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Skin infection and infestationSkin infection and infestation
Philip G. Murphy
Consultant Microbiologist, AMNCH, Tallaght
Clinical Professor, TCD
Tel ext : 3919
email : [email protected]
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Lecture objectivesLecture objectives
• Skin microbiology
• Common skin infections
• Emergency skin infections
• Less common infections
• Non-bacterial infections
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Normal skin floraNormal skin flora
• Resident:Coag. Neg. Staph, micrococci, diphtheroids
anaerobes eg propionibacteria
• Transient:environmental contamination
Staph. aureus, gram negatives
survive a few hours, reduced by washing and skin antibacterial substances
Staph aureus carriage: nose - 10-30 % outside hospital
20-60 % in hospital staff
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Resident colonisation
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Pathogens 1Pathogens 1• Staphylococcus aureus
• Streptococcus pyogenes (Group A Strep)
• Other haemolytic Strep• Anaerobes: Clostridia, cocci
• Other bacteria:
Corynebacterium diphtheriae, C. minutissimum,
Erysipelothrix rhusiopathiae, Mycobacteria, Pseudomonas, Treponema, B. burgdorferi
• Viruses: HS, VZ, Molluscum, Papovavirus, Coxsackie
• Fungi: C. albicans, Microsporum, Trichophyton, Epidermophyton floccosum
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Pathogens 2 • Protozoa:
Leishmania in Africa, Asia S. America
• Helminths:
Onchocerciasis, Loa Loa, Strongyloides
• Arthropod:
Sarcoptes scabiei, Pediculosis (lice)
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Skin ulcersSkin ulcers
• vascular ulcers: skin flora No Rx
If pathogens +/- Rx • Pseudomonas aeruginosa - ecthyma gangrenosum• Anaerobes - Meleneys & Fournier’s gangrene• Treponema - chancre• M.tuberculosis - lupus vulgaris• M. ulcerans - Buruli ulcer• Borrelia vincenti - tropical ulcer
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Furuncles (Boils) and Carbuncles
• Boils (furuncles) Staph. aureus lesions in hair follicles or sebaceous glands
• Carbuncles are larger deeper involving >1 hair follicle eg back of neck
• If recurrent check blood glucose.
• Rx flucloxacillin +/- Fusidic acid etc.
+/- drainage
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Cellulitis and ErysipelasCellulitis and Erysipelas
• Spreading erythema and swelling
Erysipelas when intradermal
and due to GpAStrep
• 90% Haemolytic Strep (Group A)
• 10% Staphylococcus aureus• ? Anaerobe involvement
Rx: Penicillin + Flucloxacillin
Clindamycin + Ciprofloxacin
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Folliculitis
• Infection of hair follicles
– usually pustular folliculitis
• Clinical presentation
– follicle-centred pustules
– e.g. in scalp, groin, beard & moustache (sycosis barbae)
• Mostly (95%) due to Staphylococcus aureus
• Treatment: oral flucloxacillin
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Impetigo
Crusted vesicles on face/arms in childrenGroup A Strep. (Strep. pyogenes)• +/- Staphylococcus aureus 2o infection• infectious• Impetigo neonatorum = Bullous impetigo
due to Staphylococcus aureus (Group II, PT 71)
Rx: isolation, skin disinfection, antibiotic if severe
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Microbiological emergencyCaused by exotoxin-producing Clostridium perfringensusually after direct inoculation of contaminated, ischaemic wound
Gas Gangrene
Myonecrosis, gas production, sepsis Rapid onset and toxaemia / shock
Crepitus, brawny oedemaFoul-smelling discharge, brown skin discoloration, bullae, May advance 1“ per hour!Disproportionate pain.Mortality > 25%
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Necrotising Fasciitis
Fig 1 Young woman presenting with cellulitis of her lower abdomen after a caesarean section five days earlier. Small areas of skin necrosis are clearly visible
Fig 2 Late signs of necrotising fasciitis with extensive cellulitis, induration, skin necrosis, and formation of haemorrhagic bullae
Rx Surgery + Penicillin & Clindamycin
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Gangenous cellulitisGangenous cellulitis
• Necrotising fasciitis– Type I polymicrobial (GNB, AnO2)– Type II Gp A Strep
• Gas gangrene, (Clostridium perfringens)
• Progressive synergistic gangrene (post op)
• Synergistic necrotising
• Immune compromised (Pseudomonas)
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Ritter’s DiseaseRitter’s Disease or Toxic epidermal necrolysis, or Lyell’s Syndrome
or scalded child syndrome
• Toxaemia, fever,
• erythematous, tender skin lesions
• Staph aureus Group II PT71
• toxin induced split epidermis
Rx: Isolation, Skin disinfection, flucloxacillin
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Toxic Shock SyndromeToxic Shock Syndrome
• Fever, rash, hypotension, GIT signs,
myalgia, confusion, desquamation
• genital or non genital
• TSST-1 or enterotoxin
• 30% recurrence with low TSST-1 Ab
• Flucloxacillin, Ig.
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PyodermaPyoderma
• Skin lesions due to Strep. pyogenes /Staph. aureus• Scrum pox, scabies, eczema, herpes• nephritogenic strains (M types 49, 55)• Gangrene• Rx: debridement
+ antibiotics
(necrotizing fasciitis
Fournier/Meleneys)
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Lyme DiseaseBorrellia burgdorferi
Erythema chronicum margans
Rx amoxycillin, 3rd gen cephalosporins
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AbscessesAbscesses
• Subcutaneous: axillae, groin, perineum
postpartum breast• If foreign body - must remove• usually Staph. aureus, less commonly Strep.
pyogenes• Also anaerobes, TB,• Rx: Drainage +/- antibiotic
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ParonychiaParonychia
• Infection of subcutaneous tissue around nailbed• Staph aureus, Strep pyogenes, Herpes simplex
• Chronic form with loss of cuticle due to wet hands
due to gram negatives, or yeasts
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Animal bitesAnimal bites
• Pasturella multocida Rx: penicillins
+/- anaerobes
• Others: Tetanus
Rabies
Cat scratch fever
(Bartonella hensellae)
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OthersOthers• Erysipeloid: Erysipelothrix rhusiopathiae
blue-red discolouration with a sharp edge Rx: pen
• Erythrasma: Corynebacterium minutissimun Rx: Ery
• Acne vulgaris: skin flora ?Rx: Tet
• Lyme Disease: Borellia burgdorferi Rx: amp/cefotax.
• Diphtheria, burns, Anthrax, Leprosy, Yaws, Pinta
Erythema chronicum marginsin Lyme Disease
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Other viralOther viral
• Warts: Papovavirus• Molluscum contagiosum: Pox virus• Orf, Milker’s Nodule: Pox viruses• Fifth Disease: Parvovirus
Molluscum contagiosum
Varicella zoster(chickenpox)
Measles
Erythyma infectiosum(Fifth Disease or slapped cheek syndrome)
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FungalFungal
• Tinea (ringworm): Trichophyton, Microsporum, Epidermophyton
Tinea capitis (scalp ringworm) M. audouini, T. schoenleinii
Tinea corporis (body ringworm) Trichophyton spp.
Tinea pedis (athlete’s foot) T rubrum,T. mentagrophytes var. interdigitalis, E. floccosum
Tinea barbae (beard ringworm) T. verrucosum
Tinea cruris (groin ringworm) T. rubrum, E. floccusum
Tinea unguium (Nail ringworm) T. rubrum
Rx: antigungals: eg. terbinafine, griseofulvin
• Pityriasis versicolor: Malassezia furfur
• Sporotrichosis: Sporotrichium schenckii
• Mycetoma: Actinomyces,Streptomyces, Nocardia
Tinea corporis
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Tinea pedis - usually between toesDermatophyte infection:Trychophyton rubra, T. mentagrophytes, T. floccusum
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InfestationsInfestations• Scabies: Sarcoptes scabiei mite
Norwegian crusted
• Fleas: Pulex irritans (human flea)
Xenpopsylla cheopsis (Rat flea : Plague)
• Lice: Pediculosis
Pediculus capitis (head louse)
Pediculus corporis (body louse)
Pythirus pubis (pubic or crab louse)
May transmit Typhus (Rickettsia prowazeki)
Relapsing fever (Borellia recurrentis)
Rx: 1/2% Malathion topically
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Varicella Zoster
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Nappy rashCandida albicansnot amoniacal
Candida nail infection
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Roseola infantumviral, incubation 10-15 dfollows sore throat and fever - mistaken for pen allergy
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Leishmania tropicadog, sandfly hosts
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Kawaski disease? Infectiousplatelates raised, desquamationcoronary artery aneurysms
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Herpes Zoster (shingles)
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“ampicillin rash” seen in 2/3 rd’s of patients with infectious mononucleosison ampicillin for “sore throat”
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Scalp ringwormTrichophyton tonsurans
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Ecthyma: exudate or crust of a pyogenic infection involving the entire epidermis. Usually the consequence of neglected impetigo caused by Staphylococcus aureus or group A streptococcus. Can evolve from localized skin abscesses (boils) or within sites of preexisting trauma. The margin of the ecthyma ulcer can be indurated, raised, and violaceous. Untreated ecthymatous lesions can enlarge over the course of weeks or months to a diameter of 2 to 3 cm.Staphylococcal and streptococcal ecthyma occur most commonly on the lower extremities of children, the elderly, and people who have diabetes. Poor hygiene and neglect are key elements in its pathogenesis.
Ecthyma gangrenosum: single or multiple, cutaneous or mucous membrane ulcers that are most often associated with prolonged neutropenia, Pseudomonas aeruginosa bacteremia, and other serious bacterial infections. It resembles ecthyma caused by staphylococcal or streptococcal organisms. First presenting as a painless nodular lesion, it quickly develops a central hemorrhagic area that subsequently breaks down to form a large necrotic ulcer.
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Factitious UlcerSelf inducedYoung adultsHCW or associated withNo distressEasy reach of dominant handPersonality: infantile,dependent,manipulativeFilm “The Secretary”
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Anthrax
Erysipelothrix rhusiopathiae
Sarcoptes scabei
Orf / Molluscum contagiosum
Leprosy
Bedbug (cimex leticularis)
Chancroid : Haemophilus ducreyiiLymphogranuloma venereum: Chlamydia