Infections and Infestations Dr Iain Henderson GP Scotstoun Hospital Practitioner, Western Infirmary
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
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