Body Surfaces

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Chapter 26Infections of the Bodys Surfaces
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Anatomy of the Skin
Figure 26.1
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Bacterial Skin Infections

• Streptococcus pyogenes
• Types of infection
• depth of infection
• virulence of strain
• Impetigo
• superficial tissue
• Erysipelas
• deeper--underlying tissue
• red rash
• require treatment
• Streptococcal gangrene
• subcutaneous layer

• Virulence
• M protein
• prevents phagocytosis
• toxins
• leukocidins
• enzymes
• streptolysins
• streptokinase
• hyaluronidase

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Bacterial Skin Infections

• Staphylococcus aureus
• folliculitis
• hair follicle
• sty
• eyelash follicle
• furuncle (boil)
• inflamed, encrusted
• cellulitis
• diffuse in underlying tissue
• impetigo
• reddish, thin walled vessicles
• scalded skin syndrome
• exfoliative toxin

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Bacterial Skin Infections

• Pseudomonas aeruginosa
• opportunist organism
• pili for attachment
• extracellular slime layer
• interferes with phagocytosis
• burn patients
• blue-green pus
• folliculitis--rash
• pools and hot tubs
• swimmers ear
• otitis externa

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Bacterial Skin Infections

• Clostridium perfringens
• Gas Gangrene
• anaerobic growth
• deep wounds--necrotic tissue
• dirt-contaminated wounds
• spore in soil
• gas
• tissue blackened
• removal of tissue
• amputation

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Bacterial Skin Infections

• Acne
• small inflamed
• papules and pustules
• inflammatory disorder
• increased output of sebum
• trapped in pores
• forced in subsurface tissue
• bacteria break down sebum
• Propionibacterium acne
• Treatment
• creams remove outer layers
• antibiotics for serious cases
• isotretinoin (Accutane) (cystic acne)

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Bacterial Skin Infections

• Leprosy (Hansens Disease)
• Mycobacterium leprae
• skin and peripheral nerves
• chronic skin rash
• loss of sensation
• indeterminate leprosy
• tuberculoid leprosy
• cell-mediated response
• lepromatous leprosy
• gross disfigurement
• grows at lower temperatures
• cooler body parts
• armadillos

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Viral Infections

• Chickenpox and Shingles
• Varicella Zoster virus
• herpesvirus
• most infected by adulthood
• Pathogenesis
• upper respiratory tract
• dissemination throughout body
• incubation--10-12 days
• rash
• latency
• spinal ganglia
• Treatment--acyclovir
• Prevention--vaccine

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Varicella Zoster virus
Infection of mucosa of upper respiratory tract
Replication in regional lymph nodes
Replication in liver, spleen and other organs
Infection of skin and appearance of vesicular rash
Fever
Primary viremia
Secondary viremia
0
5
10
15
20
Day
Incubation period
Contagious period
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Viral Infections

• Gingivostomatitis and Fever blisters
• Herpes simplex virus type 1
• Pathogenesis
• vesicles of infected skin
• mucous membranes--uclers
• fluid contains virus
• Latency
• nerve cells
• reactivation
• fever, sunlight, stress

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Viral Infections

• German measles--Rubella
• prolonged exposure
• low rate of infectivity
• pathogenesis
• replication in mucosal cells
• disseminated throughout body
• rash--18 days after initial infection
• complication in pregnancy
• congenital rubella syndrome
• multiple abnormalities
• vaccine

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Viral Infections

• Measles (Rubeola)
• Measles virus
• RNA virus
• human is only reservoir
• pathogenesis
• mucosal lining of URT
• spread in lymphoid tissues
• shed respiratory tract, eye and urine
• Koplik spots
• skin rash--14 days after exposure
• vaccine
• Subacute sclerosing panencephalitis (SSPE)
• rare complication in young age

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Viral Infections

• Smallpox
• Eradicated worldwide in 1977
• Possible weapon of bioterrorism
• Variola smallpox virus
• ds DNA virus
• Variola majormost virulent strain
• High fever
• Blister rash
• 50 fatality
• Vaccinia virus used for immunization

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Viral Infections

• Papilloma virus
• 65 types of virus
• benign wart
• cervical carcinoma
• three types associated with this cancer
• one of the sexually transmitted diseases
• higher incidence in sexually active--multiple
  partners
• difficult to grow in culture
• infect specific differentiated epithelial cell

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Fungal Infections

• Ringworm (not a worm)
• Tineasmall insect larvae
• tinea corporis--smooth skin
• tinea pedis--athletes foot
• tinea capatis--scalp
• tinea ungulum--nails
• tinea cruris--groin
• Dermatophytes
• enzymes digest keratin

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Fungal Infections

• Candidiasis
• Candida albicans
• opportunistic pathogen
• infants and elderly
• vagina
• mouth
• diaper area

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Arthropod Infections

• Scabies
• Sarcoptes scabiei (mite)
• Transmission
• direct contact
• fomites
• Pathogenesis
• epidermis of human skin
• skin burrows
• Treatment
• arachnicide

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Arthropod Infections

• Pediculosis (lice)
• Pediculus humanus capitis (head louse)
• Pediculus humanus corporis (body louse)
• Transmission
• direct body contact
• fomites
• Pathogenesis
• itching
• skin breakdown and superinfection
• Treatment
• insecticides

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Anatomy of the Eye
Figure 26.2
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Eye infections

• Chlamydia trachomatis
• Inclusion Conjunctivitis
• infects genital tract
• transmitted during birth
• Trachoma
• keratoconjunctivitis
• blindness
• inflammation resulting in scarring
• Prevention
• sensitive to antibiotics

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Eye infections

• Neonatal Gonorrheal Ophthalmia
• Neisseria gonorrhoeae
• infected mother to newborn
• antibacterial treatment after birth
• Herpetic keratitis
• Herpes simplex virus
• Epidemic viral conjunctivitis (pinkeye)
• adenoviruses and enteroviruses

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Eye infections

• Onchocerciasis (River blindness)
• Africa and Latin America
• Onchocerca volvulus
• Loaiasis (Loa Loa)
• Africa
• nematode infection of eye