Exam 1 - Florell - Cutaneous Infections Flashcards
What does skin do?
Keep insides in and outsides out
-Protects from physical agents including UV light
Renewable, heals from injury
Largest sensory organ
TEMPERATURE REGULATION
What layer of the skin prevents water loss and chemical entry?
Stratum corneum
What layer repels physical insults?
Dermis
What feature of the skin protects underlying structures from injury?
Subcutaneous fat pads
___________ examination of the skin can predict histologic feature.
Clinical
_________ is a critical component in diagnosis of skin disease.
Histology
There are 4 divisions of cutaneous infections. Name them.
Bacterial
Viral
Fungal
Infestation
What are two examples of bacterial infections?
Impetigo
Folliculitis
What are three viral infections?
Herpesvirus
Molluscum contagiosum
Verruca vulgaris
What are three fungal infections?
Tinea versicolor
Tinea corporis
Deep fungal infections
What are two infestations?
Scabies
Myiasis
Normal skin flora is composed of aerobic ______, aerobic and anaerobic coryneform bacteria, gram _______ bacteria, and yeats.
Cocci
Negative
What is the most common coccus on the skin?
Staph epidermidis
What are some aerobic cocci found on skin?
S aureus
S saprophyticus
S epidermidis
Micrococcus luteus
A major function of the skin flora is the prevent skin ___________.
Infections
How does the skin prevent infections?
Ecological competition for microorganisms
Hydrolyzing lipid (sebum) produce free fatty acids which are toxic to many bacteria
Most cutaneous infections are caused by?
STAPH AUREUS
Honey yellow crusts around mouth/on face?
IMPETIGO
Impetigo involves which layers of the skin?
Epidermis
Impetigo is caused by what bacteria?
Staphylococcal (50-70%), strep, or mixed infection
What happens with impetigo?
Thin-walled vesicles become pustular and rupture (dead neutrophils) - leads to straw colored discharge that dries to form gold-yellow crusts
Treatment for impetigo?
Antibiotic ointment
Possible systemic antibiotic
What is folliculitis?
Inflammation of the hair follicle - dome-shaped pustules around hair follicles
Can be bacterial, fungal, or viral
Usually bacterial - Staph aureus is most common
Treatment of folliculitis?
Antibacterial soap
Topical or systemic antibiotics
Viruses are obligatory ____________ parasites.
Intracellular
A virus consists of what?
Central core of nucleic acid
Protein coat (capsid)
Sometimes an envelope
DNA viruses include what and what cells do they infect in the cutaneous tissue?
Herpesviruse, poxvirus, papovavirus (warts)
Infect keratinocytes
RNA viruses include what and infect what cell in the cutaneous tissue?
Retroviruses (HIV, HTLV)
Infect CD4+ T-lymphocytes
Vesicular applies developed on an erythematous base, confined to a specific dermatome?
Shingles
*Herpesvirus
**Can be confirmed with a Tzanck smear
A Tzanck smear, what is a positive result, and what is a negative result?
Positive: Multi-uncleared keratinocytes, peripheral margin inaction of chromatin (ground-glass appearance)
Negative: This is a problem, re-test ??
What is the Herpes (Varicella) Zoster?
Reactivation of varicella zoster virus (chicken pox)
-After first infection, VZV remains latent in DRG cells
Immunosuppression, and/or age risk factors = viral replication and travel down sensory nerve into skin (which means it is usually confined to a single dermatome
Symptoms of shingles?
One to several days of pain, then papules of erythema, then vesicles and crusts
Treatment: Antivirals
Describe the Herpesvirus?
DSDNA
Herpes simplex type 1 and 2
Examples: Varicella, cytomegalovirus, Epstein-Barr
Causes: Herpes labialis, genital herpes, herpetic whitlow (happens to dentists that are exposed to oral herpes), eczema herpeticum (this is one is life threatening)
Tell me about Oral Hairy Leukoplakia.
Associated with Epstein-Barr Virus
Occurs most commonly in HIV-infected patients, but can also be seen in other immunodeficiency states
Treatment: Low morbidity, no treatment necessary, but antivirals like acyclovir, valacyclovir, or famciclovir may help
What virus causes molluscum contagiosum?
Poxvirus
Who is primarily affected by the poxvirus and how is it transmitted?
Young children, sexually-active adults, systemic T-cell immunosuppression (HIV)
Transmitted by direct skin-to-skin contact, esp. if the skin is wet
How can molluscum be confirmed and what is the treatment?
HISTO - Henderson-Paterson bodies
Treatment: It resolves itself w/in 2 years
What are the following?
Verruca vulgaris?
Verruca plantaris?
Verruca plana?
Condyloma?
Common wart
Warts on balls of feet
Warts on arm
Genital warts
If a rash is scaly, what should be done?
KOH prep looking for fungal elements
What is the most common site for tinea versicolor to infect?
This is a fungus
Upper trunk is most common
*Excess heat and humidity predispose the area
Treatment: Topical or systemic antifungal agents
What does annular mean?
Having the form of a ring
Dermatophyes can only survive on what?
Dead keratin - skin or hair or nails
*Cannot survive in mouth or vagina where the startup corneum does not form
**Tx is oral or topical antifungal agents
What forms the “Mariner’s Wheel?”
Paracoccidiomycosis
What does umbilicate mean?
Having an umbilicus or navel
Central depression
What does vulgaris mean?
Being of the usual type; common
Paracoccidioidomycosis is what and how is it treated?
Deep fungal infection
- Manifestation of a systemic infection
- Introduced via puncture, abrasion, or trauma
- Types: coccidiomycosis - SW US, paracoccidoidomycosis - South America, Histoplasmosis - Central US, North American blastomycosis, etc.
**Tx - Systemic antifungal agents
Most opportunistic fungal disease is seen in pts with what?
Leukemia or other hematologic neoplasia
What is a key risk factor for invasive deep fungal infection?
Neutropenia
-Also prolonged corticosteroid therapy, and solid organ transplantation
What are some life threatening infections?
Candidiasis
Aspergillosis
**Tx - Systemic antifungal agents
What layer of the skin can scabies mites be found?
Stratum corneum
What are scabies?
Itch mite - intense itching
Oval, flat mite with dorsal spines
Female deposits eggs in stratum corneum
Contracted by contact, contaminated linens
**Tx - Permethrin 5% cream, oral ivermectin
What symptoms does scabies cause?
Popular lesions, burrows, excoriations.
Found on finger webs, wrists, hands, groins - Circle of Hebra
What is the Circle of Hebra?
Anatomic circle encompassing the axillae, elbow flexures, wrists, hands, and genital region
What is myiasis?
Infestation of human tissue by fly larvae
Most commonly caused by the human botfly - female glues eggs to the body of mosquito, stablefly, or tick
When the vector bites a human, larvae emerge and enter the puncture
Larvae grow quite large and are removed via injection and scalpel or petrolatum
