Infections and Infestations

Dr Iain HendersonGP 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

Can be due to trauma – epilation, occupational due to tar or oils or application of greasy ointments to skin. Pseudomonas from jacuzzis and whirlpools.

Need swabs, Usually Staph if infective. Can have nasal carriage.

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

BacterialStreptococci

• 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

Patients and parentsinformation WET SWAB

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 qdsSwab 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

ErythrasmaHyperpigmented, 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 immuno-

compromised

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 Afro- Caribbean 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