Infectious Rashes Flashcards
What are cold sores?
Contagious, recurrent blisters that spread by direct contact with mucosal surface or blister itself
Cold sores are primarily caused by herpes simplex virus (HSV).
What causes orofacial cold sores?
HSV 1
Orofacial cold sores typically appear on the mouth and face.
What causes genital cold sores?
HSV 2
Genital cold sores are less common than orofacial sores.
What are the initial symptoms of cold sores?
Tingling or burning sensation
This sensation is often followed by the formation of blisters.
What is the typical presentation of cold sores?
Blisters form in clusters on erythematous skin and crust over several days
The blisters are painful to touch.
How is cold sore infection confirmed?
Clinical diagnosis, Tzanck smear, or viral swab test
These methods help confirm HSV infection.
What is the typical management for oral herpes?
Usually self-limiting
Oral herpes typically resolves without intervention.
What is the treatment for genital herpes?
Topical 5% acyclovir ointment (200 mg 5x daily for 5 days)
Acyclovir is an antiviral medication effective against HSV.
What are the second-line drugs for genital herpes?
Famciclovir, valacyclovir
These can be used if acyclovir is not effective or tolerated.
What is the prophylactic treatment for herpes recurrence?
200 mg TDS for 6-12 months
This prophylactic treatment aims to prevent recurrence of herpes.
What is the prognosis for cold sores?
Cold sores are recurrent as HSV persists in sensory ganglia, but can be more chronic in immunocompromised patients.
Complications include erythema multiforme, eczema herpeticum, and affects CNS as it affects temporal lobe (memory loss).
What is eczema herpeticum?
Eczema herpeticum is a complication of herpes infections that can occur in individuals with eczema.
What is herpes zoster/shingles?
Herpes zoster/shingles is a painful rash on one side of the body in a dermatomal/band pattern, caused by reactivation of the latent varicella-zoster virus in the sensory ganglia (patient previously had chicken pox).
How is the rash from herpes zoster presented?
The rash is distributed in one or multiple adjacent dermatomes or in bands and doesn’t cross the midline.
The rash has clustered, crusting vesicles on an erythematous base.
What are systemic symptoms associated with shingles?
Systemic symptoms include fever and malaise.
What investigations are used for herpes zoster?
Investigations include scrape test or viral culture from blisters, Tzanck smear, and Direct fluorescent antibody (DFA) assays which are used to detect VZV.
What characterizes the rash in shingles?
Rash distributed in one/multiple adjacent dermatomes or in bands and doesn’t cross midline.
Rash has clustered, crusting vesicles on erythematous base.
What systemic symptoms may accompany shingles?
Systemic symptoms include fever and malaise.
What investigations are used to detect VZV?
Scrape test or viral culture from blisters, tzanck smear, Direct fluorescent antibody (DFA) assays.
These tests are used to detect VZV.
What is the management for shingles?
Acyclovir 800 mg 5x daily for 5 days in the week.
Most effective if taken within 24-72 hrs after onset. Can also prescribe analgesics.
What is the prognosis for shingles?
Should resolve in 2-3 weeks, but if untreated, it can lead to post-herpetic neuralgia and cranial nerve syndromes.
What are the characteristics of molluscum contagiosum?
Benign, self-limiting papules with a central dimple caused by molluscum contagiosum virus (MCV).
MCV spreads by skin-skin contact and is most common in children and sexually-active adults.
What is the presentation of molluscum contagiousum?
Skin-coloured and dome-shaped pearly papules with a central dot/dimple, containing a kerotic (cheesy) plug.
Is further investigation necessary for molluscum contagiousum?
No other investigations are necessary, but consider testing for HIV if the patient is otherwise completely healthy.
What is the management for the molluscum contagiousum if it does not resolve spontaneously?
Cryotherapy and curettage.
What is impetigo?
A common, contagious bacterial infection of the superficial layers of the epidermis.
What causes impetigo?
Caused by staphylococcus aureus and streptococcus pyogenes (Group A strep) transmission in the natural flora.
Who is most commonly affected by impetigo?
Most common in young children.
What are the two types of impetigo?
- Nonbullous impetigo
- Bullous impetigo.
What is the presentation of nonbullous impetigo?
Erythematous papules that rapidly evolve into vesicles and pustules that rupture, forming golden-yellow crusting.
Mostly on face.
What is bullous impetigo?
Bullous impetigo is characterized by flaccid bullae (large blisters) on non-erythematous skin that burst and ooze yellow fluid, which crusts over and leaves a scaly rim.
Usually found in skinfolds such as the trunk, axilla, groin, between buttocks, and between digits.
How is bullous impetigo diagnosed?
Bullous impetigo is diagnosed clinically.
What is the management for bullous impetigo?
Management includes topical antibiotics applied 3 times daily for 7-10 days, such as Mupirocin, retapamulin, and fusidic acid.
Systemic antibiotics are prescribed for all cases of bullous impetigo and for non-bullous impetigo with specific conditions.
What are the first-line and second-line systemic antibiotics for bullous impetigo?
First-line: Flucloxacillin; Second-line: Clarithromycin, erythromycin (for pregnancy).
What is folliculitis?
Folliculitis is an infection of hair follicles associated with staphylococcus aureus or exposure to pseudomonas aeruginosa in contaminated hot water.
It usually presents as asymptomatic but can be pruritic and painful, appearing as erythematous papules pierced by a central hair.
What is Furunculosis?
Deep infection of the hair follicle leading to abscess formation with accumulation of pus and necrotic tissue.
Tender, brightly erythematous, fluctuant, smooth nodules that rupture with purulent discharge; commonly found on the face, back of the neck, armpits, thighs, and buttocks.
What are the characteristics of Carbunculosis?
Rapid/simultaneous formation of many carbuncles (clusters of boils connected under the skin).
Erythematous, tender, inflamed nodules with multiple draining sinus tracts or pustules on the surface; presents on neck, back, thighs, and with systemic symptoms.
How is Furunculosis diagnosed?
Clinical diagnosis that can be confirmed with culture of pus drainage.
What is the management for Furunculosis?
Topical 1% clindamycin or 2% erythromycin; systemic antistaphylococcal antibiotics like vancomycin; incision and drainage for large boils.
What is Ecthyma?
Deep ulcerative skin infection that penetrates down to the dermis, caused by staphylococcus aureus and streptococcus pyogenes (Group A strep) transmission in the natural flora.
What is the presentation of Ecthyma?
Vesicles and bullae that become punched-out ulcers with well-defined edges and higher surrounding tissues, accompanied by adherent crust, which leads to scarring after the eschar falls off.
How is Ecthyma diagnosed?
Clinical diagnosis, can be confirmed with bacterial culture.
What is the management for Ecthyma?
Oral antistaphylococcal antibiotics.
What causes scabies?
Scabies is caused by Sarcoptes scabiei var. hominis (human itch mite) burrowing into the epidermis.
How is scabies transmitted?
Scabies is transmitted by skin-to-skin contact.
What are common presentations of scabies?
Common presentations include vesicles, papules, pustules, and burrows.
Where on the body does scabies usually appear?
Scabies usually appears in finger webs, around the wrists, elbows, armpits, waist, thighs, genitalia, nipples, breasts, and lower buttocks (everywhere except head and neck).
What symptom is associated with scabies?
Intense pruritus all over the body, especially at night.
What does a scabies burrow look like?
A scabies burrow appears as tiny raised serpiginous lines that are greyish or skin-coloured.
How is scabies diagnosed?
Scabies is diagnosed through microscopy of skin scrapings to see mites and eggs.
What is the first-line treatment for scabies?
The first-line treatment for scabies is 5% permethrin cream.
What is the second-line treatment for scabies?
The second-line treatment for scabies is 0.5% malathion lotion.
How should scabies treatment be applied?
The treatment should be applied by the patient and family members all over the body.
When should scabies treatment be repeated?
Scabies treatment should be repeated 7 days later.
What is Oriental sore/Cutaneous leishmaniasis (CL)?
A skin infection caused by the leishmania tropica parasite transmitted by a sand fly, characterised by erythema and ulceration.
What is Mucocutaneous leishmaniasis/Espundia (MCL)?
A skin infection caused by the leishmania braziliensis parasite transmitted by a sand fly, characterised by ulcerative lesions in the nose, mouth, and throat.
What is Diffuse cutaneous leishmaniasis (DCL)?
A skin infection caused by leishmania mexicana and leishmania ethiopia parasites transmitted by a sand fly, characterised by nodules and plaques that cover most of the body and become ulcers.
How is leishmaniasis investigated?
Through clinical diagnosis and parasite culture.
What is the management for Cutaneous leishmaniasis (CL)?
It is self-limiting but antibiotics can be prescribed.
What is the management for Mucocutaneous leishmaniasis (MCL) and Diffuse cutaneous leishmaniasis (DCL)?
Antiparasitic drugs such as Amphotericin and pentavalent antimonials.
What is Cutaneous Larva Migrans?
A parasitic skin infection caused by penetration of hookworm larvae that affect dogs and cats.
How is Cutaneous Larva Migrans transmitted?
By walking barefoot on sandy beaches or moist faeces-contaminated soil.
What are the typical presentations of Cutaneous Larva Migrans?
Erythematous, serpiginous lesions that lengthen by several mm per day with allergic reaction and pruritus.
How is Cutaneous Larva Migrans investigated?
Clinical diagnosis and travelling history of the patient.
What is the first-line management for Cutaneous Larva Migrans?
Antihelminthic/parasiticide such as topical/oral thiabendazole.
What are alternative treatments for Cutaneous Larva Migrans?
Albendazole and mebendazole.
What antibiotics can be used to treat secondary infections in Cutaneous Larva Migrans?
Ivermectin.
What is Tinea?
A fungal skin infection caused by Tinea verrucosum, Trichophyton rubrum, and Microsporum canis.
What are the types of Tinea?
Tinea Capitis (head), Tinea Corporis (ringworm), Tinea Pedis (feet), Tinea Unguium (fungal nail), Tinea Cruris (groin), Tinea/Pityriasis versicolor.
What is the presentation of Tinea?
Scaly discoid (ring-shaped) lesions that are red, silver, or darker than skin tone, and can have clearing/paler centres.
Where is Tinea commonly distributed?
Commonly on scalp, face, trunk, arms, legs, and nails.
What symptom is associated with Tinea?
Pruritus.
What investigation is used for Tinea?
Skin scrape test will show microscopic branching hyphae; Wood’s light (long-wave UV light) shows green fluorescence.
What is the management for Tinea?
Topical antifungal medications from imidazole drug class (e.g., Miconazole, clotrimazole) or allylamine drug class (e.g., Terbinafine).
Systemic antifungals (e.g., Griseofulvin, terbinafine, itraconazole) are used for nails, scalp, widespread, and chronic infections.
What is candidal intertrigo?
A superficial yeast infection of skin folds, mostly caused by Candida albicans but can also be caused by C. glabrata, C. krusei, C. tropicalis, C. auris.
What are the common presentations of candidal intertrigo?
Erythematous patches on both sides of skin fold, which can progress to erosion, fissures, weeping, and maceration.
Where does candidal intertrigo commonly occur?
In areas where moisture can get trapped, such as interdigital areas, creases, abdominal folds, behind the ear, neck creases, under the breast, and perineum.
What symptoms are associated with candidal intertrigo?
Causes pruritus and pain.
How is candidal intertrigo investigated?
Through a skin scrape test or fungal swab/culture.
What predisposing conditions can lead to widespread intertrigo?
Conditions such as diabetes and HIV.
What is the management for candidal intertrigo?
Topical antifungal medications from the imidazole drug class (e.g., Miconazole, clotrimazole) or allylamine drug class (e.g., Terbinafine), or antifungal with weak steroid (e.g., daktacort).
What is the treatment for severe candidal intertrigo?
Oral antifungals such as fluconazole.
What lifestyle changes can help manage candidal intertrigo?
Patients should wear loose clothing, lose weight if obese, and use powder to keep skin folds dry.
Which strains of Candida can be multi-drug resistant?
C. krusei and C. auris strains.
What is superficial candidiasis?
A fungal infection of the mouth, vagina, or skin that causes white or red patches and itching, mostly caused by Candida albicans but can also be caused by C. glabrata, C. krusei, C. tropicalis, C. auris.
What are common risk factors for superficial candidiasis?
Antibiotics, diabetes, pregnancy, and malnutrition.
What is systemic/acute disseminated candidiasis?
A serious yeast infection of blood or other normally sterile sites with Candida species.
Where is systemic candidiasis commonly disseminated?
To the kidney, liver, spleen, retina, bones, CNS, heart, and areas with venous catheters.
What is the management for systemic candidiasis?
Start the patient on an IV echinocandin antifungal (e.g., Anidulafungin) and repeat blood cultures after 48 hours.
What should be done after the first negative blood culture in systemic candidiasis?
The patient should take oral echinocandin antifungal for a minimum of 2 weeks.
What is Pityriasis Versicolour?
A superficial yeast infection of the skin caused by Malassezia furfur, characterized by plaques of discoloured skin.
What percentage of patients present with Pityriasis Versicolour?
96%
What are the characteristics of plaques in Pityriasis Versicolour?
Hypopigmented and hyperpigmented plaques that are well-demarcated, can be confluent, and may be scaly.
What symptoms do patients with Pityriasis Versicolour typically experience?
Patients are usually asymptomatic but can experience pruritus.
How is Pityriasis Versicolour investigated?
Through a skin scrape test or fungal swab.
What is the microbiological appearance of Pityriasis Versicolour?
“Spaghetti and meatball appearance” as the round yeasts produce filaments.
What is the management for Pityriasis Versicolour?
2.5% Selenium sulfide/ketoconazole shampoo or topical antifungals such as clotrimazole or terbinafine.
What is the treatment for resistant cases of Pityriasis Versicolour?
Oral antifungals such as Fluconazole or Itraconazole.
What is Erysipelas?
A bacterial skin infection involving the upper dermis that extends into the superficial cutaneous lymphatics, caused by S. aureus and S. pyogenes.
Characterized by a tender, erythematous patch that is raised and sharply demarcated from surrounding normal skin.
How is Erysipelas treated?
Treated by beta-lactams.
What is Cellulitis?
A bacterial skin infection involving all skin layers, caused by S. aureus and S. pyogenes.
Characterized by a tender, erythematous patch that is poorly demarcated and edematous, resembling orange peel.
How is Cellulitis treated?
Treated by beta-lactams.
