Bacterial Pyoderma Flashcards by jared Jensen

In dogs and cats, bacterial follicultis and furunculosis are common and they develop

secondary to an underlying disease process

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What are the skin barriers

1) Stratum corneum, hair, epidermal turnover
2) Langerhan’s cells, lymphocytes, immunoglobulins
3) Normal skin flora

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bacterial pyoderma is a result of

altered barrier function and altered microenvironment +/- immunosuppression

pathogenic bacterial adhere to, colonize, infect abnormal skin

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What is the most common cause of bacterial pyoderma in cats

Staph aureus

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What is the most common bacterial pyoderma pathogen

Staphylococcus pseudintermedius- about 90%

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What are the common Staph pathogens causing bacterial pyoderma

Staphylococcus pseudintermedius
Staph. aureus
Staph schleiferi
Staph epidermidis
Coagulase negative Staph?

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What are common secondary bacterial invaders that colonize abnormal skin

Gram Negatives: E. coli, Proteus sp, Pseudomonas sp

Gram Positives: Corynebacterium sp, Streptococcus sp

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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

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T/F: pyodermas are never primary

true

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Another word for skin fold dermatitis

intertrigo - may not be true infection

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What is another word for hot spots

Pyotraumatic dermatitis / Acute moist dermatitis

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Superficial pyoderma is bacterial pyoderma in the

epidermis

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Deep pyoderma is bacterial pyoderma in the

dermis/SQ

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anatomical defect that creates the environment for bacterial proliferation
ex:
facial, lip, vulvar, tail, mammary and body folds

Intertrigo

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What does intertrigo present like

erythema
moist exudate
alopecia
+/- pruritus, malodor

*In the fold (facial, lip, vulvar, tail, mammary, body)

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What folds can intertrigo be in

Facial
Lip
Vulvar
tail
mammary
body

anatomical defect creates environment for bacterial proliferation

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T/F: Pyotraumatic dermatitis (Hot spots) pop up over night

True- they truly do

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How does Pyotraumatic dermatitis present

Alopecia, erythema, erosion, ulceration, exudative, prurutus
*well demarcated from normal skin - no satellite lesions
occur on caudodorsum and face

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Where does Pyotraumatic dermatitis typically occur

caudodorsum
face

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What typically causes hot spots

allergies, ectoparasites

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How do you treat Pyotraumatic dermatitis

1) treat underlying cause- allergies, ectoparasites, otitis external?
2) Topical therapy: 2-4% chlorhexidine
3) Clip area wide

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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”

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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

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infection that begins in the hair follicle and spreads peripherally under the stratum corneum

folliculitis (superficial pyoderma)

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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