BACTERIAL SKIN DISEASES : DEEP BACTERIAL PYODERMA
- At a glance
- WHAT DOES IT LOOK LIKE?
- WHAT ELSE LOOKS LIKE THIS?
- HOW DO I DIAGNOSE IT?
- HOW DO I MANAGE IT?
- COMMENTS
What is it?
- A deep bacterial infection of the epidermis and hair follicle leading to rupture of the follicle and development of furunculosis and cellulitis. Occurs secondary to allergic, parasitic (especially demodicosis), endocrine, autoimmune, actinic, neoplastic, pressure point, post-grooming or self-traumatic disorders
- Staphylococcus pseudintermedius is the most common causative organism; S. schleiferi, S. aureus, Pseudomonas sp. and other gram negative bacteria may also occur
- Staphylococcal antibiotic resistance can occur especially in patients with chronic infections and after multiple antibiotic courses
- Common in dogs, rare in cats
WHAT DOES IT LOOK LIKE?
- Can occur in any breed of dog; most frequent cause is generalized demodicosis
- Clinical signs include pustule, papule, crust, erosions, ulcer, draining tracts with serosanguinous, hemorrhagic and/or purulent discharge; hemorrhagic bullae, reddish-purple tissue discoloration, and cellulitis
- Lesions may be focal, multi-focal, or generalized and are described by location and lesion: pododermatitis, elbow callus pyoderma, nasal pyoderma, chin acne, acute pyotraumatic dermatitis (hot spots in long haired breeds), acral lick furunculosis and post-grooming furunculosis
- Larger heavier breeds are more prone to pressure point deep pyoderma. Some German shepherd dogs have a genetically based generalized folliculitis/ furunculosis
- Post-grooming furunculosis is a subclass of deep pyoderma caused by a combination of microtrauma to the dorsal skin and Pseudomonas sp. contamination of shampoo1
- The full extent of skin lesions may be difficult to appreciate until the hair is clipped
- Lesions are often painful but may be pruritic; lymphandenopathy is common
- Patients may be febrile, depressed, and anorexic if septicemia present
WHAT ELSE LOOKS LIKE THIS?
- Demodicosis
- Deep fungal infection including pythiosis
- Actinomycosis,
- Nocardiosis
- Mycobacteriosis
- Autoimmune and immune-mediated dermatoses
- Eosinophilic folliculitis and furunculosis (Well’s syndrome)
- Neutrophilic folliculitis and furunculosis (Sweet’s syndrome)
- Actinic dermatitis
- Cutaneous neoplasia
HOW DO I DIAGNOSE IT?
- Skin scrapings to rule-out parasites such as Demodex
- Fungal culture to rule-out deep fungal infection
- Skin cytology by performing an impression smear of pustule, papule, crust or draining tract fluid: pyogranulomatous to suppurative inflammation with bacterial cocci and/or rods
- Bacterial culture/susceptibility testing using fresh purulent discharge or a macerated tissue biopsy
- Skin biopsy for dermatohistopathology to rule out other diseases; in deep pyoderma shows deep pyogranulomatous to suppurative inflammation with folliculitis, furunculosis, panniculitis and cellulitis; bacteria may or may not be seen
HOW DO I MANAGE IT?
- Systemic antibiotics should be selected based on culture and susceptibility testing as resistant infections are common
- Consider fluoroquinolones and clindamycin as they are carried to the source of infection by white blood cells and are not inactivated by purulent debris2,3
- Antibiotics therapy may be needed for up to 8 weeks or longer in refractory cases4,5
- Systemic antibiotics should be combined with frequent antibacterial topical therapy4,5
TABLE 1. Antibiotics for Treatment of Deep Bacterial Pyoderma | ||
---|---|---|
DRUG | DOSAGE(mg/kg) | DOSE INTERVAL |
amoxicillin trihydrate / clavulanate potassium | 12.5 | q 12 hours |
cephalexin | 22 - 30 | q 8-12 hours |
cefovecin sodium | 8 | subcutaneous, q 14 d |
cefpodoxime | 5-10 | q 24 hours |
chloramphenicol | 40 - 50 | q 8 hours |
clindamycin | 5.5 - 11 | q 12 hours |
doxycycline | 5 10 |
q 12 hours q 24 hours |
enrofloxacin | 5 - 20 | q 24 hours |
erythromycin[MH1] | 10[MH2] -20 | q 8 hours |
marbofloxacin | 2.75 – 5.5 | q 24 hours |
orbifloxacin | 2.5 | q 24 hours |
trimethoprim / sulfadiazine | 15-30 | q 12 hours |
- Chlorhexidine baths or whirlpool soaks daily to every other day initially, then at least twice weekly once infection significantly improved.How to give a medicated bath. Alternative includes benzoyl peroxide baths and 0.5% sodium hypochlorite spray or soaks
- Chlorhexidine sprays and wipes 1-3 times daily on affected areas in between baths may be useful
- Protective padding/ booties helpful for pressure point, acral lick furunculosis and pododermatitis forms of deep pyoderma
Tips
- Identify and manage the underlying cause by performing a thorough diagnostic work-up
- Perform bacterial culture and susceptibility in all patients prior to choosing an antibiotic
- Skin biopsy for dermatohistopathology is helpful in confirming the diagnosis and ruling out fungal, allergic, autoimmune, actinic and neoplastic differentials
- Use antibiotics that penetrate well into granulomatous tissue and treat for long enough
- Incorporate aggressive topical therapy into both initial and long-term treatment plans
- Control flare factors during treatment such as underlying atopic dermatitis, food allergy and flea allergy
- Consider referral to a local dermatologist for severe, resistant or recurrent cases
- www.wormsandgermsblog.com for infection control information and client hand-outs on methicillin resistant Staphylococcus infections
- www.mrsainanimals.com/BSAVA.htmlfor information on methicillin resistant Staphylococcus infections
- Hand-out on infection control for veterinary hospitals
- Weese JS et al. Methicillin-resistant Staphylococcus aureus and Staphylococcus pseudintermedius in veterinary medicine. Vet Microbiology 140 (2010):418-429.
- 1.Hillier A et al. Pyoderma caused by Pseudomonas aeroginosa infection in dogs: 20 cases. Vet Dermatology 17(2006):432-439
- 2. Boothe DM. Small Animal Clinical Pharmacology and Therapeutics. Saunders, 2001, p.194
- 3. Plumb DC. Plumb’s Veterinary Handbook 6th ed. Blackwell Publishing, 2008, p.209
- 4. Miller WH, Griffin CE. Campbell k. eds. Muller and Kirk’s Small Animal Dermatology 7th ed. Saunders, 2013: 125. 188
- 5. Hnilica KA. Small Animal Dermatology- A Color Atlas and Therapeutic Guide. Elsevier-Saunders, 2011, p. 49
- 6. Veterinary Clinical Advisor. Dogs and Cats. Cote.E. 2nd Ed. Mosby. 2011: 951-953
abscess
A discrete swelling containing purulent material, typically in the subcutis
alopecia
Absence of hair from areas where it is normally present; may be due to folliculitis, abnormal follicle cycling, or self-trauma
alopecia (“moth-eaten”)
well-circumscribed, circular, patchy to coalescing alopecia, often associated with folliculitis
angioedema
Regional subcutaneous edema
annular
Ring-like arrangement of lesions
atrophy
Thinning of the skin or other tissues
bulla
Fluid-filled elevation of epidermis, >1cm
hemorrhagic bullae
Blood-filled elevation of epidermis, >1cm
comedo
dilated hair follicle filled with keratin, sebum
crust
Dried exudate and keratinous debris on skin surface
cyst
Nodule that is epithelial-lined and contains fluid or solid material.
depigmentation
Extensive loss of pigment
ecchymoses
Patches due to hemorrhage >1cm
epidermal collarettes
Circular scale or crust with erythema, associated with folliculitis or ruptured pustules or vesicles
erosion
Defect in epidermis that does not penetrate basement membrane. Histopathology may be needed to differentiate from ulcer.
erythema
Red appearance of skin due to inflammation, capillary congestion
eschar
Thick crust often related to necrosis, trauma, or thermal/chemical burn
excoriation
Erosions and/or ulcerations due to self-trauma
fissure
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
fistula
Ulcer on skin surface that originates from and is contiguous with tracts extending into deeper, typically subcutaneous tissues
follicular casts
Accumulation of scale adherent to hair shaft
hyperkeratosis
Excessive stratum corneum, confirmed via histopathology. This term is often used to describe the nasal planum and footpads.
hyperpigmentation
Increased melanin in skin, often secondary to inflammation
hypopigmentation
Partial pigment loss
hypotrichosis
Lack of hair due to genetic factors or defects in embryogenesis.
leukoderma
Lack of cutaneous pigment
leukotrichia
Loss of hair pigment
lichenification
Thickening of the epidermis, often due to chronic inflammation resulting in exaggerated texture
macule
Flat lesion associated with color change <1cm
melanosis
Increased melanin in skin, may be secondary to inflammation.
miliary
Multifocal, papular, crusting dermatitis; a descriptive term, not a diagnosis
morbiliform
A erythematous, macular, papular rash; the erythematous macules are typically 2-10 mm in diameter with coalescence to form larger lesions in some areas
nodule
A solid elevation >1cm
onychodystrophy
Abnormal nail morphology due to nail bed infection, inflammation, or trauma; may include: Onychogryphosis, Onychomadesis, Onychorrhexis, Onychoschizia
onychogryphosis
Abnormal claw curvature; secondary to nail bed inflammation or trauma
onychomadesis
Claw sloughing due to nail bed inflammation or trauma
onychorrhexis
Claw fragmentation due to nail bed inflammation or trauma
onychoschizia
Claw splitting due to nail bed inflammation or trauma
papule
Solid elevation in skin ≤1cm
papules
Solid elevation in skin ≤1cm
paronychia
Inflammation of the nail fold
patch
Flat lesion associated with color change >1cm
petechiae
Small erythematous or violaceous lesions due to dermal bleeding
phlebectasia
Venous dilation; most commonly associated with hypercortisolism
plaques
Flat-topped elevation >1cm formed of coalescing papules or dermal infiltration
pustule
Raised epidermal infiltration of pus
reticulated
Net-like arrangement of lesions
scale
Accumulation of loose fragments of stratum corneum
scar
Fibrous tissue replacing damaged cutaneous and/or subcutaneous tissues
serpiginous
Undulating, serpentine (snake-like) arrangement of lesions
telangiectasia
Permanent enlargement of vessels resulting in a red or violet lesion (rare)
ulcer
A defect in epidermis that penetrates the basement membrane. Histopathology may be needed to differentiate from an erosion.
urticaria
Wheals (steep-walled, circumscribed elevation in the skin due to edema ) due to hypersensitivity reaction
vesicle
Fluid-filled elevation of epidermis, <1cm
wheal
Steep-walled, circumscribed elevation in the skin due to edema