused by each. Staphylococci Secretes coagulase Folliculitis (infection of the hair follicles), sty (folliculitis of an eyelash), furuncle (abscess, pus surrounded by inflamed tissue), carbuncle (inflammation of tissue under the skin), impetigo (isolated pustules of the newborn), toxemia (occur when toxins enter bloodstream; scalded skin syndrome (causes the body to have the skin peel off in layers), toxic shock syndrome (toxic is released into your body) Streptococci Hemolytic enzymes Streptpkinases, hyaluronidase, exotoxin A (super antigen, causes the immune system to hurt the host because of enzymes released), cellulitis, necrotizing fascilitis (flesh eating, cause severe and rapid tissue damage)4. List the causative agent, mode of transmission, and clinical symptoms of Pseudomonas dermatitis, otitis externa, and acne. Causative agent: Dermatitis (self limiting, 2 weeks), swimming pool, sauna, hot tub Wound and skin infections Otitis externa (swimmers ear) Burn patient infections Mode of transmission: person to person Clinical symptoms Dermatitis: rash, red bumps, itching, dry red patches, and blisters Otitis externa: mainly ear pain Acne: bumps typically on your face, neck, and back where the glands are5. List the causative agent, mode of transmission, and clinical symptoms of these skin infections: warts, smallpox, chickenpox, shingles, cold sores, measles, rubella. Warts Causative agent: herpes simplex virus Mode of transmission: sexual contact or birth Clinical symptoms: cauliflower-like papules or small slightly elevated pink or tan flat topped papules Smallpox Causative agent: Chicken pox Causative agent: herpesvirus Mode of transmission: person to person contact or droplets Clinical symptoms: red dots all over the body, itchy Shingles Causative agent: reactivation of the chickenpox virus Mode of transmission: none Clinical symptoms: pain, numbness, tingling, a red rash after the pain, itching usually in one area of the body. Cold sores Measles Causative agent: measles virus (paramyxovirus) Mode of transmission: respiratory route Clinical symptoms: macular rash and Koplik’s spots ( small red spots with blue-white center) Rubella Causative agent: rubella virus (togavirus) Mode of transmission: Clinical symptoms: macular rash and light fever6. Define conjunctivitis. Inflammation of the conjunctiva 7. List the causative agent, mode of transmission, and clinical symptoms of these eye infections: neonatal gonorrheal ophthalmia, inclusion conjunctivitis, trachoma, and herpetic keratitis. Neonatal gonorrheal ophthalmia Causative agent: neisseria gonorrheae Mode of transmission: birth Clinical symptoms: pus in the eyes Inclusion conjunctivitis Causative agent: Chlamydia trachomatis Mode of transmission: birth Clinical symptoms: reddened eyes, tearing with mucus Trachoma Causative agent: Chlamydia trachomatis Mode of transmission: flies and birth Clinical symptoms: mild itching and irritation of the eyes and eyelids, discharge of mucus from the eyes Herpetic keratitis Causative agent: herpes simplex virus 1 Mode of transmission: corneal transplantation, direct contact with the eye Clinical symptoms: photophobia (sensitivity to light), epiphora (overflow of tears), uveitis (inflammation of the middle layer of the eye), blurred vision.8. Define central nervous system and blood-brain barrier. The central nervous system consists of the brain and spinal cord. It is also the control center for the entire body. The blood-brain barrier: certain capillaries permit some substances to pass from the blood into the brain but restrict other. Drugs can only pas this if the y are lipid soluble but inflammation of the brain allows drugs that are not lipid soluble to enter.9. Differentiate meningitis from encephalitis. Meningitis: inflammation of the meninges Encephalitis: inflammation of the brain10. Discuss meningitis caused by Haemophilus influenzae, Neisseria meningitides, Streptococcus pneumoniae, and Listeria monocytogenes. Haemophilus influenza: Occurs mostly in children ( mos to 4 yrs) Gram-neg aerobic bacteria, normal throat microbiota CHO capsule antigen type B Prevented by Hib vaccine Neisseria meningitis: gram-neg aerobic cocci with a capsule made of polysaccharide 10% of people are healthy nasopharyngeal carriers (nose and throat) Begins as throat infection, rash Vaccination recommended for college students The carriers are the reservoir of infection Rash doesn’t fade when pressed Streptococcus pneumonia Gram-pos cocci 70% of people are healthy nasopharyngeal cariers Most common in children (1 mos to 4 yrs) Mortality: 30% in children, 80% in elderly Prevented by vaccination Listeria monocytogenes Gram-pos aerobic rod Usually foodborne, it can be transmitted to fetus and cause spontaneous abortion and still birth Reproduce in phagocytes esp in the liver and can jump to nearby phagocytes Two forms : infected adults and infection of the fetus and newborn11. Explain how bacterial meningitis is diagnosed and treated. Diagnosed: need cerebrospinal fluid to confirm Treated: antibiotics: gen-amp and 3rd
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