Infections and Infestations
Dr Iain Henderson
GP Scotstoun
Hospital Practitioner, Western Infirmary
Basic Dermatology Day
Infections
• Bacterial
– Staphylococci
– Streptococci
– Other bacteria
• Viral
– Herpes
– Warts
– Pox viruses
– Others
• Fungal
– Tinea
– Candida
– Pityriasis Versicolor
Skin Functions
•
•
•
•
•
•
Mechanical barrier
Regulates body temp
Sensory
Immunological
Regenerates itself
Protects against trauma,
chemicals, viruses,
bacteria and UV damage
Skin Infections
Bacterial
Staphylococci
•
•
•
•
Folliculitis (hair follicle infections)
Impetigo (school sores)
Boils (Carbuncles and Furunculosis)
Cellulitis (but more often due to
streptococcus)
• Secondary infection in eczema
• Ecthyma (crusted ulcers)
• Scalded skin syndrome
Folliculitis
Need swabs, Usually
Staph if infective. Can
have nasal carriage.
Can be due to trauma –
epilation, occupational
due to tar or oils or
application of greasy
ointments to skin.
Pseudomonas from
jacuzzis and whirlpools.
Impetigo
•
•
•
•
•
Common infection
Can be due to staph or strep
Usually staph in this country
Face usual site
Develops small vesicles that rupture and
then develop a yellow crust
• Can spread easily to others
• Bullous Impetigo is usually due to staph
Boils (furuncles)
• An abscess centred on one or more hair
follicles
• Usually due to Staph
• Commonest sites face, neck, axillae,
buttocks arms and legs
• When developed points and pus is
discharged
• Carbuncle is multiple abscesses coming
together – less common – occurs on neck
in men over 40
Secondary Infection
• Staph and Strep are the most likely
organisms
• Eczema doesn’t have to look that bad to
be infected
• Swabs very useful
• Can see if Fucidic Acid resistance
• Eczema sufferers have a higher rate of
carriage of staph
Ecthyma
• Infection of the full thickness of the
epidermis and dermis by Staph aureus or
sometimes Beta Haemolytic Strep
• Presents as round painful punched out
ulcer with thick crust on top
• Usually children. Commoner in hot humid
climates
• Needs oral Rx as deep and will heal with
scarring.
Staphylococcal Scalded Skin
Syndrome
• Toxin induced
• Staph infection may not be obvious
• Severity varies from localised blisters to
complete skin involvement with de-roofed
bullae
• Raw red moist skin
• Niklolsky’s sign is positive
• Needs antibiotics, analgesic, fluids and
temperature regulation. Nursed as for burns
Staph Scalded Skin Syndrome
• Usually affects small children esp
neonates Red blistered skin like burns or
scalds
• Tissue paper wrinkling, then large fluid
filled blisters in armpits, groins and around
ears and nose
• Then top layer peels off leaving raw skin
• Causes by exotoxins from certain strains
of staph
• Mortality low but needs intensive care
Staph Scalded Skin Syndrome
• Usually affects small children esp
neonates Red blistered skin like burns or
scalds
• Tissue paper wrinkling, then large fluid
filled blisters in armpits, groins and around
ears and nose
• Then top layer peels off leaving raw skin
• Causes by exotoxins from certain strains
of staph
• Mortality low but needs intensive care
Bacterial
Streptococci
•
•
•
•
•
•
•
•
•
Impetigo (some cases)
Ecthyma (some cases)
Erysipelas
Cellulitis
Scarlet fever
Septicaemia
Erythema Nodosum
Guttate Psoriaisis
Necrotising Fasciitis
Erysipelas
• Erysipelas is an infection of the dermis
and superficial subcutis
• Starts suddenly with inflammation, pain
swelling. High temperature and ill
• It usually has palpable edge
• Beta Haem Strep is usual cause
• Bug enters though minor break in skin
• Face and lower legs are commonest sites
Cellulitis
• Usually caused by Strep
• Similar but deeper and more diffuse than
erysipelas
• Can be very acute with high fever,
vomiting and can be delirious
• If leg involved it can lead to permanent
oedema of leg
• Fungal infections of feet can be the portal
of entry – look for portal of entry
• Need high does of antibiotics to control it
Necrotising fasciitis
• Early signs
– Pain is more than you would expect for
appearance of lesion – agonising pain
– CRP is way up 200 - 400
– often history of taking NSAI drugs like
Ibuprofen
– Personal/family history of strep infection –
throat, impetigo, erysipelas or cellulitis
– Group A Strep NF has higher death rate
than meningococcal disease – up to 23%
Swabs
Accurate prescribing
of antibiotics
Picking up antibiotic
resistance
Finding community
acquired MRSA
WET SWAB
Patients and parents
information
Fusidic Acid
• Resistance to fusidic acid is rising
• Was less than 10% is now 50%
• The resistance is not stable and will fade if
drug stopped
• Fusidic acid must be used for short courses
and stopped and not used regularly. Can be
used for 2 week courses every 6-12 weeks.
MRSA (Methicillin resistant
staphylococcus aureus)
• More resistant to treatment but not
impossible to treat
• Most MRSA in the UK is contracted in
hospital – open sores, operation wounds,
catheter site and I/V sites
• Well people with intact skin are not likely to
contract MRSA
• MRSA can also cause infections in people
outside hospital, but much less commonly –
have been outbreaks in sports teams in USA
Treatment of Skin Infections
• Staph – Oral Flucloxacillin or Erythromycin
250mg – 500mg qds
• Strep – Penicillin V or Erythromycin
250mg – 500mg qds
• Cellulitis – Benzyl penicillin i/m or i/v or if milder
Pen V with Flucloxacillin
or Erythromycin alone if pen allergic
but double doses - 1g qds
Swab for sensitivities
Fish Tank Granuloma
• Caused by atypical mycobacterial infection
• Recreational or occupational exposure to
contaminated freshwater or saltwater
• Affects elbows, knees, feet, knuckles or
fingers
• Often single lump which causes crusty sore
or abscess
• Other lumps on course of lymphatic drainage
• More widespread if immuno-compromised
• Treated with long course of minocycline or
co-trimoxazole 6-12 weeks
Erythrasma
Hyperpigmented, non
scaly plaque in axilla
Due to infection with
Corynebacterium
Common in diabetes
Coral – red
fluorescence with
Wood’s light
Treated with Fucidin,
imidazoles (not
Ketaconazole) and
oral Erythromycin
Lyme Disease
• Borrelia burgdorferi
• A spirochaete - infected Ixodes ticks are
often found on deer
• Erythema chronicum migrans – an annular
erythema expanding outward from the tic
bite
• Have had outbreaks in the New Forest
• If not rx promptly long term serious
sequelae – neurological, cardiac and
arthritic
• Doxycycline for 2-3 weeks, Amoxicillin for
children and pregnant women
Warts
• Most resolve spontaneously
• First Line
– Salicylic acid, Glutaraldehyde, Silver Nitrate,
Formaldehyde soaks and Duct Tape
• Second Line
– Cryotherapy - painful avoid in young children
• Third line
– Surgery, Curette, Efudix, Topical retinoid,
Imiquimod, Laser and PDT
Molluscum
•
•
•
•
•
•
•
•
•
•
Flesh coloured, dome shaped papules
Central dimpling
One of the pox viruses
Can be 1mm to 1cm
Multiple lesions are usual – eczema sufferers get more
Occasional there is just one lesion
An individual lesion lasts 2 months but gets new ones
Lasts 9 months to 15 months
Rarely get it again
If has eczema – moisturise and ease off the topical
steroids in the affected areas
• Worth trying Crystacide – hydrogen peroxide 1%
Orf
Human lesions are caused
by direct inoculation of
infected material. Orf
recovers spontaneously in
3 to 6 weeks. No specific
treatment is necessary in
most cases.
Orf is a parapox virus
infection of the skin
contracted from
young sheep and
goats.
Herpes
• Herpes simplex very common
• Initial infection in childhood is usually trivial but
can be cause of acute gingivostomatis and be
very ill
• Recurrent herpes simplex are common
• Herpes is the commonest recognised cause of
Erythema Multiforme
• Sometimes frequent recurrences needs an
extended course of oral antivirals
Eczema Herpeticum
• Regular polygonal often crusted lesions
• Often a family history of recent herpes if
you take a careful history
• Can go rampant if has widespread
eczema
• Can be life threatening
• It is a ring the dermatologist at the time
scenario – Emergency
Herpes Zoster
If very widespread think
about diabetes, underlying
malignancy or immuno –
suppression
Candida
•
•
•
•
Angular Chelitis in patients with dentures
Red patches on palate in pts with dentures
Intertrigo – small satellite lesions
Candida Paronychia and sub-ungal
infection
• Finger web problems in those doing wet
work
• Severe oral thrush in the immunocompromised
Fungal Infection
• Fungal infections usually have a well
defined edge – unlike eczema
• Tinea Incognito is common with
widespread use of topical steroids
• Eczema of one hand or foot is likely to be
fungal
• Scrapings can help but fungus can be
difficult to culture
Scalp Ringworm
• Affects children
• Rare in adults
• Plaque of short broken hairs with greyish
scale – patchy hair loss
• Microsporum Canis (cats and dogs) is the
commonest
• T.Tonsurans has been imported from the
USA and is commonest amongst AfroCaribbean boys – hair gel and clippers
• Toothbrush scrapings are useful to get
diagnosis
Fungal Treatments
• Topicals – for localised fungal infections
• – Miconazole, clotrimazole etc
• Apply twice daily for two to four weeks,
including a margin of 2-3cm of normal skin
• Continue for 1-2 weeks after rash has cleared
• Oral – for extensive, severe, in hair bearing
areas, resistant to topical and nail treatment
• Terbinafine and Itraconazole
Pityriasis Versicolor
• Superficial yeast infection of torso - malassezia
• Commensal which becomes pathogenic in warm,
humid conditions
• Macules of various shapes and sizes
• Brown - on pale skin
• White on tanned/ pigmented skin
• Fine scale
• Gets mistaken for vitiligo
• Topical azoles e.g ketonconazole or selenium
• Treat with a week of Itraconazole – colour fades
slowly – more effective if takes before exercise
• Can recur
Scabies
• Scabies in babies and toddlers usually affects
feet and hands – often with blisters
• Can be mistaken for eczema
• In women affects nipple area
• In men affects the genitals
• In the elderly and immuno-compromised it can
be very widespread
Distribution of Scabies
Scabies Treatment
• 25% Benzyl benzoate lotion applied daily for 3 days
or
• 5% Permethrin cream left on for 8-10 hours or
• 0.5% Aqueous malathion lotion left on for 24 hours
• Apply whole body from the chin to soles – all body in
under 2years – need to prescribe enough
• Special care between fingerwebs, flexures and
behind fingernails
• The itch will continue 4-6 weeks
• Repeat treatment one week later – overuse will
cause dermatitis
• Oral Ivermectin is now considered treatment of
choice for crusted scabies and other resistant cases.
Lice
• Head lice endemic in school children
• Can get severe eczema on scalp from
scratching
• Red spots on back of neck = head lice
• Need big quantities of clear up an infection
• Vaseline will clear lice in eyelashes
• Combing wet or dry daily for 2 weeks
• Hedrin – dimeticone lotion – new non
insecticide treatment for head lice
Larva Migrans
• Hookworm larvae
• Infests cats and dogs
• Infected by walking barefoot on sandy
beaches or moist soft soil
• Also known as creeping eruption
• Causes itchy red lines/tracks – that move
• Treat with topical thiabendazole or oral
albendazole or Ivermectin
Leishmaniasis
•
•
•
•
From bite of sand fly
Common in the Middle East
Does occur in Mediterranean countries
Lesion is firm papule or nodule which
ulcerates and crusts
• Do heal spontaneously but can scar
• Pentavalent antimonials intralesionally
treatment of choice e.g. sodium
stibogluconate
Leprosy
•
•
•
•
Leprosy caused by Mycobacterium leprae
Found in tropics and subtropics
A spectrum of disease depending on host
Tuberculoid gives skin lesions that are
raised, asymmetrical, anaesthetic and do
not sweat
• Can be pale - mimicing vitiligo or a patch
of eczema
• It is in the UK