Download Body Surfaces

Chapter 26
Infections of the Body’s
Surfaces
© 2004 Wadsworth – Thomson Learning
Anatomy of the Skin
Figure 26.1
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
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
– swimmer’s ear
• otitis externa
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
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)
© 2004 Wadsworth – Thomson Learning
Bacterial Skin Infections
• Leprosy (Hansen’s 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
© 2004 Wadsworth – Thomson Learning
Varicella Zoster virus
Infection of
mucosa of
upper
respiratory
tract
Replication in
regional lymph
nodes
Replication in
liver, spleen and
other organs
Fever
Primary
viremia
Day
0
Infection of skin
and appearance of
vesicular rash
5
Incubation period
Secondary
viremia
10
15
20
Contagious period
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
Viral Infections
• Smallpox
– Eradicated worldwide in 1977
– Possible weapon of bioterrorism
– Variola: smallpox virus
• ds DNA virus
• Variola major—most virulent strain
– High fever
– Blister rash
– 50% fatality
– Vaccinia: virus used for immunization
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
Fungal Infections
• Ringworm (not a worm)
– Tinea=small insect larvae
•
•
•
•
•
tinea corporis--smooth skin
tinea pedis--athlete’s foot
tinea capatis--scalp
tinea ungulum--nails
tinea cruris--groin
– Dermatophytes
• enzymes digest keratin
© 2004 Wadsworth – Thomson Learning
Fungal Infections
• Candidiasis
– Candida albicans
•
•
•
•
•
opportunistic pathogen
infants and elderly
vagina
mouth
diaper area
© 2004 Wadsworth – Thomson Learning
Arthropod Infections
• Scabies
– Sarcoptes scabiei (mite)
– Transmission
• direct contact
• fomites
– Pathogenesis
• epidermis of human skin
• skin burrows
– Treatment
• arachnicide
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
Anatomy of the Eye
Figure 26.2
© 2004 Wadsworth – Thomson Learning
Eye infections
• Chlamydia trachomatis
• Inclusion Conjunctivitis
– infects genital tract
– transmitted during birth
• Trachoma
– keratoconjunctivitis
• blindness
– inflammation resulting in scarring
• Prevention
– sensitive to antibiotics
© 2004 Wadsworth – Thomson Learning
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
© 2004 Wadsworth – Thomson Learning
Eye infections
• Onchocerciasis (River blindness)
– Africa and Latin America
– Onchocerca volvulus
• Loaiasis (Loa Loa)
– Africa
– nematode infection of eye
© 2004 Wadsworth – Thomson Learning