Skin Infections and Infestation Flashcards
What are some examples of skin infections?
- Impetigo
- Folliculotis
- Cellulitis
- Erysipela
- Syphilis
- Leprosy (Hansen’s disease)
- Rickettsial disease (spotted fever and scrub typhus)
What is leprosy also known as?
Hansen’s disease
What is impetigo?
Common and highly contagious skin infection that mainly affects infants and children. Impetigo usually appears as red sores on the face, especially around a child’s nose and mouth, and on hands and feet. The sores burst and develop honey-colored crusts.
What is the most common bacterial infection in children?
Impetigo
What are some predisposising factors to impetigo?
- Warm temperature
- High humidity
- Poor hygiene
- Skin trauma
What bacteria usually causes impetigo?
Caused by staph aureus, to a lesser degree strep pyogenes
What is the treatment for impetigo?
- Local wound care
- Topical antibiotics
What is folliculitis?
Infection of hte hair colliculi
What bacteria most commonly cuses folliculitis?
Staph aureus
What are some predisposing factors to folliculitis?
- Occlusion
- Maceration and hyperhydration
- Shaving or waving
- Topical corticosteroids
- Diabetes
Where on the body does folliculitis normally occur?
Normally occurs on face, chest, back, axillae or buttocks
What investigation is useful with folliculitis?
Bacterial culture cna help identify causative orgnanisms
What is the treatment of folliculitis?
- Antibacterial washes
- Antibacterial ointments
What is erysipelas?
Infection of dermis with lymphatic involvement, most commonly caused by group A streptococci
What bacteria most commonly causes erysipelas?
Group A streptococci
Who usually suffers from erysipelas?
Disease of the very young, elderly, the dehilitated and those with lymphedema or chronic cutaneous ulcers
What is the clinical presentation of erysipelas?
Erythema with well defined margins
Affected skin fells hot, tense and indurated
Affects face and lower extremities
What is required to diagnose erysipelas?
- Clinical
- Lab may show an elevated leukocyte count with a left shift
What is the treatment of erysipelas?
- 10-14 day course of penicillin
What is cellulitis?
Infection of the deep dermis and subcutaneous tissue
What is cellulitis most commonly caused by?
Strep pyogenes and staph aureus
What are risk factors for cellulitis?
- Lymphedema
- Alcoholism
- Diabetes
- IV drug buse
- Peripheral vascular disease
What is the clinical presentation of cellulitis?
- Affected areas show
- Rubor (erythema)
- Calor (warmth)
- Dolor (pain)
- Tremor (swelling)
- Lesion has ill-defined non-palpable borders
Describe the lesion due to cellulitis?
Ill-defined and non-palpabe borders
What is required to diagnose cellulitis?
- Clinical
- Leukocyte count is usually normal and blood cultures are negative in most cases
What is the treatment of cellulitis?
Antibiotics
What is syphilis?
Complex sexually transmitted infection (STI) caused by bacteria Treponema Pallidum
What is syphilis caused by?
Treponema pallidum
What is the clinical presentation of syphilis?
Episodes of active disease followed by latent periods
Widespread rash and flu like symptoms develop next (secondary syphilis)
If left untreated tertiary syphilis may develop years layer and cause a variety of problems:
- Affecting brain, eyes, heart and bones
What can happen if syphilis is left untreated?
If left untreated tertiary syphilis may develop years layer and cause a variety of problems:
- Affecting brain, eyes, heart and bones
What investigations are done for syphilis?
- Serological tests turn positive about 5 to 6 weeks after acquiring infection
- Non-specific non-treponemal tests (VDRL)
- Specific anti-treponemal antibody tests (TTPA)
What does VDRL stand for?
Non-specific non-treponemal tests
What does TTPA stand for?
Specific anti-treponemal antibody tests
What is the treatment of syphilis?
- Penicillin by injection depending on stage of disease
What are the different kinds of syphilis?
Primary syphilis
Secondary syphilis
Tertiary syphilis
What is the clinical presentation of primary syphilis?
Initially syphilis appears as painless sore (ulcer) where infection entered:
- Usually around genitals, anus or mouth
- Sore is known as a chancre
- Single small firm red painless papule quickly ulcerates
When does primary syphilis advance to secondary?
3 weeks to 3 months after 1st stage, widespread rash occurs:
- May be subtle or appear as rough, red or reddish brown papules or patches
- Occurs typically on trunk and often affects palms and soles
- Does not itch
What is the clinical presentation of secondary syphilis?
- May be subtle or appear as rough, red or reddish brown papules or patches
- Occurs typically on trunk and often affects palms and soles
- Does not itch
In what phase of syphilis is the patient infectious and can transmit to their partner?
Tertiary syphilis
What is the clinical presentation of tertiary syphilis?
Normally no signs on clinical examination:
- Solitary granulomatous lesions (gummas) may be found on skin, in mouth and throat or occur in bones
- Brain, spinal cord, heart, liver, eyes may also be affected
What are some examples of viral skin infections?
- Herpes simplex
- Chicken pox
- Shingles
- Viral warts
- Molluscum contagiosum
What does HVS stand for?
Herpes simplex virus
What are the different kinds of HSV?
HVS 1
HVS 2
What is herpes?
Orobalial and genital infection
What is the clinical presentation of HSV1?
- Presents usually between 20-40 years old
- Often asymptomatic in children <10 years
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What is HSV2?
What is the clinical presentation of HSV2?
Sore areas with erythematous base, with vesicles followed by pustules and ulcerations
What is the treatment of herpes?
Antiviral therapy depends on type (topical or systemic)
What is the aetiology of chickenpox and herpes zoster (shingles)?
VZV
What is the medical term for shingles?
Herpes zoster
What does herpes zoster represent?
Herpes zoster represents reactivation of latent varicella
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What is the clinical presentation of chickenpox?
Is a highly contagious viral infection that causes acute fever and blistered rash, mainly in children
Easily spread from person to person by breathing in airborne respiratory droplets from an infected persons coughing or sneezing or through direct contact with the fluid from the open sores
Red macules, vesicules, pustules, crusts
How does chickenpox spread from person to person?
Easily spread from person to person by breathing in airborne respiratory droplets from an infected persons coughing or sneezing or through direct contact with the fluid from the open sores
What is the treatment of chickenpox?
- Symptomatics
- Calamine lotion
What does VZV stand for?
Varicella-zoster virus (VZV)
What is the clinical presentation of shingles?
Localised, blistering and painful rash caused by reactivation of varicella-zoster virus (VZV)
Characterised by dermatomal distribution
Blisters are confined to the VZV remains dormant in dorsal root ganglia nerve cells in the spine
What are some complications of shingles?
Infection
Post-herpetic neuralgia
What is neuralgia?
stabbing, burning, and often severe pain due to an irritated or damaged nerve
What is the treatment of shingles?
- Keep are clean to prevent infection
- Pain relief
- Rest
What are viral warts caused by?
Human pipillomavirus
What is the presentation of viral warts?
- Pain
- Discomfort
Hyperkeratonic papules, thick hyperkeratotic plaques (when grouped in clusters they are referred to as mosaic)
Most warts resolve spontaneously
What are the leions like in viral warts?
Hyperkeratonic papules, thick hyperkeratotic plaques (when grouped in clusters they are referred to as mosaic)
In what age group is viral warts most common?
Children
What is the treatment of viral warts?
- Salicylic acid
- Cryotherapy
When should patients with viral warts be referred to secondary therapy?
Referral to secondary care should happen when diagnostic uncertainty exists, patient is immunocompromised or warts are large or extensive
What is molluscum contagiosum?
Common viral infection that mainly affects infants and young children
Who does molluscum contagiosum mainly affect?
Infants and young children
Where is molluscum contagiosum more prevalent?
Warm climates and overcrowded environments
What is molluscum contagiosum caused by?
Poxvirus (poxviradae family)
Describe the lesions due to molluscum contagiosum?
Lesions are firm, umbilicated perly papules with waxy surface, most common in skinfolds and genital region
What is the treatment of molluscum contagiosum?
- Curettage
- Liquid nitrogen
- Chemovesicants
What are some examples of fungal skin infections?
- Dermatophytosis
- Ability to invade and multiply within keratinised tissue (hair, nail and skin)
- Candidiasis
- Opportunistic pathogenic fungi
- Common member of human gut flora
- Pityriasis versicolor
- Normal flora of human skin
- Cause non-inflammatory superficial mycosis
What is pityriasis versicolor normal flora of?
Human skin
What does pityriasis versicolor cause?
Non-inflammatory superficial mycosis
What is mycosis?
Fungal infections of animals
What is cadidiasis normal flora of?
Gut flora
What is dermatophytosis?
An infection of the hair, skin, or nails caused by a dermatophyte, which is most commonly of the Trichophyton genus and less commonly of the Microsporum or Epidermophyton genera.
What are different kinds of dermatophytosis?
- Tinea corporis
- Ringworm
- Tinea cruris
- Ringworm of the groin
- Tinea capitis
- Ringworm of the scalp
- Tinea pedis
- Ringworm of the foot
- Tinea ungium
- Ringworm of the nail
What is tinea corporis?
Ringworm
What is tinea cruris?
Ringworm of the groin
What is tinea capitis?
Ringworm of the scalp
What is tinea pedis?
Ringworm of the foot
What is tinea umgium?
Ringworm of the nail
What are some predisposising factors to mucocutaneous candida infections?
- Diabetes
- Occlusion
- Hyperidrosis
- Broad spectrum antibiotics
- Immunosuppresion
What are mucocutaneous candida infections caused by?
Candida albicans
What is the presentation of mucocutaneous candida infections?
- On the skin, erythematous patches often accompanied by satellites pastules
- Intertriginous zones and diaper areas in infants
What is the treatment of mucocutaneous candida infections?
- Remove predisposing factors
- Topical antifungals
- Oral antifungals in some cases
What is pityriasis versicolour?
Common fungal infection that causes small patches of skin to become scaly and discoloured
Where is pityriasis verticolour often found on the body?
Sebum rich areas of the skin
What is pityriasis versicolour caused by?
Malassezia species
What is the predisposition to pityriasis versicolour?
- High temperatures and humidity
- Oil skin
- Excessive sweating
What are the lesions due to pityriasis versicolour like?
Multiple oval to round patches with mild scale
What is the treatment of pityriasis versicolour?
Topical antimycotic (shampoos, creams)
What are examples of infestations?
- Scabies
- Lice
What is scabies?
Host-specific itch mite sarcoptes scabiei
What is scabbies caused by?
Sarcoptes scabiei
How is scabbies transmitted?
Via direct close contact
What are some predisposing factors to scabbies?
- Overcrowding
- Delayed treatment
What is required for the diagnosis of scabbies?
- Skin scraping
- Burrows visualisation
What is the clinical presentation of scabbies?
Itch is characteristically more severe at night, causing disturbed sleep:
- Affects trunk and limbs, sparing the scalp
Scabies burrows appear as 0.5-1.5cm grey irregular tracks in the web spaces between fingers, palms and wrists
Describe scabbies burrows?
Scabies burrows appear as 0.5-1.5cm grey irregular tracks in the web spaces between fingers, palms and wrists
What is the treatment of scabbies?
- Antiscabietic topical treatment
- Oral medicine might be needed in some cases
What is head lice?
Itch and irritation in the scalp
Lice favour the nape of the neck and the skin behind ears
Where do lice prefer to live?
Lice favour the nape of the neck and the skin behind ears
What are nits?
Nits are the empty egg cases attached to hair that head lice hatch from
What are nits observed as?
Adherent white grains on the hair shaft
What is the treatment of head lice?
- At least 2 applications of an insecticide and/or physical methods
- Treat all members of the family at the same time
- Inform the day care or school
What is observed with head lice?
Nits are easier to see after the eggs have hatched, as adherent white grains on the hair shaft
Red-brown spots on skin are due to excreted digested blood