Bacterial Skin Diseases Flashcards
Resident bacteria vs transient bacteria?
- Resident - live/multiply on normal skin and hair shafts
- Transients - grow on/in damaged, unhealthy skin and can become pathologic
Where does Staphylococcus pseudointermedius live on the body normally?
- Normal Flora of:
- mouth
- nares
- inguinal areas
- perianal areas
What is the most common bacterial pathogen of canine skin?
Staphylococcus pseudointermedius
How do staphylococcal bacteria become methicillin-resistant
- Acquire mecA gene - encodes for a low affinity penicillin-binding protein (PBP2a) that results in impaired binding of beta-lactam antibiotics
What diagnostic tests can be ran to determine skin disease cause?
- Cytology (impression smears - bacteria)
- Bacterial culture and sensitivity (species ID)
- Skin scraping (ectoparasites)
- Fungal cultures (fungal infection)
- tests for endocrinopathies (hypothyroidism/hyperadrenocorticism)
- Allergy tests (secondary pyoderma)
- Diet trial (food allergy)
- Skin biopsy
When should bacterial skin disease have culture & sensitivity completed?
- Deep infections
- Infections that are poorly responsive to antibiotics
- When rods are seen in impression smears
- History of methicillin-resistant Staphylococcus
What antibiotic is commonly used for systemic therapy for skin diseases?
- 1st gen cephalosporins (initially/empirically)
- Amoxi-clav (some cases)
- Fluoroquinolones
- Lincosamides
- Potentiated slfonamides
- Chloramphenicol, Doxy, Minocycline, rifampin
- for MRSA based on C&S
What topical therapies exist for bacterial skin infections? how do they work
- Shampoos, conditioners, sprays, ointments,….
- Active ingredients:
- chlorhexidine
- benzoyl peroxide
- ethyl lactate
- triclosan
- bleach
- Shampoos need 10-15mins contact time
- Bathe at leat 2x weekly initially
- massage helps remove scale, exudate, debris and trapped bacteria
- after rinsing, dry thoroughly
What is “glycotechnology”
- Microbial lectins are on the surfaces of yeast and bacteria
- Lectins recognize sugars on the keratinocyte surface leading to adherence
- Exogenous sugars/carbs (in the shampoo) saturate fungal/bacterial lectin binding sites
What are the effects of Benzoyl Peroxide?
- Antibacterial
- “follicular flushing”
- Keratolytic
- Degreasing
- Drying
- Irritating
- Bleaching effect
What are the effects of Chlorhexidine?
- antibacterial
- Antifungal
- Non-drying
- Nonirritating (usually)
- Best for methicillin-resistant Staphylococcus
What is Pyoderma
- Bacterial skin infection
- can be primary or secondary
- classified by location on skin
- surface
- superficial
- deep
What are the common underlying causes of secondary pyoderma
- Allergic dermatitis
- seborrhea
- endocrinopathies
- ectoparasitism
- autoimmune conditions
- other skin conditions
What are the common Surface bacterial skin infections?
- Pyotraumatic dermatitis
- Intertriginous pyoderma
- between skin folds
- Bacterial overgrowth syndrome (surface to superficial)
What is Bacterial overgrowth syndrome?
- Surface to superficial bacterial skin infection
- Typical features of pyoderma (papules, collarettes, pustules, crusts) are lacking
- May only have erythema and pruritus
- Topical therapy alone may be effective
What are common superficial pyodermas?
- Superficial bacterial folliculitis
- Mucocutaneous pyoderma
What are the signs/symptoms of Superficial Bacterial Folliculitis
- Follicular papules
- less commonly pusules
- Crusts
- epidermal collarettes
- hyperpigmentation
- erythema
- patchy “moth eaten” alopecia in short-coated dogs
- Generalized or localized (abdomen, inguinal areas, axillae, caudal thighs)
- some are very pruritic
What is the treatment for Superficial Bacterial Folliculitis?
- Topical antibacterials
- Shampoos
- Rinses, sprays
- Creams, gels
- topical therapy alone may be effective
- Systemic anibiotics may be needed
- 3 week course (or longer)
- Evaluate for underlying causes in recurrent cases
What are the signs/symptoms of Mucocutaneous Pyoderma
- Lips become swollen, erythematous, and crusted
- Commissures of the lips may especially be affected
- May involve eyelids, nares, anus
- May resemble autoimmune conditions (especially DLE)
- Systemic antibiotic therapy may be needed
What are types of Deep Pyodermas?
- Deep folliculitis, furunculosis and cellulitis
- Canine acne
- Bacterial pododermatitis
- German shepherd folliculitis, furunculosis and cellulitis
- Abscess
What is the treatment for Deep Pyodermas?
- Long course of systemic antibacterial therapy
- 4-6 weeks or longer
- Topical antibacterial therapy should be used adjunctively
What are abscesses commonly caused by?
- Commonly caused by cat bites
- Pasteurella multocida commonly isolated
What are some Nontuberculous Mycobacteriosis?
- Feline Leprosy signs
- Canine Leproid Granuloma Syndrome
- Opportunist Mycobacterial Infections
What is canine leproid granuloma
How do dermal infections occur? (MOA)
- Surface adhesion molecules bind host surface receptors on keratinocytes
- ⇢ bacterial colonization of keratinocytes
- ⇢ bacterial skin infection
- ⇢ bacterial colonization of keratinocytes
- form “biofilms” to help protect the bacteria
What bacteria are associated with TSS in dogs?
- Staphylococcal spp.
- Streptococcoal spp.
- Streptococcus canis
Why is MRSA / MRSP a huge concern?
- Interspecies transmission can occur
- Animals/People can be carriers w/ no signs of illness
How is methicillin resistance tested for?
bacterial sensitivity to oxacillin
How does the skin protect itself?
- Stratum corneum is a physical and chemical barrier
- sebum, sweat, fatty acids
- Epidermal cells secrete antimicrobial peptides (AMPs) ⇢ help maintain healthy skin
What factors predispose animals to bacterial skin infections?
- Allergic dermatitis
- Ectoparasites
- endocrinopathies
- environmental conditions (i.e humidity)
- short hair coat
- irritants
- Seborrhea
Why is pyoderma common in dogs?
- thin stratum corneum
- less intercellular lipids
- alkaline pH
Which drugs used for pyoderma are bactericidal?
- Cephalexin and Cefadroxil (1st gen cehpalosporins)
- Cefpodoxime (extended-spectrum cephalosporin)
- Cefovecin (extended-spectrum cephalosporin)
- Amoxicillin-clavulanic acid
- Enrofloxacin
- Orbifloxacin
- Pradofloxacin
- Marbofloxacin
- Trimethoprim-sulfonamides (can be)
- Chloramphenicol (high dose)
- Rifampin
Which drugs commonly used for pyoderma are bacteriostatic?
- Clindamycin
- Lincomycin
- Chloramphenicol
- Doxycycline
- Minocycline
What is astringent therapy?
- Aluminum acetate (Domeboro’s solution)
- Dry agent for certain moist lesions
- e.g. ‘Hot spots’
How is primary pyoderma differentiated from secondary pyoderma?
- No apparent underlying cause of pyoderma
- Usually occurs in otherwise healthy skin
- Can be cured with appropriate therapy
- Less common
How is secondary pyoderma differentiated from primary pyoderma?
- Underlying causes include allergic dermatitis, seborrhea, ectoparasitism
- Affects already diseased/damaged skin
- More than one species of bacteria may be isolated
- Therapy may be less effective and treatment of the underlying cause is necessary
- More common
What is surface pyoderma? examples?
- On skin surface only
- Ex:
- Intertrigo (skin fold dermatitis)
- pyotraumatic dermatitis ‘Hot spot’
What is superficial pyoderma?
- Involves the epidermis and follicular epithelium
- Usually heals without scarring
- Usually doesn’t involve regional lymph nodes and rarely produces systemic signs
- Very common in dogs
What is Deep pyoderma
- Involves the dermis and/or subcutaneous tissue
- May heal with scarring
- Often long, chronic course and may see systemic signs
What are common surface bacterial infections?
- Pyotraumatic Dermatitis
- Intertriginous Pyoderma
- Bacterial Overgrowth Syndrome
What is Pyotraumatic dermatitis? Why does it happen?
- Acute moist dermatitis ‘Hot Spot’
- Intense inflammatory reaction
- Surface bacterial colonization occurs
- Predisposing factors:
- scratching/chewing
- ectoparasites, matted coat, allergies, trauma, foreign bodies, otitis, etc)
- Increased moisture of skin
- Thick-coated dogs in warm, humid weather
- scratching/chewing
What are the clinical signs of pyotraumatic dermatitis
- Well-demarcated, erythematous, moist lesion
- Very pruritic and often painful
- Acute onset
*
How is Pyotraumatic Dermatitis diagnosed?
- History
- Clinical signs
- Impression smear cytology to assess for concurrent pyoderma
How is Pyotraumatic Dermatitis diagnosed?
- Clip and Clean (chlorhexidine, weak providone-iodine)
- Drying agents/astringents
- Topical medication containing an antibiotic and steroid
- Short course (days) of systemic corticosteroids to relieve intense pruritus and irritation
What is intertriginous Pyoderma?
- Skin fold dermatitis or Intertrigo
- Predisposing factors:
- breed
- Conformation
- poor husbandry
What are the clinical signs of intertriginous pyoderma?
- Skin folds are erythematous, eroded or ulcerated
- Lip folds (spaniels)
- facial folds (brachycephalic breeds)
- vulvar folds
- corkscrew tails
- body folds (Shar Pei, obese dogs)
- Odiferous
- Often pruritic
- +/- pain
How is Intertriginous pyoderma diagnosed?
- Clinical presentation
- Impression smear of fold
What is the treatment for Intertriginous pyoderma
- Medical management (keep folds clean/dry)
- Topical antibacterials
- antifungals if yeast is present
- Systemic antibiotics may be needed initially, in severe cases
- Surgical correction to remove folds may be considered
What is Bacterial Overgrowth Syndrome (BOG Syndrome)? why does it occur?
- Can be surface to superficial pyoderma
- Hyperproliferation of bacteria (usually S. pseudointermedius)
- cocci adhere to and colonize corneocytes
- Fairly common
- Usually secondary to underlying skin disease
- especially allergic dermatitis
What are the clinical signs of BOG Syndrome?
- Erythema
- hyperpigmentation
- lichenification
- Usually do Not have papules or crusts
- Pruritus
- Distribution is mainly ventral
How is BOG syndrome diagnosed?
- Clinical presentation
- Impression smear cytology
What is the treatment for BOG syndrome?
- Topical antiseptic shampoos and rinses
- systemic antibiotic therapy may be necessary
What is Superficial Bacterial Folliculitis? How does it develop?
- Bacterial infection of the superficial portion of the hair follicle and adjacent epidermis
- Lead to destruction of the hair with resulting alopecia
- Can progress to hair follicle rupture (furunculosis ) leading to deep pyoderma
- Usually Staph. Pseudointermedius
- Usually secondary to other skin diseases
How is Superficial Bacterial Folliculitis diagnosed?
- Cytology
- Culture (not usually necessary initially when cytology shows cocci)
- Biopsy (especially to evaluate for underlying causes in certain cases)
- Rule out other causes of folliculitis
- especially demodicosis and dermatophytosis
What is the etiology of mucocutaneous pyoderma
unknown
What are the clinical signs of Mucocutaneous Pyoderma
- Lips become swollen, erythematous, and crusted
- Erosions and ulcers may occur in severe cases
- May also see lesions on the eyelids, nares, anus
How is mucocutaneous pyoderma diagnosed
- Clinical presentation
- Cytology
- Biopsy is sometimes done
What is the treatment for Mucocutaneous pyoderma?
- Topical antibacterial ointments
- Systemic antibiotic therapy is usually required
What are the common deep pyodermas
- Deep Folliculitis, Furunculosis, and Cellulitis
- Canine Acne (muzzle folliculitis and furunculosis)
- Bacterial Pododermatitis
- German Shepherd Dog Folliculitis, Furunculosis and Cellulitis
- Feline Abscessation (cellulitis)
What is Deep Folliculitis, Furunculosis, and Cellulitis?
- Hair follicle rupture and spread of infection into dermis
- Usually Staph pseudointermedius
- Usually associated with underlying cause(s)
What are the clinical signs of Deep Folliculitis, Furunculosis, and Cellulitis?
- Papules and pustules
- +/- Hemorrhagic bullae
- +/- Fistulae/oozing tracts
- Circular areas of erythema, scaling, crusting, and alopecia
- Variable pruritus
- More common in dogs
- deep pyoderma of pressure points in large/giant breeds)
- Feline deep pyoderma is Rare
- chin acne may progress to furunculosis
How is Folliculitis, Furunculosis, and Cellulitis diagnosed?
- Cytology (neutrophils usually predominate)
- C&S (deep pyos should be cultured!)
- Biopsy (histopath and deep tissue culture)
- Evaluate for underlying cause
- immunodeficiency, endocrinopathy, etc
- Rule out other causes of similar signs:
- demodicosis
- dermtophytosis
- etc
What is the treatment for Folliculitis, Furunculosis, and Cellulitis?
- Systemic antibiotics for 4-6 weeks
- 2-3 weeks beyond clinical resolution
- Warm soaks/Whirlpools may help
- Adjunctive topical antimicrobial shampoos and rinses
- Correct underlying cause(s)
What is Canine Acne? why does it develop?
- Muzzle folliculitis and furunculosis
- Common inflammatory disorder, usually associated bacterial infection
- affect young dogs (<6mo)
- Affects areas rich in sebaceous glands (chin, lips)
- Hair impaction/trauma may be initiating cause
- Folliculitis may progress to furunculosis or cellulitis
What are the clinical signs of Canine Acne?
- Papulopustular eruptions
- may ooze bloody, purulent discharge
How is Canine Acne Diagnosed?
- Clinical signs are suggestive
- Cytology (neutrophils, macrophages, eosinophils, may not see many bacteria)
- Culture
- Possible biopsy (usually not needed)
- Rule Out: demodicosis, dermatophytosis, contact dermatitis (uncommon)
What is the Treatment for Canine Acne?
- Topical antibacterials
- Systemic antibiotic therapy is necessary for advanced cases
- Mild cases may regress with sexual maturity
- Topical corticosteroids my help prevent recurrence
- decrease the inflammatory reaction
What is Pododermatitis? Why does it occur?
- Dermatitis of the feet
- Numerous etiologies, may occur as a result of underlying causes such as:
- bacterial infection
- parasitism (demodicosis)
- fungal infections
- allergies
- immune mediated conditions
- Irritation
- Trauma
- Foreign bodies
- Furunculosis may develop
- Rare in cats
What are the clinical signs of Pododermatitis?
- One or all feet
- Interdigital pustules, papules, nodules, hemorrhagic bullae
- may have fistulae and interdigital cystic-like lesions
- Serosanguineous and/or purulent exudate
- Feet may be swollen and painful
How is Pododermatitis diagnosed?
- Physical Exam
- Cytology
- Culture
- Possible biopsy
- Work-up for possible underlying etiologies
What is the treatment for Pododermatitis?
- Long term systemic antibiotics based on C&S
- Antibacterial soaks/whirlpools
- especially w/ oozing, exudative tracts
- Surgical debridement, drainage, and curettage may be necessary
- Sterile dermal granulomas may develop after the infection has resolved
- may then respond to therapy such as prednisone or cyclosporine
- Correct underlying cause
What is German Shepherd Dog Folliculitis, Furunculosis and Cellulitis?
- Heritable defect
- possibly autosomal recessive
- Uncommon condition
- once it occurs, relapses are common
- Immunodeficiencies have been demonstrated (lymphocyte subset and immunoglobulin abnormalities, defects in cell-mediated immunity)
- hypothesis: exaggerated tissue response to shaphylococci triggering release of inflammatory mediators
- Lesions triggered by an insult to the skin or occur spontaneously
What are the clinical signs of German Shepherd FFC?
- Middle age dogs, males at increased risk
- Lesions are papules, pustules, crusts
- ALopecia, hyperpigmentation, ulceration and fisulae as disease progresses
- Distribution:
- back, rump, ventral abdomen and thighs
- may become generalized
- May have some degree of pruritus
- Lesions may be painful
How is German Shepherd FFC diagnosed?
- Physical exam (distinctive distribution pattern)
- Cytology
- Culture
- +/- Biopsy
- Evaluate for underlying disease
- Rule out other dermatoses that cause papules and crusting
How is German Shepherd FFC treated?
- Clip and bathe with antibacterial shampoo, whirlpools
- Long term systemic antibiotics
- Immunomodulatory therapy (certain cases)
- May relapse when antibiotics discontinued
- may require maintenance therapy
- Resolve possible trigger factors/other skin disease
What is Cat Abscessation?
- Abscess - Focal accumulation of pus
- Cellulitis - diffuse dermal and subcutaneous infection
- Common in cats
- Secondary to cat bite wounds
- Pasteurella multocida common isolate
What are the clinical signs of Feline Abscessation
- Signs vary from classic, focal abscess to asymptomatic swelling
- Commonly: face, limbs, tail base, back
- Very painful
- +/- Fever
- Other signs:
- pyothorax
- osteomyelitis
- septic arthritis
- sinusitis
- bacteremia
How is Cat abscessation diagnosed
- Physical exam
- Cytology
- Culture
What is the Treatment for Cat Abscessation?
- Drainage and flushing
- warm packs
- Topical antiseptics/antibiotics
- Systemic antibiotic
What are examples of Nontuberculous Mycobacteriosis?
(mycobacterium infections that is not tuberculosis)
- Feline leprosy
- Canine leproid granuloma
- Opportunistic Mycobacterial Infections (Atypical Mycobacterial Infections)
WWhat is Feline Leprosy caused by?
- Mycobacterium lepraemurium, and others species (Aerobic, acid-fast bacilli)
- Rare
- Transmitted by rodent bites and insect vectors
What are the clinical signs of Feline Leprosy
- Cutaneous or subcutaneous nodules or plaques
- Lesions may be solitary or multiple
- Lesions may be ulcerated
- Head and limbs are often affected
- Rarely disseminates to organs
How is Feline Leprosy diagnosed?
- Cytology (acid-fast stains)
- PCR
- Biopsy - intact nodules if possible
- Culture is very difficult
What is the treatment for Feline Leprosy
- Wide surgical excision with antimicrobial therapy
- Combination therapy with antibiotics such as rifampin, clarithromycin, pradofloxacin
What causes Canine Leproid Granulomas?
- Uncommon
- Inoculation route unknown - biting insects?
What are the clinical signs of Canine Leproid Granuloma
- Short-coated breeds
- Cutaneous or subcutaneous granulomatous or pyogranulomatous nodules are often located on the head and dorsal fold of the pinnae
- Otherwise healthy
How is Canine Leproid Granulomas diagnosed
- Cytology (acid-fast)
- PCR
- Biopsy
What is the treatment for Canine Leproid Granuloma?
- Most spontaneously resolve w/in 3 months
- cell-mediated immune response by host
What are Opportunistic Mycobacterial Infections?
- Uncommon/Rare infections of dogs/cats
- Nontuberculous mycobacteria - aerobic, acid-fast bacilli
- Mycolicibacterium fortuituitum
- Mycolicibacterium phlei
- Mycolicibacterium smegmatis
- Mycobacteroides chelonae/abscessus
- M. thermoresistable
- Bacteria inhabit soil/water ⇢ contaminate broken skin and wounds
What are the clinical signs of Opportunistic Mycobacterial Infections?
- Dermal and subcutaneous nodules, ulcers, fistulae
- Lesions frequently located on the ventrum, lumbar region and extremities
How are Opportunistic Mycobacterial Infections diagnosed?
- Cytology
- Culture (exudate from aspirates of affected tissue)
- Biopsy (special stains, PCR testing)
How are Opportunistic Mycobacterial Infections treated?
- Surgical excision of affected tissue
- Antimicrobial therapy (empirical until C&S results)
- Doxycycline
- Fluoroquinolones
- Clarithromycin
- Treated fir 3 - 12 months
Do cats/dogs get Tuberculosis?
- Rare
- Mycobacterium tuberculosis & M. tuberculosis bovis
- Airborne transmission and ingestion of unprocessed meat/milk
- Clinical signs:
- respiratory signs
- Digestive signs
- Cutaneous nodules and ulcers
- Public Health Hazard - euthanasia recommended
