Bacterial Pyoderma Flashcards
In dogs and cats, bacterial follicultis and furunculosis are common and they develop
secondary to an underlying disease process
What are the skin barriers
1) Stratum corneum, hair, epidermal turnover
2) Langerhan’s cells, lymphocytes, immunoglobulins
3) Normal skin flora
bacterial pyoderma is a result of
altered barrier function and altered microenvironment +/- immunosuppression
pathogenic bacterial adhere to, colonize, infect abnormal skin
What is the most common cause of bacterial pyoderma in cats
Staph aureus
What is the most common bacterial pyoderma pathogen
Staphylococcus pseudintermedius- about 90%
What are the common Staph pathogens causing bacterial pyoderma
Staphylococcus pseudintermedius
Staph. aureus
Staph schleiferi
Staph epidermidis
Coagulase negative Staph?
What are common secondary bacterial invaders that colonize abnormal skin
Gram Negatives: E. coli, Proteus sp, Pseudomonas sp
Gram Positives: Corynebacterium sp, Streptococcus sp
Why does bacterial skin infection (pyoderma) present with a variety of lesions (ie papules, crusts, epidermal collarettes) and can appear in different places
1) Pyodermas are never primary
2) Pyodermas evolve
T/F: pyodermas are never primary
true
Another word for skin fold dermatitis
intertrigo - may not be true infection
What is another word for hot spots
Pyotraumatic dermatitis / Acute moist dermatitis
Superficial pyoderma is bacterial pyoderma in the
epidermis
Deep pyoderma is bacterial pyoderma in the
dermis/SQ
anatomical defect that creates the environment for bacterial proliferation
ex:
facial, lip, vulvar, tail, mammary and body folds
Intertrigo
What does intertrigo present like
erythema
moist exudate
alopecia
+/- pruritus, malodor
*In the fold (facial, lip, vulvar, tail, mammary, body)
What folds can intertrigo be in
Facial
Lip
Vulvar
tail
mammary
body
anatomical defect creates environment for bacterial proliferation
T/F: Pyotraumatic dermatitis (Hot spots) pop up over night
True- they truly do
How does Pyotraumatic dermatitis present
Alopecia, erythema, erosion, ulceration, exudative, prurutus
*well demarcated from normal skin - no satellite lesions
occur on caudodorsum and face
Where does Pyotraumatic dermatitis typically occur
caudodorsum
face
What typically causes hot spots
allergies, ectoparasites
How do you treat Pyotraumatic dermatitis
1) treat underlying cause- allergies, ectoparasites, otitis external?
2) Topical therapy: 2-4% chlorhexidine
3) Clip area wide
superficial pyoderma that occurs in puppies <1 year of age
infection beneath the stratum corneum in non-follicular areas (axilla and inguinal regions)
usually asymptomatic; usually no identifiable underlying cause
treat with topical therapy
Impetigo “puppy pyoderma”
Impetigo
“Puppy Pyoderma”
superficial pyoderma that occurs in puppies <1 year of age
infection beneath the stratum corneum in non-follicular areas (axilla and inguinal regions)
usually asymptomatic; usually no identifiable underlying cause
treat with topical therapy
infection that begins in the hair follicle and spreads peripherally under the stratum corneum
folliculitis (superficial pyoderma)
What distribution does follicultis typically have
truncal distribution
What are your differentials for for folliculitis *
bacterial pyoderma
dermatophytosis
demodicosis
What might you see with superficial pyoderma
Papules
Pustules
Crusts
Epidermal collarettes
Pruritus
Why might you see pruritus with superficial pyoderma
variable but no one knows why
-Hypersensitivity
-Irritant
-Underlying allergies
-Ectoparasites
Most superficial pyodermas are in the
hair follicle (follicultis)
What is the evolution of pyoderma
1) Papule as it is superficial and in hair follicle (folliculitis)
2) Pustule: papule becomes organized and forms a microabcess
3) Collarette: as the pustule ruptures and infection spreads (exudative +/- dried crusts)
4) Healing- center heals but continue to spreads peripherally (leading edge) which causes erythema, scaling, and alopecia
5) Resolution: as this heals, margins will resolve as well leading to asymmetric resolution “serpiginous”
What are the 3 causes of folliculitis *
1) Bacteria
2) Demodex
3) Dermatophytes
when the bacterial infection extends into the dermis/subcutaneous tissues
Deep Pyoderma
What do you see with deep pyoderma
ulcers, hemorrhage, nodules, draining tracts
How long do you treat deep pyodermas
longer than superficial pyodermas
-Two weeks past resolution
-Average 4-6 weeks
How long to do treat superficial vs deep pyoderma
Superficial: one week beyond resolution
Deep: two weeks beyond resolution
How do you diagnose pyoderma
Impression cytology of crusts
-Cocci (intracellular is gold standard)
-if there’s a lesion and it’s there it’s probably relevant
What kind of bacteria is Staph
Gram + Cocci
What is the gold standard when doing cytology for pyodermas
intracellular cocci- shows that there isnt just an overgrowth but theres and active infection
What rods might be causing the pyoderma when doing cytology
Ecoli
Pseudomonas
Corynebacterium
*Usually more chronic lesions
When considering bacterial pyoderma, what should you do to rule out other primary differentials
-Skin scrapings
-Dermatophyte culture
-Culture
-Biopsy (rule out autoimmune): but treat infection first before biopsy
Before taking a biopsy to rule out autoimmune, you should
treat any bacterial pyoderma first
How do you take a cytology of papule
very hard to do (no sun roof)
but you can take the edge of the slide or use tape
How do you take a cytology of a pustule
25g needle and get impression on the top
but reserve some pustules for biopsy
How do you take a cytology of a collarette
do an impression smear on the exudative margin
How do you take a cytology of a crust
scrape it off and then impression smear
how do you do a cytology of a dry scale
acetate tape preps (margins)
How do you treat pyoderma
1) Treat primary cause (restore skin barrier)
2) Topical therapy preferred (resistance) for superficial infections
3) Systemics if needed (deep, non-compliance, failure of topical monotherapy)
4) Duration
Superficial: one week past resolution (3 weeks)
Deep: two weeks past resolution (4-6 weeks)
For pyoderma, when should you consider systemic treatment
deep
non-compliance
failure of topical monotherapy
How should you treat superficial pyodermas topically
-1 to 2x daily wipes, ointments, sprays (some with steroids)
-2 to 3 x weekly shampoo
resistance theoretically minimized due to concentration of antimicrobial (ie chlorhexidine)
How should you systemically treat pyodermas, if implied (deep, non-compliance, failure of monotherapy)
-Narrow spectrum
-Gram + Staph
-Adverse Effects
-Costs
-Adherence (frequency)
What conferres antibiotic resistance in Staphylococcal spp
PBP2a
What are risk factors of antimicrobial resistance
1) Frequent hospital visits (more exposure to resistant strains)
2) Healthcare family (more exposure to resistant strains
3) Previous antibiotic exposure (ie selection for resistant strains)
All cultures should be performed with
cytology (antibiotic selection)
T/F: culture is not super reliable for topical antimicrobials
true
What should you do to treat pyoderma when the owner does not want to culture
empirical therapy- start with tier I
for routine/empirical use in susceptible pyodermas
Low incidence of adverse effects, fairly well tolerated (expense/adverse effects)
Tier I: 1st generation cephalosporins:
-Cephalexin
-Clavamox
-Clindamycin
What are examples of Tier II antibiotics that if you use them no one is going to complain too much. Maybe slightly higher adverse effect profile or expense. May be a little more broad sprectum
Doxycycline
Cefpodoxime?
What are examples of Tier III antibiotics that have increased chance of adverse effects or accelerated initiation of resistance. Use restricted to culture susceptibility
Fluroquinolones
Cefovecin (Convenia)
What are examples of Tier IV antimicrobials that have severe risk of adverse event. use only as a last resort
-Sulfas/TMS (horses exclusively)
-Chloramphenicol
-Aminoglycosides
-Rifampin
You should not use the Tier IV antimicorbials like Sulfas/TMS, Chloramphenicol, aminoglycosides, and rifampin without
a culture
Staph requires resistance really quickly to ______ because there is only 2 point mutations
Fluoroquinolones
What drugs should you absolutely never use for bacterial pyoderma
Penicillin/amoxicillin
Imipenem
Vancomycin
Linezoid
MRSP is resistant to
all penicillins/cephalosporins
T/F: It is difficult to people to contract MRSP
True
MRSP is _____________ to kill than MSSP but
MRSP is harder to kill than MSSP but not more severe than MSSP
Do you have to separate other dogs when one has MRSP infection
No- other dog is likely already colonized but it isnt going to do anything unless immunosuppressed or skin barrier is compromised from another condition
