Diseases of the Skin Flashcards
Staphylococcus aureus
[Bacterial infections of the skin]
Staphylococcus aureus- gram positive cocci, growing in clusters
Produces a number of diseases depending on the virulence factors an infecting strain carries- coagulase, clumping factor, protein A, capsule, +/- exotoxins
Can be isolated from the nares of healthy adults
S. aureus does not compete well with other organisms
Transmission: sneezing, touch, can live on the surface of fomites for long periods of time
Problem with growing antibiotic resistance- MRSA (methicillin resistant S. aureus) and VRSA (vancomycin resistant S. aureus)
Diseases caused:
Folliculitis- pimples/boils/carbuncles form due to activity of coagulase (S. aureus is coagulase positive)
Scalded Skin Syndrom-
Symptoms: red rash, sand paper texture, large blisters, peeling of the skin
Transmission: bacteria are spread from person to person
Disease only produced by strains producing exotoxin toxemia-exfoliatin
Secondary infection and loss of body fluids due to compromised innate immune system
Prevention/Treatment: Isolation, treat for antibiotic resistant bacteria
Rocky Mountain Spotted Fever
[Bacterial disease of lower alimentary tract]
Causative organism: Rickettsia- obligate intracellular, gram-negative coccobacilli
Bacteria grow in gut of tick- wood ticks or dog ticks
Organisms must migrate up from gut during process of feeding in order for bacteria to be transmitted
If remove tick before transmission of bacteria, disease can be prevented (4-10 hours)
Tick bite transmits organism into bloodstream. Bacteria then infect endothelial cells of blood stream, most evident in capillaries
Signs and symptoms: headache, muscle and joint pain, sudden onset of moderate to high fever in summer or when ticks are out
In as little as 3 days following symptoms, has DIC that starts on the extremities and works toward trunk
Involvement of heart, kidneys, and other body tissues can result in shock and death
Transmission: only through wood/dog tick bites. No human to human transmission. prevalent in SE
Treatment: tick repellents, protective clothing, careful remove of tick within 4-10 hours, treat wound with antiseptic
Early diagnosis and treatment significantly reduces mortality rate. Antibiotic treatment is vital in reducing mortality
Lyme Disease
[Bacterial disease of lower alimentary tract]
Causative agent: Borrelia burgdorferi- spirochete (Gram-negative wall that cannot be gram stained), has linear chromosome, grows in gut of deer ticks, primarily in NE and Wisconsin/Minnesota, zoonosis
Organisms must migrate up from guy during process of feeing in order for bacteria to be transmitted
If remove tick before transmission of bacteria, disease can be prevented (36 hours)
No human to human transmission
Phase one: Incubation of a few days to several weeks after bite by infected tick. Skin rash- from organisms migrating out from point of bite (Bullseye). Rash only appears 2/3 time. Symptoms: flu-like, fatigue, chills, fever, headache, stiff neck, join and muscle pains which slowly subside.
Early disseminated infection: begins about 2-8 weeks after rash appears. Electrical conduction in the heart and central nervous system is impaired. Dizzy spells or fainting. Paralysis of the face, severe headache, fatigue, which subside.
Late persistent infection: arthritis, joint pain, with swelling and tenderness of join. Symptoms happen in 60% of cases. Chronic nervous system impairments such as localized pain, paralysis and depression can occur.
Treatment: Inspect body after hiking in tick infested areas. Wear protective clothing. Tick repellent, careful removal of ticks within 36 hours. Treat wound with antiseptic. No vaccine- important to treat early with antibiotics.
Chickenpox
[Viral infections of the skin]
Varicella-zoster virus: member of the herpesvirus family, enveloped DNA virus
Symptoms: itchy bumps and blisters on face, throat and lower back, sometimes on chest and shoulders, fever
Disease may be very mild of unnoticeable in young, recovery uncomplicated
In small percentage of cases, scratching may lead to serious secondary infection by S. pyogenes or S. aureus
Most severe disease in immunocompromised individuals:
Elderly: pneumonia, tissue damage to lungs, heart, liver, kidney
Fatality rate 30% in newborns
Pregnant women: Congenital Varicella syndrome (TORCH)
-Set of diseases transmitted transplacentally that can cause a similar set of sequelae
-Deformity, nervous system damage, blindness, deafness, mental retardation, miscarriage
Transmission: Entry into respiratory system, can be spread at this point by respiratory droplets. 10-21 day incubation period (LONG).
Virus then spreads into target tissue-skin. Lesions contain infectious virus and respiratory secretions.
Reactivation results in shingles. Same virus, different disease, not as infections. After primary infection, virus becomes latent in ganglia. As a person ages, immune system becomes depressed. Virus reactivates and spreads along never, very painful. Only contact with lesions where virus is shedding transmits virus.
Treatment: Vaccine
Reye’s Syndrome
Severe complication of chicken pox or other viral infections (such as influenza) that generate a fever
Associated with use of aspirin
Measles
[Viral infections of the skin]
Causative agent: rubeola virus- enveloped RNA virus
Surface proteins: Hemagglutinin- attachment, fusion protein- fusion to host membrane and formation of giant cells
Virus replicates in cilial epithelial cells, travels to lymph nodes then to rest of body.
Incubation period of about two weeks and can be spread best prior to symptoms
Rash spreading from forehead to trunk and extremities with fever. Rash is due to immune response (T cytotoxic cell response) to infected cells
*KOPLIK’S SPOTS- red patches with white sports on oral mucosa are diagnostic
Measles suppress immune system, allows for lethal secondary infections. Pneumonia, encephalitis, secondary bacterial infections in older patients
Especially dangerous in very young or very old. Cannot vaccinate children <1yr old as immune response is not capable of dealing with attenuated virus
Treatment: MMR vaccine, attenuated vaccine
Rubella (German Measles)
[Viral infections of the skin]
Caused by rubella virus- enveloped RNA virus
Transmission: Respiratory route
Infectious ~7 days before to 7 days after rash
Symptoms: slight fever, cold symptoms, faint rash on face, chest, and abdomen.
Macular rash (from antigen/antibody complexes TYPE 3) cause smell red spots and low fever, may cause painful joints in adults
Often goes undetected. Normally self-limiting.
Virus has the ability to infect placenta of pregnant women causing Congenital rubella syndrome. TORCH. Congenital rubella syndrome is caused due to infection in the first trimester. Results in a set of severe deformities. Most severe early in pregnancy.
Vaccination aids in disease prevention- MMR (attenuated vaccine)
Dermatophytes
[Fungal infection of the skin]
Dermatophytes- fungal infections are termed mycoses
Fungi that grow on dead tissue: hair, skin, fingernails
Some diseases are caused by molds, some yeast: ring worm, athlete’s foot, jock itch, diaper rash
Smelly, itchy, ugly.
Takes a long time to resolve infection
