Derm - Infections + Infestations Flashcards
What is staphylococcus aureus and how does it infect the skin?
bacterium that has many virulence factors, e.g. receptord that allow it to bind to fibrin
fibrin is in abundance on wound surfaces etc.
What can Staph infections result in?
→ ecthyma (deep dermis skin infetion where ulcers form under crusted sores)
→ impetigo (superficial skin infection)
→ cellulitis
→ folliculitis
→ furunculosis (deep infection of the hair follicle leading to abscess formation)
→ carbuncles (cluster of boils — painful, pus-filled bumps)
→ SSSS (staphylococcal scalded skin syndrome)
→ superinfects other dermatoses (e.g. atopic eczema, HSV, leg ulcers)
How does streptococcus cause skin infections?
→ virulence factors that allow it to attach to the epithelial surfaces via the lipoteichoic acid portion of fimbriae
→ has M protein (anti-phagocytic) + hyaluronic acid capsule
→ produces erythrogenic exotoxins
→ produces streptolysins S and O
What can a Stretococcus infection result in?
→ ecthyma
→ cellulitis
→ impetigo
→ erysipelas (an infection of the upper layers of the skin +
→ scarlet fever
→ necrotizing fascitis
→ superinfects other dermatsoses (e.g. leg ulcers)
What is folliculitis?
→ folliculitis
→ follicular erythema, sometimes pustular
→ maybe non-infectious or infectious
What kind of folliculitis is associated with HIV?
eosinophillic (non-infectious) folliculitis
What can give you recurrent folliculitis?
nasal carriage of staphylococcus aureus, especially strains expressing Panton-Valentine leukocidin (PVL)
How is folliculitis treated?
→ antibiotics (usually flucloxacillin or erythromycin) (depends after a swab)
→ incision + drainage is required for furunculosis
What is the difference between a furuncle + carbuncle?
→ furuncle = deep follicular abscess
→ carbuncle = deep follicular abcess that involves adjacent connected follicles
→ carbuncle more likely to lead to complications such as cellulitis + septicaemia
What is this?
furuncle
What is this?
carbuncle
Why do some patients develop recurrent staphylococcal impetigo or recurrent furunculosis?
• Establishment as a part of the resident microbial flora :
- Abundant in nasal flora
•Immune deficiency :
- Hypogammaglobulinaemia
- HyperIgE syndrome – deficiency - Chronic granulomatous disease
- AIDS
- Diabetes Mellitus
What is PVL?
→ Panton-Valentine Leukocidin
→ β-pore-forming exotoxin
What does PVL allow staphylococcus aureus to do?
→ Leukocyte destruction and tissue necrosis
→ Higher morbidity, mortality and transmissibility
How does PVL staph. aureus manifest in the skin?
→ recurrent + painful abcesses
→ folliculitis
→ cellulitis
→ often in more than one site, recurrent + present in contacts
How does PVL staph. aureus manifest extracutaneously?
→ necrotising pneumonia
→ necrotising fascitis
→ purpura fulminans
What are the 5 risks or ways in which PVL staph. aureus can be acquired?
Close contact (hugging, contact sports)
Contaminted items (gym equipment, towels, razors)
Crowding (crowded living conditions)
Cleanliness of environement (unclean = more risk)
Cuts + grazes (allows bacteria to enter the body)
What is the treatement protocol for PVL staph. aureus infection?
→ consult local microbiologist
→ antibiotics (usually tetracycline)
→ decolonisation (e.g. chlorhexidine body wash for 7 days or nasal application of mupirocin ointment, 5 days)
→ treatment of close contacts
What is pseudomonal folliculitis?
an infection of the hair follicle with Pseudomonas bacteria
What causes pseudomonal folliculitis?
associated with hot tub use, swimming pools, depilatories + wet suits
How does pseudomonal folliculitis progress?
appears 1-3 days after exposure, as a diffuse truncal eruption or follicular erythmatous papule
rarely can progress to abcesses, lymphangitis + fever
How is pseudomonal folliculitis treated?
most cases self-limited, no treatement required
severe or recurrent cases can be treated with oral ciprofloxacin
What is this?
cellulitis - infections of lower dermis + subcutaneous tissue
What is the main symptom of cellulitis?
tender swelling with ill-defined blanching erythema or oedema
What causes cellulitis?
→ streptococcus pyogenes
→ staphylococcus aureus
What is a pre-disposing factor for cellulitis?
oedema
What is the treatment for cellulitis?
systemic antibiotics
What is this?
impetigo
What is impetigo?
Superficial bacterial infection, stuck-on, honey-coloured crusts overlying an erosion, often affects face (perioral, ears, nasal)
What can cause impetigo?
streptococci (non-bullous or non-blistering)
staphylococci (bullous or blistering)
How do you tell the difference between staph + strep impetigo?
strep = non-blistering or non-bullous
staph = bullous or blistering
Why does staph cause blistering or bullous in impetigo?
Caused by exfoliative toxins A & B, split epidermis by targeting desmoglein I
How is impetigo treated?
topical +/- systemic antibiotics
What is impetiginastion?
superficial impetigo in the context of atopic dermatitis
caused by staph
characteristic gold crust
What is this?
impetiginisation
What is ecthyma?
severe form of streptococcal impetigo
thich crust overlying a punch out ulceration surrounded by erythema
usually on lower extremities
What is SSSS?
staphylococcal scalded skin syndrome
Who usually gets SSSS?
neonates, infants, immunocompromised adults
What causes SSSS?
the exfoliative toxins of staph
Why can’t the staph organism be cultured from the scalded skin in SSSS?
infection occurs at a distant site from the SSSS
Why does SSSS often manifest in neonates, infants or immunocompromised adults?
→ kidneys cannot excrete the exfoliative toxin quickly
→ Diffuse tender erythema that rapidly progresses to flaccid bullae
→ Wrinkle and exfoliate, leaving oozing erythematous base
What can SSSS clinically resemble?
Stevens-Johnson syndrome / toxic epidermal necrolysis
What is Toxic Shock Syndrome?
febrile illness due to group A staph. aureus strain that produces pyrogenic exotoxin TSST-1
What are the symptoms + signs of Toxic Shock Syndrome?
- fever > 38.9
- Hypotension
- Diffuse erythema
- Involvement of ≥ systems:
– Gastrointestinal
– Muscular
– CNS
- Renal
- Hepatic
- Mucous membranes (erythema)
- Hematologic (platelets <100 000/mm3)
- Desquamation predominantly of palms and soles 1-2 weeks after resolution of erythema
What is this?
toxic shock syndrome
What is erythrasma?
infection of Corynebacterium minutissimum
What are the symptoms + signs of erythrasma?
well demarcated patches in intertriginous areas
intially pink
become brown + scaly
What is this?
erythrasma
What is pitted keratolysis?
pitted erosions of soles
What is pitted keratolysis caused by?
corynebacteria
What is the treatment for pitted keratolysis?
topical clindamycin
What is erysipeloid?
erythema + oedema of the hand after handling contaminated raw fish or meat
extends slowly over weeks
What bacteria causes erysipeloid?
erysipelothrix rhusiopathiae
What is this?
erysipeloid
What is anthrax?
Painless necrotic ulcer with surrounding oedema and regional lymphadenopathy (with pain in lymph nodes) at the site of contact with hides, bone meal or wool infected with Bacillus anthracis
What causes anthrax?
Bacillus anthracis
What is this?
anthrax
What is blistering distal dactylitis?
Rare infection
Typically - young children
1 or more tender superficial bullae on erythematous base on the volar fat pad of a finger
Toes may rarely be affected
What can cause blistering distal dactylitis?
streptococcus pyogenes and staphylococcus aureus
What is this?
blisteirng distal dactylitis
What is erysipelas?
infection of deep demris + subcutis
What causes erysipelas?
β-haemolytic streptococci or Staphylococcus aureus
What are the symptoms + signs of erysipelas?
Painful
Prodrome of malaise, fever, headache.
Presents as erythematous indurated plaque with a sharply demarcated border and a cliff-drop edge (+/- blistering)
Face or limb (+/- red streak of lymphangitis and local lymphadenopathy)
Portal of entry must be sought (e.g. tinea pedis).
Systemic symptoms (fever, malaise).
What is the treatment for erysipelas?
Treated with intravenous antibiotics
What is scarlet fever?
bacterial illness that develops in some people who have strep throat
primarily a disease of children
What is scarlet fever caused by?
Caused by upper respiratory tract infection with erythrogenic toxin-producing Streptococcus pyogenes
What are the symptoms + progression of scarlet fever?
- Preceded by sore throat, headache, malaise, chills, anorexia and fever
- Eruption begins 12-48 hours later
- Blanchable tiny pinkish-red spots on chest, neck and axillae
- Spread to whole body within 12 hours
- Sandpaper-like texture
What are some complications of scarlet fever?
otitis, mastoiditis, sinusitis, pneumonia, myocarditis, hepatitis, meningitis, rheumatic fever, acute glomerulonephritis
What is this?
scarlet fever
What is necrotising fasciitis?
Initial dusky induration (usually of a limb), followed by rapid painful necrosis of skin, connective tissue and muscle
What causes necrotising fasciitis?
streptococci
staphylococci
enterobacteria
anaerobes
What is the mortality of necrotising faciitis?
potentially fatal
high mortality
What is the diagnostic procedure for necrotising fasciitis?
- Prompt diagnosis essential (requires high index of suspicion)
- MRI can aid diagnosis.
- Blood and tissue cultures can determine organisms and sensitivities.
How is necrotising fasciitis treated?
broad-spectrum parenteral antibiotics and surgical debridement
What is atypical mycobacterial infection?
important cause of infection in immunosupressed states
What can cause atypical mycobacterial infection?
mycobacterium marinum
mycobacterium chelonae
mycobacterium ulcerans
What type of infection does mycobacterium marinum cause?
indolent granulomatous ulcers (fish-tank granuloma) in healthy people (Sporotrichoid spread)
What type of infection does mycobacterium chelonae + abscessus cause?
puncture wounds, tattoos, skin trauma or surgery
What type of infection does mycobacterium ulcerans cause?
an important cause of limb ulceration in Africa (Buruli ulcer) or Australia (Searle’s ulcer)
What is this? What caused this?
atypical mycobacterial infection, mycobacterium marinum
What is this? What caused this?
atypical mycobacterium infection, mycobacterium abscessus + chelonae
What is borreliosis (Lyme Disease)?
annular erythema developing at the site of the bite of a Borrelia-infected tick, Bite form Ixodes tick infected with Borrelia burgdorferi
What is the cutaneous manifestation of Borreliosis?
Erythema migrans (only in 75%)
Erythematous papule at the bite site
Progression to annular erythema of >20cm
What is the symptomatic progression of Borreliosis (Lyme Disease)?
- 1-30 days after infection, fever, headache
- Multiple secondary lesions develop - similar but smaller to initial lesion
- Neuroborreliosis
- Facial palsy / other CN palsies
- Aseptic meningitis
- Polyradiculitis
- Arthritis – painful and swollen large joints (knee is the most affected join)
- Carditis
What is this?
Borreliosis (Lyme Disease)
What is this?
Borreliosis (Lyme Disease)
What is Tularaemia?
zoonotic bacterial disease of the Northern hemisphere
What causes Tularaemia?
Francisella tularensis
How is tularaemia acquired?
- Handling infected animals (squirrels and rabbits)
- Tick bites
- Deerfly bites
What is the cutaneous manifestation of tularaemia?
Ulceroglandular form
Primary skin lesion is small papules at inoculation site that rapidly necroses – leading to painful ulceration
+/- local cellulitis
What are the other systemic symptoms of tularaemia?
- Painful regional lymphadenopathy
- Systemic symptoms: fever, chills, headache and malaise
What is this?
Tularaemia
What is ecthyma gangrenosum? What does it look like clinically?
infection that manifests cutaneously
- Red macule(s) → oedematous → haemorrhagicbullae.
- May ulcerate in late stages or form an eschar surrounded by erythema
What causes ecthyma gangrenosum?
Pseudomonas aeruginosa
Who normally catches ecthyma gangrenosum?
neutropaenic patients, critically ill + imunocompromised patients
What is an escharotic lesion?
substance that kills unwanted or diseased tissue, usually skin or superficial growths like warts, leaving them to slough off
What can cause an escharotic lesion?
- Pseudomonas
- Aspergillosis
- Leishmaniasis
- Cryptococcosis
- Lues maligna
- Rickettsial infections
- Cutaneous anthrax
- Tularaemia
- Necrotic arachnidism (brown recluse spider bite)
- Scrub typhus (Orientia tsutsugamushi)
- Rat bite fever (Spirillum minus)
- Staphylococcal or streptococcal
- Ecthyma
- Lyme disease.
What is syphilis?
bacterial infection usually spread by sexual contact. The disease starts as a painless sore — typically on the genitals, rectum or mouth
What causes syphilis? How is it spread?
treponema pallidum, sexually transmitted disease
What does the primary infection of syphilis look like?
● Primary infection Chancre -painless ulcer with a firm indurated border
● Painless regional lymphadenopathy one week after the primary chancre
● Chancre appears within 10-90 days
What is secondary syphilis?
the second stage of syhpilis, Begins ~50 days after chancre
What are the symptoms of secondary syphilis?
- Malaise, fever, headache, pruritus, loss of appetite, iritis
- Rash (88-100%) -Pityriasis rosea-like rash
- Alopecia (‘moth-eaten’) (hair loss patches, etc.)
- Mucous patches
- Lymphadenopathy
- Residual primary chancre
- Condylomata lata (flesh colored or hypopigmented, macerated papules or plaques)
- Hepatosplenomegaly
Why is there a low threshold for testing for secondary syphilis?
symptoms are extensive and very variable, presentations can vary form person to person, like in sarcoidoisis, called the “great mimicker”
What is a rare cutaneous manifestation of secondary syphilis?
Lues maligna
● Pleomorphic skin lesions with pustules, nodules and ulcers with necrotising vasculitis
● More frequent in HIV manifestation
What is tertiary syphyilis? What are its symptoms?
● Gumma Skin lesions - nodules and plaques
● Extend peripherally while central areas heal with scarring and atrophy
● Mucosal lesions extend to and destroy the nasal cartilage
● Cardiovascular disease
● Neurosyphilis (general paresis or tabes dorsalis)
What is the treatement for syphilis?
IM benzylpenicillin or oral tetracycline
What is leprosy? What causes leprosy?
Hansen’s disease, is a chronic infectious disease caused by Mycobacterium leprae (obligate intracellular bacterium)
mainly affects the skin, the peripheral nerves, mucosal surfaces of the upper respiratory tract and the eyes
What are the 2 different types of leprosy?
lepromatous leprosy
tuberculoid leprosy
What are the features of lepromatous leprosy?
- Multiple lesions: macules, papules, nodules
- Sensation and sweating normal (early on)
What are the features of tuberculoid leprosy?
- Solitary or few: elevated borders – atrophic center, sometimes annular
- Hairless, anhidrotic, numb
What are the 3 ways in which TB can be acquired cutaneously?
- exogenously
- contiguous endogenous spread
- haematogenous / lymphatic endogenous spread
How does TB present exogenously?
primary-inoculation TB and tuberculosis verrucosa cutis (see picture)
How does TB present contiguous endogenously?
scrofuloderma or autoinoculation – periorificial tuberculosis
(skin condition caused by tuberculous involvement of the skin by direct extension)
How does TB present when spread throug haematogenous / lymphatic endogenous spread?
dissemination (lupus vulgaris, miliary tuberculosis, gummas)
What investigations can be done for TB when there is cutaneous presentation?
- Interferon-γ release assay (Quantiferon-TB)
- Histology – ZN stain
- Culture / PCR
What are the different ways in which TB can manifest cutaneously?
- Tuberculous chancre - painless, firm, reddish-brown papulonodule that forms an ulcer
- Tuberculosis verrucosa cutis - wart-like papule that evolves to form redbrown plaque
- Scrofuloderma – subcutaneous nodule with necrotic material - becomes fluctuant and drains, with ulceration and sinus tract formation.
- Orificial TB - non-healing ulcer of the nasal mucosa that is painful
- Lupus vulgaris – red brown plaque - +/- central scarring, ulceration
- Miliary TB - pinhead-sized, bluish-red papules capped by minute vesicles
- Tuberculous gumma – firm subcutaneous nodule - later ulcerates
What is molluscum contagiosum?
● Poxvirus infection
● Usually resolve spontaneously
Who is molluscum contagiosum common in?
common in chlidren + immunocompromised
What are some diffrenetial diagnosis for molluscum contagiosum?
- Verrucae
- Condyloma acuminata
- Basal cell carcinoma
- Pyogenic granuloma
What are the treatment options for mulluscum contagiosum?
● Usually resolve spontaneously
● Treatment options – curettage, imiquimod, cidofovir
What areas of the body does the Herpes Simplex Virus cutaneously favour?
orolabial and genital regions w primary and recurrent vesicular eruptions
How is HSV transmitted?
● HSV-1 – direct contact with contaminated saliva / other infected secretions
● HSV-2 - sexual contact
but not a hard + fast rule
Transmission can occur even during asymptomatic periods of viral shedding
How does HSV infect someone?
● Replicates at mucocutaneous site of infection
● Travels by retrograde axonal flow to dorsal root ganglia
When do symptoms present? What are the primary symptoms?
●Symptoms with 3-7 days of exposure
●Preceded by tender lymphadenopathy, malaise, anorexia
± Burning, tingling
●Painful rouped vesicles on erythematous base → ulceration / pustules / erosions with scalloped border
●Crusting and resolution within 2-6 weeks
●Orolabial lesions – often asymptomatic
●Genital involvement – often excruciatingly painful→ urinary retention
What are some of the systemic manifestations of HSV?
aseptic meningitis in up to 10% of patients
How are HSV flare-ups reactivated?
spontaneous, UV, fever, local tissue damage, stress
What is eczema herpeticum?
- HSV triggered eczema for people who already have eczema
- emergency
- Monomorphic, punched out erosions (excoriated vesicles)
What is herpetic whitlow?
- HSV (1>2) infection of digits – pain, swelling and vesicles (vesicles may appear later)
- Misdiagnosed as paronychia or dactylitis
- Often in children
What is herpes gladiatorum?
- HSV 1 involvement of cutaneous site reflecting sites of contact with another athlete’s lesions
- Contact sports e.g. wrestling
How is neonatal HSV acquired? What are the symptoms?
- Exposure to HSV during vaginal delivery – risk higher when HSV acquired near time of delivery
- HSV 1 or 2
- Onset from birth to 2 weeks
- Localised usually – scalp or trunk
- Vesicles → bullae erosions
- Encephalitis → mortality >50% without treatment, 15% with treatment → neurological deficits
What is the treatment for neonatal HSV infection?
requires antivirals
How does severe or chronic HSV infection present?
- Immunocompromised patients e.g. HIV / transplant recipient
- Most common presentation – chronic, enlarging ulceration
- Multiple sites or disseminated
- Often atypical e.g. verrucous, exophytic or pustular lesions
- Involvement of respiratory or GI tracts may occur
How is HSV diagnosed?
swab for PCR testing
What is the treatement for HSV?
- Don’t delay
- Oral valacyclovir or acyclovir 200mg five times daily in immunocompetent localised infection
- Intravenous 10mg/kg TDS X 7-19 days
What is varicella zoster virus? What does it cause?
the cause of chickenpox and herpes zoster (also called shingles)
can be single dermatomal or multidermatomal
What is hand foot + mouth disease? What causes it?
common infection that causes mouth ulcers and red spots on the hands and feet. It mainly affects children
caused by Coxsackie A16, Echo 71
An acute self-limiting coxsackievirus infection
How is hand, foot + mouth disease transmitted?
•Spread by direct contact via oral-oral route or oral faecalroute.
What are the symptoms of hand, foot + mouth disease?
- Prodrome of fever, malaise, and sore throat
- Red macules, vesicles (typically gray and eliiptical), and ulcers develop on buccal mucosa, tongue, palate and pharynx, and may also develop on hands and feet (acral and volar surfaces).
What is hand foot and mouth disease caused by echo 71 associated with?
higher incidence of neurological involvement included fatal cases of encephalitis
What viruses can cause morbilliform (measle-like) rashes?
- Measles, Rubella, EBV, CMV, HHV6 & HHV7 cause morbilliform (measles-like) eruptions
- Leptospirosis
- Rickettsia
What can cause petechial / purpuric eruptions?
- Coagulation abnormalities - TTP, ITP, DIC
- Vasculitis
- Infections
- Viruses - Hepatitis B, CMV, Rubella, Yellow fever, Dengue fever, West nile virus
- Bacterial (BREN) - Borrelia, Rickettsia, Neisseria, Endocarditis
- Other infections - Plasmodium falciparum, Trichinella
- Other - TEN, Ergot poisoning, Raynauds
What is Gianotti-Crosti syndrome?
- papular acrodermatitis of childhood
- A viral eruption that causes and acute symmetrical erythematous papular eruption on face, extremities and buttocks – usually in children aged 1-3 years
What can cause Gianotti-Crosti syndrome?
- EBV (most common)
- CMV
- HHV6
- Coxsackie viruses A16, B4 and B5
- Hepatitis B
What is erythema infectiousum caused by?
parvovirus B19
What are the symptoms of erythema infectiosum?
- Initially: mild fever and headache
- A few days later – ‘slapped cheeks’ for 2-4 days
- Then reticulated (lacy) rash of chest and thighs in 2nd stage of disease
What is roseola infantum? What are the symptoms?
- viral infection that affects children
- 2-5 days of high fever
- Followed by appearance of small pale pink papules on the trunk and head
- Lasts hours to 2 days.
What cuases roseala infantum?
HHV6 and HHV7 commonly
What is Orf? What are the symptoms?
Viral infection
- Dome-shaped, firm bullae that develop an umbilicated crust.
- Usually develop on hands and forearms
- They generally resolve without therapy in 4-6 weeks
What causes Orf?
- Caused by parapoxvirus
- Direct exposure to sheep or goats
What causes warts?
over 200 types of HPV (human papilloma virus)
What can warts be mistaken for?
skin cancer
condolymata lata
What fungi cause superficial skin infections?
- candida
- malassezia
- dermatophytes
What is pityriasis versicolor? What causes it? What are the symptoms?
superficial fungal infection
- Hypopigmented, hyperpigmented or erythematous macular eruption +/- fine scale
- Malassezia spp.
- Begins during adolescence (when sebaceous glands become active)
- Flares when temperatures and humidity are high – Immunosuppression
- Topical azole
What are dermatophytes?
fungi that live on keratin
What strain causes the most fungal infections?
trichophyton rubrum
What causes the most tinea capitis (Ringworm of the scalp)?
trichophyton tonsurans
What is a kerion?
an inflammatory fungal infection that may mimic a bacterial folliculitis or an abscess of the scalp; scalp is tender and patient usually has posterior cervical lymphadenopathy
- Frequently secondarily infected with Staphylococcus aureus
What is onychomycosis?
fungal infection of the nails that causes discoloration, thickening, and separation from the nail bed
What is tinea faciei?
superficial dermatophyte infection limited to the glabrous skin of the face
What is tinea pedis?
Athlete’s foot (tinea pedis) is a fungal skin infection that usually begins between the toes
What kind of tinea pedis does trichophyton rubrum cause?
scaling + hyperkeratosis of plantar surface of foot
What kind of tinea pedis does tricophyton mentagrophytes (interdigitale) cause?
sometimes vesiculobullous reaction on arch or side of foot
What are Id reactions?
- Dermatophytid reactions
- Inflammatory reactions at sites distant from the associated dermatophyte infection
- May include urticaria, hand dermatitis, or erythema nodosum
- Likely secondary to a strong host immunologic response against fungal antigens
What is majocchi granuloma?
•Follicular abscess produced when dermatophyte infection penetrates the follicular wall into surrounding dermis; tender
What can cause majocchi granuloma?
trichophyton rubrum or mentagrophytes
What is candidiasis? What are the causes + symptoms?
- Candida albicans
- Predisposed by occlusion, moisture, warm temperature, diabetes mellitus
- Most sites show erythema oedema, thin purulent discharge
- Usually an intertriginous infection (affecting the axillae, submammaryfolds, crurae and digital clefts) or of oral mucosa.
- A common cause of vulvovaginitis
- May affect mucosae.
- Can become systemic (immunocompromise)
What are deep fungal infections?
- Capacity for deep invasion of skin or production of skin lesions secondary to systemic visceral infection.
- Subcutaneous fungal infections – infections of implantation (inoculation)
What are some examples of deep fungal infections?
- Sporotrichosis
- Phaeohypomycosis
- Chromomycosis
- Mycetoma (Madura foot)
- Lobomycosis
- Rhinosporidiosis
What is sporotrichosis?
known as “rose gardener’s disease”) is an infection caused by a fungus called Sporothrix. This fungus lives throughout the world in soil and on plant matter such as sphagnum moss, rose bushes, and hay. People get sporotrichosis by coming in contact with the fungal spores in the environment
What is chromomycosis?
chronic fungal infection of the skin and subcutaneous tissue caused by any of several pigmented fungi normally found in soil and wood
What is Madura foot (mycetoma)?
chronic granulomatous soft-tissue infection that is endemic to several regions of Africa and Asia
What are systemic fungal infections?
- Systemic respiratory endemic fungal infections Include blastomycosis, histoplasmosis, coccidiodomycosis, paracoccidoiodomycosis, penicillinosis
- Disease in both immunocompetent and immunosuppressed
What is blastomycosis?
rare fungal infection usually acquired by breathing in the spores of the fungi Blastomyces dermatitidis or Blastomyces gilchristii
What is coccidioidomycosis?
Valley fever, also called coccidioidomycosis, is an infection caused by the fungus Coccidioides. The fungus is known to live in the soil in the southwestern United States and parts of Mexico and Central and South America. The fungus was also recently found in south-central Washington.
What is histoplasmosis?
an infection caused by a fungus called Histoplasma. The fungus lives in the environment, particularly in soil that contains large amounts of bird or bat droppings
What is aspergillosis?
- Primarily a respiratory pathogen
- Cutaneous lesions being as well-circumscribed papule with necrotic base and surrounding erythematous halo,
- Propensity to invade blood vessels causing thrombosis and infarction
- Lesions destructive – may extend into cartilage, bone and fascial planes
- Should be considered in differential of necrotisiing lesions
What are the risk factors for aspergillosis?
neutropenia + corticosteroid therapy
What can cause similar illness and cutaneous presentation to aspergillosis?
fusarium
What is mucurmycosis? What are the presenting symptoms?
fever, headache, facial oedema, proptosis, facial pain, orbital cellulitis ± cranial nerve dysfunction
What can cause mucormycosis?
Apophysomyces, Mucor, Rhizopus, Absidia, Rhizomucor
What is mucormycosis associated with?
Diabetes mellitus (1/3 of patients - DKA very high risk
Malnutrition
Uraemia
Neutropaenia
Medications: Steroids / antibiotics / desferoxamine
Burns
HIV
What is the treatment for mucormycosis?
aggressive debridement & antifungal therapy
What is scabies? What are the signs + symptoms?
- Contagious infestation caused by Sarcoptes species
- Female mates, burrows into upper epidermis, lays her eggs and dies after one month.
- Insidious onset of red to flesh-coloured pruritic papules
- Affects interdigital areas of digits, volar wrists, axillary areas, genitalia
- A diagnostic burrow consisting of fine white scale is often seen
- Crusted or ‘Norwegian’ scabies - hyperkeratosis
- Often asymptomatic; found in immunocompromised individuals
What is the treatment for scabies?
permethrin, oral ivermectin
- Two cycles of treatment are required
What are the 3 types of lice?
Pediculus humanus capitis
Pediculus humanus corporis
Phithrus pubis
What are the pediculus humanus capitis?
- Entire live cycle spent in hair
- 2ndary infection common
What is the treatment for head lice?
malathion, permethrin, or oral ivermectin
What is the pediculus humanus corporis?
- Lives and reproduces in clothing – leaves to feed; rarely found on skin
- Pruritic papules & hyperpigmentation
- Found in overcrowding, poverty & poor hygiene
How are body louse treated?
eliminated by thorough cleaning or discarding clothes
What are phithrus pubis?
aka crabs; three pairs of legs
- Eggs found on hair shaft, also found in occipital scalp, body hair, eyebrow and eyelash, axillary hair
- Treatment: malathion / permethrin, oral ivermectin
What are bedbugs?
•Cimex lectularius – reddish-brown, wingless insect resembling size and shape of ladybird
- Itchy weals around a central punctum
- Dine alone at night, rapidly and painlessly
- Live behind wallpaper, under furniture
How are bedbugs gotten rid of?
- Fumigation of home is necessary to get rid of pest
- Treatment of patient is symptomatic
