Lecture 13: Microbial diseases of the skin and eyes Edith Porter, M.D. 1

 Skin ▪ Anatomy of the skin ▪ Normal microbiota of the skin ▪ Terminology for skin lesions ▪ Bacterial infections of the skin ▪ Viral infections of the skin ▪ Fungal infections of the skin ▪ Parasitic infections of the skin  Eyes ▪ Anatomy of the eye ▪ Bacterial infections of the eyes ▪ Viral infections of the eyes ▪ Protozoan infections of the eyes 2

 Rigid barrier due to keratin  Antimicrobial factors  Salt  Antimicrobial peptides  Lysozyme  Fatty acids  Constant shedding  Microbial entrance typically through hair follicle and sweat glands 3

 Gram-positive bacteria  Staphylococci  Micrococci  Corynebacteria  Propionibacteria 4

Exanthem or enanthem: skin or mucosa rash arising from another focus of infection 5

 Bacterial  Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Propionibacterium acnes  Viral  Warts, small pox, chickenpox, shingles, herpes simplex, Measles, Rubella, 5 th disease, Roseola  Fungal  Candidiasis, ringworm  Parasitic  Scabies, lice, bed bugs 6

 Gram+cocci in clusters  Catalase +  Facultative anaerobe  Salt tolerant  Coagulase +  Leukocidin  Exfoliative toxin  Protein A (captures antibodies) SA PrA Y Antibody (Fc region) Golden-yellow colonies 7

 Folliculitis  Infections of hair follicles  Sty  Folliculitis of an eyelash  Furuncle (boil)  Abscess; pus surrounded by inflamed tissue  Abscess  Inflammation of tissue under the skin, accumulation of pus, walled off 8

 Also known as Ritter’s disease  Phage encoded toxin (SSST)  exfoliation  Mostly in children < 2 years  Toxemia 9

 Gram + cocci in pairs and chains  Catalase negative  Facultative anaerobe  beta-hemolytic streptococci  Group A antigen  M protein (adherence and anti-phagocytic)  Streptolysin O  Hyaluronidase  Streptokinase  DNAse  Erythrogenic toxin (phage encoded)  Responsible for red rash of scarlet fever! 10

 Localized  Erysipelas  Impetigo  Invasive  Cellulitis  Necrotizing fasciitis (flesh eating disease) 11

 Gram -negative rod  Aerobic  Oxidase +  Non-fermenter  Pyocyanin produces a blue-green pus  Pseudomonas dermatitis  Otitis externa  Post-burn infections 12

 Comedonal acne  Occurs when sebum channels are blocked by shedded cells  Inflammatory acne  Propionibacterium acnes ▪ Gram + rods ▪ Anaerobic ▪ Skin flora  Nodular cystic acne 13

 Pathogenesis  P. acnes utilizes glycerol in sebum and produces fatty acids (fermentation!)  Fatty acids are pro-inflammatory  Neutrophils are attracted further contributing to inflammation  Treatment  benzoyl peroxide (antiseptic, dries out acne lesions)  Antibiotics (erythromycin, clindamycin)  Isotretinoin (reduces sebum production, TERATOGENIC, 30% of newborns with severe damage) 14

Ischemia Loss of blood supply to tissue Necrosis Death of tissue Gangrene Death of soft tissue Gas gangrene Clostridium perfringens, gram-positive, endospore-forming anaerobic rod, grows in necrotic tissue Treatment includes surgical removal of necrotic tissue and/or hyperbaric chamber 15

 Staphylococcus aureus: pus, abscess, SSSS  Streptococcus pyogenes: impetigo, erysipela  Pseudomonas aeruginosa: Otitis externa  Propionibacterium acnes: acne  Clostridium perfringens: gangrene 16

 Skin tumors (warts)  Exanthem  Aerosol infection  viremia  skin manifestation 17

 Papillomaviruses (over 50 types in humans)  Benign skin growth  Some associated with cancer  Infection by direct contact  Treatment  Removal with ice, acid, lasers  Interferon stimulation  Interferon 18

 Smallpox (Variola)  Variola major has 20 – 30 % mortality  Variola minor has <1% mortality  Vaccination: ▪ 15/1Mio life threatening side effects ▪ 1 – 2 deaths /1 Mio  Emerging disease: Monkey pox  Orthopox virus  Only animal to human, not human to human…yet! 19

 Varicella-Zoster virus (Human herpes virus 3, HHV-3)  Initially chicken pox  Transmitted by the respiratory route, viremia, skin cell infection  Causes pus-filled vesicles on face, throat, lower back, and sometimes on chest and shoulders  Rare complications: pneumonia, encephalitis, Reye’s syndrome in conjunction with aspirin  Virus may remain latent in dorsal root ganglia  Recurrence as Shingles  Reactivation of latent HHV-3 releases viruses that move along peripheral nerves to skin  Routine vaccination 20

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 Human herpes virus 1 (HHV)  HHV-1 can remain latent in trigeminal nerve ganglia  Recurrent exacerbation  Cold sores or fever blisters (vesicles on lips)  Herpes gladiatorum (vesicles on skin)  Rare complication  Herpes encephalitis  Acyclovir may lessen symptoms 22

 Measles virus  Transmitted by respiratory route  Cold symptoms and fever  Macular rash with raised spots and Koplik's spots in oral mucosa  Rash begins on face and affects the trunk and extremities  Prevented by vaccination  Encephalitis in 1 in 1000 cases  Subacute sclerosing panencephalitis in 1 in 1,000,000 cases 23

 Rubella virus  Macular (not raised) rash and light fever  Congenital rubella syndrome causes severe fetal damage (heart, eyes, hearing, mental)  Prevented by vaccination 24

 Ranked as fifth disease in a 1905 list of skin rashes  Human parvovirus B19  Mild flu-like symptoms  Distinct skin rash  Slapped face  Fades slowly away 25

 Human herpes virus 6 and 7  Causes a high fever followed by rash lasting for 1-2 days  HHV 6 and 7 can be found in saliva in most adults 26

 Warts  Small pox  Herpes Simplex (HHV 1)  Chicken pox and shingles  Measles  Rubella  5 th Disease  Roseola 27

A 10-year-old boy presents with a fever, headaches, sore throat, and cough. He also has a macular rash on his trunk, face, and arms. A throat culture was negative for Streptococcus pyogenes. The boy most likely has: a. Streptococcal sore throat. b. Measles. c. Rubella. d. Smallpox. e. None of the above. 28

 Dermatomycoses: tinea (ringworm)  Metabolize keratin  Infect hair, nails, and outer layer of epidermidis  Treatment ▪ Topical miconazole ▪ Oral griseofulvin  Candidiasis  More often infection mucosal surfaces  Skin infection when moisture increased  Local or systemic immunosuppression  Can become systemic  Treatment ▪ Topical miconazol ▪ Systemic fluconazol 29

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 Candida albicans (yeast)  Candidiasis may result from suppression of competing bacteria by antibiotics  Occurs in skin; mucous membranes of genitourinary tract and mouth  Thrush is an infection of mucous membranes of mouth  Topical treatment with miconazole or nystatin 31

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 Scabies  Sarcoptes scabiei burrows in the skin to lay eggs  Intense local itching, superinfections  Treatment with topical insecticides 33

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 Pediculus humanus capitis (head louse)  P. h. corporis (body louse)  Feed on blood  Lay eggs (nits) on hair  Treatment with topical insecticides  Combing out  Body louse transmits typhus 35

 Small insects that feed on the blood of mammals and birds  Bite during the night, peak time before dawn  Red, itchy bites on the skin, usually in rows, no central red spot  May become superinfected  Check for bed bugs along the seams of mattresses  Wash clothes and bedding in hot, soapy water to kill bedbugs and their larvae 36 (from WebMD and cdc.gov)

37  Which of the following is responsible for severe birth defects if contracted during pregnancy? a. Measles virus b. Rubella (correct answer) c. Varicella-zoster virus d. Human parvovirus B19

 Bacterial  Haemophilus influenzae, Neisseria gonorrhoeae, Chlamydia trachomatis, Pseudomonas  Viral  Adenoviruses  Herpes simplex type 1 (HHV-1)  Protozoa  Acanthamoeba 38

 Conjunctivitis (pink eye)  Haemophilus influenzae  Various microbes  Associated with unsanitary contact lenses  Neonatal gonorrheal ophthalmia  Neisseria gonorrhoeae  Transmitted to newborn's eyes during passage through the birth canal  Prevented by treatment newborn's eyes with antibiotics 39

 Inclusion conjunctivitis  Transmitted to newborn's eyes during passage through the birth canal  Spread through swimming pool water  Treated with tetracycline  Trachoma  Greatest cause of blindness worldwide (3% of all causes)  Infection causes permanent scarring; scars abrade the cornea leading to blindness 40

1. Chronic follicular conjunctivitis 2. Inversion of eyelashes irritation of cornea 3. Corneal ulcerations, scarring 4. Vision loss typically at age 30 – 40 41

 Herpes simplex virus 1 (HHV-1)  Infects cornea  May cause blindness  Treated with trifluridine 42

Transmitted from water Associated with unsanitary contact lenses 43

 Conjunctivitis  Bacterial: Haemophilus influenzae, Neisseria gonorrhoeae, Chlamydia trachomatis, Pseudomonas aeruginosa  Viral: Adenoviruses  Keratitis  Viral: Herpes simplex type 1 (HHV-1)  Protozoal: Acanthamoeba 44

45  Using a homemade saline solution for contact lenses can result in a. Acanthamoeba keratitis b. Trachoma c. Ophthalmia neonatorum d. Inclusion conjunctivitis

 Major opportunistic pathogens causing skin lesions are staphylococci and streptococci causing infections with pus  Viral infections are often transmitted via aerosol followed by viremia and skin cell infection with a generalized exanthem  Conjunctivitis is the most common eye infection 46