Dermatology - Pyoderma (Bacterial-induced Dermatologic Disorders) Flashcards
What are the primary bacterial pathogens of the skin encountered in small animal practice?
S. psuedintermedius, S. schleferi, S. aureus (in decreasing order of prevalence)
What does staphylococci produce that may induce host reactions or protect the organism?
enzymes (like Beta-lactamase proteases) and toxins (Protein A)
What other bacterial isolates can be found in skin infections?
Proteus, pseudomonas, E. coli, and streptococcal organisms
What about bacterial skin infections favors bacterial growth?
Inflammation of the skin leads to microenvironmental changes (increased temperature and humidity)
What predisposing factors are associated with bacterial skin infections?
signalment, anatomic factors, and environmental factors
What do some breeds have that predispose them to bacterial skin infections?
IgA deficiency
What anatomic factors predispose them to bacterial skin infections?
skin folds and hair coat type
What environmental factors predispose patients to skin infections?
temperature, humidity, frequent swimming by the pet
What is the most common primary underlying cause of bacterial skin infections?
allergies - atopy specifically
What is the second most common primary cause of bacterial skin infections?
endocrinopathies - hypothyroidism (specifically this one) and hyperadrenocorticism
What other primary factors, aside from the top two, are associated with bacterial skin infections?
ectoparasitic infestations, scaling disorders/disorders of cornification, immunodeficiencies, skin trauma or maceration (over hydration)
What lesions are seen in pyoderma?
papules, pustules, epidermal collarettes, erythema, scale/crusts, patchy alopecia, and draining (fistulous) tracts
What is the severity of pruritus in bacterial skin infections?
mild to moderate
What is the classical lesion for superficial folliculitis?
patchy alopecia
What are the differential diagnoses for pustules?
pyodermma, autoimmune skin diseases, dermatophytosis, eosinophilic dermatitis, sterile pyogranulomatous dermatitis, and panniculitis
What is the goal of specific diagnostics for bacterial skin infections?
they are intended to confirm the presence of a bacterial infection, then define the causative organism, and identify the primary (underlying) condition
What specific diagnostics can be used for diagnosing the type of bacterial skin infection?
dermatologic data base, cytology, culture and susceptibility/sensitivity testing, routine hematology, evaluation of the thyroid gland, immunologic evaluations, and skin biopsies
When is a cytology a key diagnostic tool in bacterial skin infections?
whenever pustules, papules, or draining tracts are present
What type of samples should be used for cytologies in bacterial skin infection cases?
they should be collected from intact lesions, such as a pustule, when possible
When is culture and susceptibility/sensitivity testing indicated?
recurring infections, failure of the patient to respond to traditional treatment, when the only bacteria on cytology are rod-shaped organisms, and deep pyoderma cases
What types of topical treatments can be used to treat bacterial skin infections?
Gels, creams, ointments, sprays, shampoo therapy, wipes, and astringents
What are the types of gels,creams, ointments, sprays that are used to treat bacterial dermatitis?
Benzoyl peroxide, mupriocin, povidine-iodine, chlorhexidine
What is Benzoyl Peroxide available as?
a gel and shampoo
What is the best used concentration of benzyl peroxide?
2.5% solution - higher can cause severe cutaneous irritation
Is benzoyl peroxide bactericidal or bacteristatic and for how long?
bactericidal for up to 48 hours after application
What actions do benzoyl peroxide have?
follicular flushing action, keratolytic, astringent, degreasing, a debriding action and promotes wound healing
What bacteria is Mupriocin effective against?
staphylococci and gram negative bacteria
Is Povidine-iodine bactericidal or bacteristatic?
bactericidal
How is Chlorhexidine available?
as sprays and shampoo
What active ingredients in shampoos are effective in bacterial dermatitis?
Most to least active - benzoyl peroxide, chlorhexidine, povidone-iodine, triclosan, sulfur/salicylic acid
Can shampoos be used for sole treatment of bacterial dermatitis?
yes, for mild or superficial infections, or as adjunctive treatment with antibiotics
What are the keys for using shampoos for bacterial dermatitis?
Contact time of 10 minutes, use neutral temperature to slightly cool water, bathe every 2-3 days for sole treatment, every 7-10 days for adjunctive therapy, and every 7-14 days for long term use
If benzyl peroxide is used long-term what should be used in conjunction with it?
conditioners because it is a potent degreasing shampoo
What are wipes indicated to treat?
focal infection (i.e. fold pyoderma, acute moist dermatitis, etc.)
What wipes have antibacterial activity?
Nisin (Preva) and Acetic acid/boric acid (Malcetic wipes)
What are astringents used for in treatment of bacterial dermatitis?
topical drying of moist lesions
What are some common astringents used in treatment of bacterial dermatitis?
Domboro’s solution (aluminum acetate) and TAN-SAL (tannic acid solution)
What antibiotics are a POOR choice for cutaneous therapy of bacterial skin infections?
penicillin, ampicillin (and derivatives), sulfas, tetracycline, and aminoglycosides (cause of toxicity and route of administration)
What antibiotics have INTERMEDIATE value in treatment for cutaneous therapy of bacterial skin infections?
linomycin, erythromycin, some fluroquinolones, potentiated sulfonamides, and chloramphenicol
What antibiotics are HIGHLY effective for cutaneous therapy of bacterial skin infections?
cephalexin/cefadroxil/cefpodoxime, some flouroquinoones, amoxicillin + clavulinic acid, penicillinase-resistant synthetic penicillins (e.g. cloxacillin)
What is the ideal antibiotic for treatment of cutaneous therapy of bacterial skin infections (not a specific antibiotic, this is a generality)?
low cost, bactericidal agents, narrow spectrum of activity (to avoid complications, effective orally, infrequent administration, few adverse effects, penetrates skin well, active in the presence of inflammatory cells, concentrates in macrophages)
What is the suggested time frame for treatment with antibiotics for surface pyoderma?
5-21 days
What is the suggested time frame for treatment with antibiotics for superficial pyoderma (e.g. folliculitis)?
21-30 days
What is the suggested time frame for treatment with antibiotics for deep pyoderma (e.g. furunculosis)?
1-6 months
What types of methods can be used for hydrotherapy?
whirlpools, ultrasonic tubs, or active bathing systems
What does hydrotherapy help to do?
remove surface debris, alleviate discomfort, increased cutaneous blood flow
What condition is hydrotherapy especially helpful in?
deep pyoderma
Is immunotherapy used for bacterial dermatitis?
not commonly anymore
Note—- see other side
doses for antibacterial agents is in the ppt, there are too many and I doubt he will ask the specifics
What are MRS strains recognized to be resistant to?
oxacillin
What MRS strains are found in dogs?
S. pseudintermedius, S. schleferi, and S. aureus
What is the most common source of MRS in dogs?
S. pseudintermedius
True or False: MRSA and MRS are interchangable terms.
FALSE - the term MRSA should not be used for MRS pseudintermedius infections in dogs!!!
Does MR (methicillin resistance) increase virulence or pathogenicity of S. pseudintermedius?
no
If a dog has a MRSA infection, and a human in the household also has one, who gave it to who (typically)?
the human to the dog
What are the categories of pyoderma?
surface pyoderma, superficial pyoderma, deep pyoderma, cellulitis
What is acute moist dermatitis commonly known as?
hot spots
What are the predisposing factors of acute moist dermatitis?
breed of dog, type of hair coat, behavior such as frequent swimming, underlying allergic diseases, nutritional status of the pet, high environmental temperature and humidity, etc.
What primary or initiating factors are associated with acute moist dermatitis?
allergic skin disease, ectoparasites, trauma, or any factor could damage the skin allowing bacterial invasion
What is the most commonly isolated organism of acute moist dermatitis?
Staphylococcus pseudintermedius
What form of pyoderma does acute moist dermatitis start as?
surface pyoderma
What clinical features are associated with acute moist dermatitis?
intense pruritus, focal areas of edema, erythema, alopecia, crusts, ulcers, and matted hair
Why is acute moist dermatitis considered a dermatology emergency?
the lesions develop very quickly
What is the therapy protocol for acute moist dermatitis?
- Clip the region to allow good exposure to air 2. Gently clean the affected area 3. Astringents to dry the lesion 4. Systemic antibiotics for 7-21 days 5. short-term glucocorticoids (1 injection of short or immediate acting, or 7-10 day dose of oral pred)
What dogs are commonly affected by canine acne?
immature dogs and are reported more common in shorthaired breeds
What factors may predispose a patient to canine acne?
undeveloped immune system, nutritional status, or other health issues
What lesions are associated with canine acne?
they range from a few papular eruptions and pustules to severe, progressive folliculitis and furunculosis
Where do papules and pustules typically appear in dogs that have canine acne?
they are on the muzzle and the chin
What permanent lesion is associated with furunculosis?
alopecia and scarring because the hair follicle is damaged
Can any cases of canine acne heal themselves?
yes, mild cases often regress at sexual maturity
What type of therapy may be sufficient for mild cases of canine acne?
topical antibacterial therapy (mupirocin or BPO gel)
How else do you treat canine acne?
daily cleaning of affected area with iodine or chlohexidine shampoos, wiping affected areas with acetic acid/boric acid wipes, and systemic antibiotics
What is another name for skin fold pyoderma?
intertriginous pyoderma
Why are skin folds good for bacterial proliferation?
they provide a warm, dark, moist environment
What are the predisposing factors for skin fold pyoderma?
breed predisposition, conformation, hormonal imbalances, poor husbandry, and allergic skin disease
Where is skin fold pyoderma typically located (specific)?
lip folds, facial folds, vulvar folds, and corckscrew tails
How do areas effected with skin fold pyoderma frequently present?
erythematous, odiferous, and ulcerated
What behavior may a patient with skin fold pyoderma present with?
the animal may rub its face or lick at affected areas
What is the recommended therapy for skin fold pyoderma?
Topical astringents for drying, topical antibiotics for focal lesions, and systemic antibacterials in severe cases
Aside from pharmaceutical management, what else can aid in treatment/prevention of skin fold pyoderma?
surgical correction of conformational problems
What is impetigo also known as?
puppy pyoderma or superficial pustular pyoderma
What is impetigo often secondary to?
improper sanitation, poor diet, coincidental disease states, parasitism
Generally, what bacteria is found in impetigo?
staphylococcus or streptococcus
What age is impetigo seen in?
less than 9 months
What lesions are associated with impetigo?
subcorneal pustular formation which rupture, forming honey colored crusts
How do impetigo lesions progress?
from pustules to crusts with collarette formation
Where are impetigo lesions located primarily?
on the ventrum: abdomen, groin, medial aspects of thighs
What is the recommended therapy for impetigo?
identify and correct underlying causes, topical antibacterials, and systemic antibiotics
What are the three main causes of folliculitis?
demodicosis, dermatophytosis, and staphylococcal infections
What is the most commonly isolated pathogen in patients that have folliculitis?
S. pseudintermedius
What organism is most commonly associated with postgrooming furunculosis?
Pseudomonas aeruginosa
Define folliculitis.
inflammatory reaction of the hair follicle
What lesion does folliculitis lead to?
an accumulation of inflammatory cells, edema in the perifollicular area, resulting in formation of a papule
What can folliculitis progress into (after a papule)?
furunculosis - deep pyoderma
What is the most common predisposing disease to folliculitis?
atopy and hypothyroidism
What dogs are predisposed to folliculitis?
shorthaired dogs
Where does foliculitis typically focus at?
the trunk, chest, and lateral aspects of extremities
What do lesions of superficial folliculitis progress to?
from papules, to pustules, to epidermal collarettes
How does the hair coat typically present in patients with folliculitis?
moth eaten, patchy alopecic hair coat
What level of pruritus is associated with folliculitis?
mild to moderate
What is the recommended therapy for folliculitis?
Appropriate antibiotic therapy for a minimum of 30 days, topical antibacterial shampoos (taper method), identify and control predisposing and primary factors of pyoderma, and antiseborrheic shampoos to reduce crusts and pruritus
How does furunculosis develop?
results from progression of folliculitis caused by bacterial, fungal, or parasitic involvement
What happens when follicles rupture in cases of furunculosis?
The rupture extends the infection and releases highly irritating keratin into the dermis. Sinus or draining tracts develop to extrude the keratinized debris
What are the key lesions to identify furunculosis?
progress to formation of nodules, crusted ulcers, and small draining (fistulous) tracts
What other lesions are associated with furunculosis?
pruritus and alopecia (from ruptured hair follicles)
Where does postbathing/grooming furunculosis typically develop?
in the thoracolumbar regions
What is the recommended therapy for furunculosis?
Appropriate antibiotic therapy for 1-6 months, hydrotherapy to clear up lesions and reduce pain, surgical debridement and lancing, and identify and control of the underlying diseases
What bacterial agent is typically isolated from interdigital pyoderma?
S. pseudintermedius
What dogs are predisposed to interdigital pyoderma?
English bulldogs, dachshunds, boxers, and large breeds
What primary conditions are associated with interdigital pyoderma?
immunodeficiency syndromes, hypothyroidism, allergies, and true follicular cysts
What may suppurative folliculitis and furunculosis in cases of interdigital pyoderma extend into?
cellulitis
What are the differential diagnoses for interdigital pyoderma?
follicular cysts, sterile pyogranulomatous reactions, and foreign bodies
What lesions are associated with interdigital pyoderma?
purulent, exudative, draining tracts of the feet with moderate to severe swelling
What behavioral signs may be associated with interdigital pyoderma?
they may refuse to walk because their feet are so painful
How can interdigital pyoderma be diagnosed?
dermatology data base and cytology, bacterial culture, evaluation of the thyroid
What are the recommended therapies for interdigital pyoderma?
long term antibiotic therapy, whirlpools, surgical debridement and removal of fistulous tracts, and identify and manage primary disease
What may mucocutaneous pyoderma resemble?
autoimmune disease (e.g. pemphigus)
