Dermatology Flashcards
What is the treatment for tinea versicolor?
- For limited are topical selenium sulfide, clotrimazole or ketoconazole
- For larger areas use oral itraconazole or fluconazole
What is the treatment for onychomycosis of the toenails and what is its mechanism of action?
- Terbinafine
- It inhibits squalene epoxidase, reducing fungal cell membrane ergosterol synthesis
What is the treatment for onychomycosis of the fingernails ?
- Griseofulvin
What causes tinea versicolor and how does it present?
- Caused by Malassezia furfur
- Presents as tan, brown or white scaling macular lesions that coalesce
- Usually on the chest, neck, abdomen, back or face.
- Lesions do not tan
How do you diagnose tinea versicolor?
- KOH 10% prep
- See classical “spaghetti and meatballs” referring to hyphae and spores
What is the most common cause of impetigo?
- Group A beta hemolytic Streptococcus
- Staphylococcus Aureus
What is impetigo?
- Superficial, pustular skin infection seen in children
- Limited to the epidermis and not spreading below the epidermal-dermal junction.
- Common in impoverished and crowding of children.
What are the complications of Impetigo?
- Can progress to lymphanginitis, furunculosis, or cellulitis.
- Can progress to acute glomerulonephritis but not to rheumatic fever
How do you treat impetigo?
For severe disease: - First generation cephalosporin or semisynthetic penicillin such as oxacillin, cloxacillin, dicloxacillin For mild cases: - Mupirocin, bacitracin or repatamulin For those allergic to penicillin: - Macrolides such as erythromycin or azithromycin To cover MRSA: - TMP/SMZ, clindamycin or doxycycline
What is Erysipelas?
- Bacterial infection if the deeper layer of the skin
- Involves the dermis and epidermis
- Caused by group A Streptococcus
How does Impetigo clinically present?
- More common in the arms, legs or the face.
- Begins as maculopapules and rapidly progresses to vesicular pustular lesions
- Lesions may be oozing, crusting, honey colored or draining.
How does Erysipelas clinically present?
- More likely to result in fever, chills and bacteremia.
- Bilateral shiny red, indurated edematous tender lesion on the face, arms or legs.
- Gives a bright red, angry and swollen appearance.
- Legions are sharply demarcated from normal skin
How do you treat Erysipelas?
Semisynthetic penicillin or first generation cephalosporin
Penicillin if Strep is certain
What is cellulitis?
Bacterial infection of the dermis and subcutaneous tissues with Staphylococcus and Streptococcus
How does cellulitis present?
Redness, swelling, warmth and tenderness of the skin.
No oozing, crusting, weeping or draining of the skin.
How do you treat cellulitis?
Moderate disease:
- First generation cephalosporin or semisynthetic penicillin such as oxacillin, cloxacillin or dicloxacillin
Severe disease (fever, hypotension, sepsis):
-IV oxacillin, nafcillin or cefazolin
For MRSA
- Clindamycin, TMP/SMX or Doxycycline
What causes folliculitis, furuncles and carbuncles?
- Staphylococcus infection around the hair follicle
- Can also be caused by Pseudomonas in hot tubs
What is the mechanism of action of penicillin?
- It is a beta lactam ring
- Halts peptidoglycan cell wall synthesis
- Actively binding to penicillin binding proteins, preventing removal of the terminal D-alanine and causing cell wall destruction
What is penicillin useful against?
- Streptococcus Pyogenes
- Rheumatic fever - Streptococcus viridans and Streptococcus bovis
- Left sided endocarditis - Streptococcus Agalactiae
- Given intrapartum for newborn prevention - Actinomyces Israelii
- Clostridium Perfringens
- Gangrenous lesions - Pastourelle Multocida
- Dog bites - Treponema Pallidum (Use Benzathan Penicillin G)
- Syphilis (Primary, Secondary or Early Latent) - Neisseria Meningitidis
- Only gram negative and if susceptible
What are the side effects of penicillin?
- Type I hypersensitivity
- Mediated by IgE - Drug induced autoimmune hemolytic anemia
- Positive direct Coombs test, antibodies against penicillin binding to surface of red blood cells (IgG) - Interstitial Nephritis
Mononuclear cells enter interstitum of kidney
Medication that increases squamous cell skin cancer in transplant patients?
Voriconazole
