Download SkinLecture

Skin infection and infestation
Philip G. Murphy
Consultant Microbiologist, AMNCH, Tallaght
Clinical Professor, TCD
Tel ext : 3919
email : [email protected]
Lecture objectives
•
•
•
•
•
Skin microbiology
Common skin infections
Emergency skin infections
Less common infections
Non-bacterial infections
Normal 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
Resident colonisation
Pathogens 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:
• Fungi:
HS, VZ, Molluscum, Papovavirus, Coxsackie
C. albicans, Microsporum, Trichophyton,
Epidermophyton floccosum
Pathogens 2
• Protozoa:
Leishmania in Africa, Asia S. America
• Helminths:
Onchocerciasis, Loa Loa, Strongyloides
• Arthropod:
Sarcoptes scabiei, Pediculosis (lice)
Skin 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
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
Cellulitis 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
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
Impetigo
Crusted vesicles on face/arms in children
Group 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
Gas Gangrene
Myonecrosis, gas production, sepsis
Microbiological emergency
Rapid onset and toxaemia / shock
Caused by exotoxin-producing
Crepitus, brawny oedema
Clostridium perfringens
Foul-smelling discharge, brown
usually after direct inoculation of
skin discoloration, bullae,
contaminated, ischaemic wound
May advance 1“ per hour!
Disproportionate pain.
Mortality > 25%
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
Gangenous 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)
Ritter’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
Toxic 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.
Pyoderma
•
•
•
•
•
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)
Lyme Disease
Borrellia burgdorferi
Erythema chronicum margans
Rx amoxycillin, 3rd gen cephalosporins
Abscesses
• Subcutaneous: axillae, groin, perineum
postpartum breast
• If foreign body - must remove
• usually Staph. aureus, less commonly Strep.
pyogenes
• Also anaerobes, TB,
• Rx: Drainage +/- antibiotic
Paronychia
• 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
Animal bites
• Pasturella multocida Rx: penicillins
+/- anaerobes
• Others: Tetanus
Rabies
Cat scratch fever
(Bartonella hensellae)
Others
• 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 margins
in Lyme Disease
Other viral
•
•
•
•
Warts: Papovavirus
Molluscum contagiosum: Pox virus
Orf, Milker’s Nodule: Pox viruses
Fifth Disease: Parvovirus
Varicella zoster(chickenpox)
Measles
Erythyma infectiosum
(Fifth Disease
or slapped cheek syndrome)
Molluscum contagiosum
Fungal
• 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
Tinea pedis - usually between toes
Dermatophyte infection:
Trychophyton rubra, T. mentagrophytes, T. floccusum
Infestations
• 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
Varicella Zoster
Nappy rash
Candida albicans
not amoniacal
Candida nail infection
Roseola infantum
viral, incubation 10-15 d
follows sore throat and fever - mistaken for pen allergy
Leishmania tropica
dog, sandfly hosts
Kawaski disease
? Infectious
platelates raised, desquamation
coronary artery aneurysms
Herpes Zoster (shingles)
“ampicillin rash” seen in 2/3 rd’s
of patients with infectious mononucleosis
on ampicillin for “sore throat”
Scalp ringworm
Trichophyton tonsurans
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.
Factitious Ulcer
Self induced
Young adults
HCW or associated with
No distress
Easy reach of dominant hand
Personality:
infantile,dependent,manipulative
Film “The Secretary”
Erysipelothrix rhusiopathiae
Orf / Molluscum contagiosum
Anthrax
Sarcoptes scabei
Leprosy
Lymphogranuloma venereum:
Chlamydia
Bedbug (cimex leticularis)
Chancroid : Haemophilus ducreyii