Pyoderma Flashcards
what is pyoderma?
- pyogenic (pus-producing) infection of the skin
- many causative agents!
-Staph is the main player
-but also dermatophilus congolensis, pseudomonas aeruginosa, etc.
-staph aureus in people and horses
-staph pseudintermedius in dogs +/- schleiferi, felis on cats, hyicus on pigs, etc. - SUPER COMMON in dogs (even more than humans)
describe the healthy skin microbiome
varies with site and point in time! like a crowd at a concert, always moving and shifting
what cause the microbiome to lose its balance and shift towards infection with certain microbiome members?
SO many causes; basically any skin disease
- almost all pyodermas are SECONDARY to a primary/underlying problem
-most common underlying cause is allergies!!! - if no underlying problem can be ID despite extensive search, suspicion of a rare primary (idiopathic) pyoderma arises
describe symptoms of superficial pyoderma
Big 3/pathognostic
1. papules
2. pustules
3. epidermal collarettes
plus:
4. crusts, erythema, malodor, pruritis, alopecia
5. lichenification
describe symptoms of deep pyoderma
- furunculosis
- hemorrhage
- ulceration/draining tracts
- swelling
- crusts
- discomfort/pain
- malodor
- alopecia
- pruritis
- scars
how do you prove your clinical suspicion of pyoderma?
- cytology: crucial initial step
-cocci (staph)
-rods (rarely)
-or branching filaments (D. congolensis) - culture: purulent material, tissue
- PCR, sequencing
- biopsy
- response to antimicrobial therapy
how do we treat pyoderma?
depends on the type!
pyotraumatic dermatitis vs intertrigo vs impetigo vs superficial pyoderma (folliculitis, most common form in adult dogs) vs deep pyoderma (furunculosis, cellulitis)
options:
1. topical antiseptics/antibiotics
2. systemic antibiotics
3. surgically: skin folds and deep pyoderma that is not well approachable or treatable without removing infected tissue (usually non-staph in that case)
4. SEARCH FOR UNDERLYING CAUSE OR WILL RECUR
describe pyotraumatic dermatitis/hot spots and treatment
- focal area of superficial pyoderma
- acute onset, intensely pruritic, often painful, moist, erythematous
- clip, clean, apply topical antiseptic and steroid
describe intertrigo and its treatment
- surface pyoderma associated with skin folds
- moisture, friction, inflammation (microbes love and grow)
- clip, clean (if indicated)
-topical antimicrobial +/- topical steroids (wipes) if inflammation present
-surgical fold removal
-address concurrent conditions (cAD)
describe impetigo
- large, non-follicular superficial pustules often in sparsely haired skin areas of puppues
-collarettes (crusts) - bullous impetigo may be seen in immunocompromised older individuals
- staphylococcus can produce exfoliative toxins which can induce acantholysis
- uncommon, can be pruritic
describe folliculitis
- superficial pyoderma due to infection in the hair follicles
- small papules and pustules (small crusts) centered on hair follicles
-chronic: alopecia, hyperpigmentation - axillary and groin areas, abdomen and trunk
- can be itchy, common in dogs
- treatment:
-topical antimicrobial therapy +/- systemic antimicrobials
-clip and clean to access if needed
describe superficial spreading pyoderma
- epidermal collarette: round to polycyclic expanding lesions with periperhal erythema and crusts
- most common canine presentation
- treatment:
-clip and clean and topical antimicrobials
-or systemic
describe furunculosis
- deep pyoderma
- nodules, hemorrhagic bullae, draining tracts, dermal FB reaction
-heals with scars - treatment: clip and clean
-topical antimicrobials + systemic antibiotics
describe cellulitis
- deep pyoderma involving the dermis and panniculus (bad bc no blood vessels in SQ fat)
- tissue swelling/severe inflammation, draining tracts, hemorrhage, pain
- treatment:
-systemic antibiotics
-topical antimicrobials
-need both and for long periods of time
-clip and clean to access if needed
how do you choose what systemic antibiotic to use for pyoderma?
3 tiers
1st tier: primary choice empirical therapy of known or suspected superficial bacterial folliculitis (no culture to support diagnosis)
-clindamycin, cephalexin, amixo-clav, TMS
1st or 2nd tier: 3rd gen cephalopsorins (cefovecin, cefpodoxime)
2nd tier: when empirical selection of first tier systemic and topical therapy are not appropriate and when CULTURE indicates susceptibility:
-doxycycline or minocycline
-chloramphenicol
-fluroquinolones
-rifampicin
-aminoglycosides (gentamicin and amikacin)
3rd tier: when first and second tier are not appropriate and CULTURES indicate susceptibility
-linezolid, teicoplanin, vancomycin
-use is strongly discouraged!! these drugs can be considered reserved for treatment of serious MRSA infection in humans
-(ex. 13 year old dog with end stage cutaneous lymphoma that caused secondary pyoderma and owners not ready to say goodbye, think long and hard but could allow use)
usually recommended to treat for one week past clinical resolution of signs for superficial pyoderma or until veterinary recheck so not relying on owner to decide when no more clinical signs
when do you consider taking a bacterial culture for pyoderma?
- new lesions during treatment
- no resolution after 6 weeks of treatment + positive cytology
- intracellular rod-shaped bacteria upon cytology
- <50% improvement of lesions after 2 weeks of treatment
- previous history of MRSA staph infection in the household
what does MRSP or MRSA mean?
- staph resistant to beta-lactam antibiotics by:
-producing beta lactamase enzyme which inactivates the antibiotic or by
-expressing PBP 2a, a penicillin binding protein that the antibiotic cannot attach to - acquire via gene transfer, chromosomal mutations, or selection during antibiotic treatment
- becoming increasingly more common in vet med
=please use topical antimicrobials and find the underlying trigger or a better treatment of underlying trigger than systemic antibiotics!
describe topical therapy for superficial pypderma
- topical therapy can be the sole treatment
- topical antibiotics and antiseptics are bactericidal for MRSA species
- most commonly used topical antiseptic is chlorhexidine
- shampoo therapy generally used 1-3x/week and contact time should be at least 10 minutes
- leave on topical formulations can be used 1-2x daily
AND THEN FIND UNDERLYING CAUSE FOR THE SECONDARY PYODERMA OR WILL NEVER ENDDDDDD
