Bacterial Skin Disease Flashcards
What are the various types of cutaneous bacteria?
- Residents (e.g. Staph, Micrococcus)
- they do multiply
- Transients (e.g. E. coli, Proteus mirabilis, P. aeruginosa)
- Do not multiply, competitive with resident bacteria
- Pathogens (e.g. S. pseudintermedius, S. schleiferi)
What are the various types of canine and feline skin flora?
- Staph pseudintermedius
- Staph aureus
- Pasteurella multocida
- Staph simulans
- Staph epidermis
- Staph xylosus
What are the various equine skin flora?
- Staph aureus
- Staph pseudintermedius
- Dermatophilus congolensis
What is an example of porcine skin flora?
Staph hyicus
What are the various physical defense mechanisms of the skin?
- hairs
- stratum corneum
- lipid envelope
What are the various chemical defense mechanisms of the skin?
sebum and fatty acids
What are the various immune defense mechanisms of the skin?
- lymphocytes
- Langerhans cells
- keratinocytes
- cytokines
- AMPs
Which normal cutaneous microbe provides microbial defense for the skin by competition?
Staph epidermidis
Define pyoderma
- bacterial infection within the skin
- can be surface, superficial, or deep and primary or secondary
What are some examples of surface pyoderma
- pyotraumatic dermatitis “hot spot”
- skin fold pyoderma “intertrigo”
How do you describe pyotraumatic dermatitis?
- common
- thick or long hair
- warm weather
- rapid onset
- self-induced
- underlying problem
What are some underlying problems that can lead to pyoderma?
- flea allergy
- ectoparasites
- allergic skin dz
- anal sac dz
- otitis externa
- contact
- ocular
How do you treat pyotraumatic dermatitis?
- Clip and clean area
- Topical astringents and antiseptics
- break the itch cycle
- topical or oral glucocorticoids
- +/- systemic abx
- identify and correct underlying cause
- kill the fleas!
What causes skin fold pyoderma?
- surface infection
- warm, moist folds
- bacteria
- yeasts
How do you treat skin fold pyoderma?
- Medical
- cleaning
- wipes
- Surgical
Describe superficial pyoderma?
- pustules are present in/under the stratum corneum or inside the hair follicles
- e.g. impetigo “puppy pyoderma”, superficial bacterial folliculitis
Describe impetigo
- subcorneal pustules in glabrous ares
- not contagious like human dz
How do you diagnose and treat impetigo?
- Dx: signalment and clinical signs
- Tx:
- topical tx
- ensure clean environment
- severe or persistent cases may need systemic abx
What things cause folliculitis?
- bacteria
- demodex
- dermatophytes
What are three examples of primary skin lesions from bactieral skin disease?
- papules
- pustules
- erythematous macules
What are some secondary lesions that result from bacterial skin diseases?
- circular crusts
- epidermal collarettes
- focal scaling
- alopecia
- hyperpigmented macules
What is the distribution of pyoderma?
- trunk: ventral abdomen
- pruritus is variable - generally present
How do you diagnose folliculitis?
- C/S
- always R/O other causes
- skin scrapings
- cytology
- culture
- biopsy
- response to rx
How do you treat folliculitis?
- antibiotics
- appropriate length of tx
- empirical choice or based on culture and sensitivity
- topical tx
- ID and correct underlying cause!
What are the organisms that cause equine folliculitis?
- Staphilococcus spp.
- Dermatophilus congolensis
What are the clinical presentations of a dermatophilosis infection?
- Strawberry foot rot
- rain scald
- rain rotscald
- rain rot
- lumpy wool
- Streptothricosis
Describe dermatophilosis
- Dermatophilosis congolensis
- Gram + aerobic or facultative anaerobe
- Actinomycete
- Common dz, esp during rainy season
- Horses, cattle, sheep, goats
- Dogs
- potentially zoonotic
What are 3 factors that are important for dermatophilosis to occur?
- Chronic carriers
- zoospores resist drying at 100 deg C
- survives in crusts for 42 months
- Moisture, rain, sweating
- humidity (controversial)
- Break in skin integrity
- trauma, ectoparasites
How is dermatophilosis transmitted?
- mechanical transmission
- flies
- contaminated clippers
- normal healthy skin resistant to infection
What are the clinical features of dermatophilosis?
- dorsal surfaces of animals
- thick “paintbrush” crusts
- hair easily removed exposing moist pink skin
- green exudate and erosions
- more painful than pruritic
- dry crusts, scale, alopecia
How do you diagnose and treat dermatophilosis?
- Dx: clinical features and cytology (railroad tracks)
- Tx:
- self limiting
- remove from rain
- topical
- benzoyl peroxide and chlorohex shampoo
- systemic abx for min of 2 wks
- TMP-Sulfa
- Penicillin
Describe Staphylococcal folliculitis/furunculosis
- Staph aureus
- complication of most pruritic dz
- 3 main syndromes:
- trunk
- tail
- pastern
- no breed, age predilection
Describe truncal folliculitis
- heat rash, saddle rash
- painful papulonodular eruption
- saddle areas and can spread
Describe tail pyoderma
- pustules arise on dorsal area of tail
- induced by tail rubbing
- pruritic
- incr self induced trauma
Describe exudative epidermitis
- caused by S. hyicus
- toxins are absorbed
- liver and kidney dz
- in sucking piglets dz is usually confined to individual animals
Describe deep pyoderma
- furunculosis
- abscess/cellulitis/panniculitis
What is furuncolosis?
- hair follicles rupture and infection spreads to the dermis
- infection may be mixed
What are the clinical signs of furunculosis?
- ulcers
- fistulous tracts
- pustules/bulla
- cellulitis
How do you diagnose furunculosis?
- r/o demodex
- cytology
- culture
- biopsy
- response to abx
How do you treat furunculosis?
- Abx
- appropriate length of tx
- choice based on C&S
- if mult bacteria, address Staph first
- Topical tx
- antibiotic vs antiseptic
- Underlying cause
- allergies, endocrinopathies
- Immunotherapy
- Staphage lysate
- Avoid steroids if possible
Describe subcutaneous abscesses
- result of trauma/wounds/foreign bodies
- common in male cats
- Pasteurella multocida
- establish drainage
- systemic Abx
What are some causes of subcutaneous abscesses in dogs?
- bite wound
- abscessed teeth
- foreign bodies
How do you treat subcutaneous abscesses?
- drainage
- flush
- antibiotics
What antibiotics should be used to treat subcutaneous abscesses in cats?
- penicillin
- amoxicillin/clavulanic acid
What are some recurrent or refractory microbes and substances that can cause skin disease?
- Actinobacillus/Actinomyces/Nocardia
- Yersinia pestis
- Mycobacteria spp.
- Anaerobes**
- Fungi
- Foreign bodies
Describe atypical mycobacteria
- cause opportunistic infections
- recurrent draining tracts and cellulitis
- more common in humid, warm climates
-
cats are quite susceptible
- absence of concurrent immunosuprressive dz
- environmental contamination of wounds
What is the typical clinical history of an animal with atypical mycobacterial infection?
- chronic non-healing wounds
- +/- hx of previous trauma
- poor response to traditional abx tx
- slowly spreading nodular dermatitis, panniculitis
- animal is not sick, despite draining lesions
- +/- lymphadenopathy
Describe “Juvenile Pyoderma”/Canine Juvenile Cellulitis and Lymphadenitis/Puppy strangles
- idiopathic dz
- not a real infection
- immune mediated response
- rule out:
- demodex
- infections
What are the clinical signs of juvenile pyoderma?
- typically young puppies although it may occur in young adults
- edema - face, lips, pinna
- pustules
- lymphadenopathy
- fever
- depression
How do you treat juvenile pyoderma?
- glucocorticoids at high doses
- prednisone 7-10d
- taper over 3 wks
- relapses are possible
- cyclosporine
- common to also use abx to cover for secondary infections
