Dermatology > Pyoderma > Flashcards

Pyoderma Flashcards

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1
Q

How common are folliculitis/furunculosis in dogs vs cats?

A
  • Common in dogs

- True folliculitis and furunculosis are uncommon in cats

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2
Q

What causes folliculitis and furunculosis in dogs?

A
  • Usually secondary to underlying disease like allergies or endocrine
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3
Q

What causes cellulitis and abscesses most commonly in cats?

A
  • Bite wounds
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4
Q

Name 4 normal residents of the skin

A
  • Staphylococcus sp (coagulase negative and positive)
  • Micrococcus sp
  • Streptococcus sp
  • Acinetobacter sp
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5
Q

Transient flora - what do they do?

A
  • Colonize abnormal skin
  • Generally do not penetrate and cause infection
  • Often secondary to Staph infected skin
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6
Q

Examples of gram neg transient organisms?

A
  • E. coli
  • Proteus mirabilis
  • Pseudomonas
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7
Q

Examples of gram pos transient organisms?

A
  • Staph sp (coagulase positive and negative)
  • Corynebacterium sp
  • Streptococcus
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8
Q

Which type of Staph are we most concerned about with skin infections?***

A
  1. Staph pseudintermedius**
  2. Staph. schleiferi (coagulase positive)*
  3. Rarely Staph aureus (think horses and humans)
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9
Q

What should you think if you culture Staph aureus from a skin sample of a dog?

A
  • THINK contamination
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10
Q

Normal resistance mechanism of Staph and implications for antibiotic choice

A
  • Beta-lactamase positive

- Any of the -cillins are ineffective

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11
Q

How long does it take for cells from the stratum basal to turnover and go the stratum corneum again?

A
  • 21 days to turn over
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12
Q

How do keratinocytes help with infection prevention?

A
  • Very tightly packed together

- Langerhans are the surveillance cells to prevent infection

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13
Q

MRSP

A
  • Methicillin-resistance Staph pseudintermedius

- Growing concern in dogs and cats

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14
Q

Skin’s physical barrier to infection

A
  • Stratum corneum, hair
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15
Q

Skin’s physiologic barrier to infection

A
  • Skin cell turnover rate, sebum
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16
Q

Immunologic barriers to infection in skin

A
  • Langerhans’ cells
  • Lymphocytes, etc.
  • Sweat
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17
Q

Bacterial barriers to infection in skin

A
  • Normal bacterial flora
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18
Q

What three types of disease process can happen that predispose to pyodermas?

A
  1. Alteration of barrier function (e.g. allergies)
  2. Alters microenvironment of the skin
  3. SUppresses the immune system
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19
Q

How do pathogenic bacteria invade?

A
  • Adhere to skin, colonize, then infect abnormal skin
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20
Q

What layer is below the dermis?

A
  • Panniculus
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21
Q

What is surface pyoderma?

A
  • SKin erosions with secondary adherence and colonization of abnormal skin surface by coagulase positive staph
  • NOT folliculitis
  • Surface irritation
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22
Q

Is surface colonization folliculitis?

A
  • No
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23
Q

Pathophysiology of skin fold dermatitis

A
  • Anatomical defects create warm moist environment for bacterial adherence and colonization
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24
Q

Clinical signs of skin fold dermatitis

A
  • Erythema, alopecia, exudation within skin folds
  • May be pruritic
  • Have offense odor
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25
Types of skin fold dermatitis
- Facial fold - Lip fold - Vulvar fold - Tail fold - Mammary fold - Obesity fold - Body fold
26
Differentials for skin fold dermatitis?
- Malassezia | - Is it surface colonization or deeper? Did pruritus come first? What is colonizing the surface?
27
Diagnosis of skin fold dermatitis?
- History - PE - Scrape - Surface cytology ("tape", cotton swab, or impression) - response to treatment
28
How do you treat skin fold dermatitis?
- many can be managed medically with shampoos, wipes, sprays, mousse, ointment
29
Products to use for skin fold dermatitis
- Topical abx such as chlorhexidine, mupirocin ointment, benzoyl peroxide - Topical antifungal if cytology reveals yeast - Antifungal/antibacterial combination products - DO NOT use combo produtcs with steroids!
30
Appearance of malassezia?
- Little bowling balls
31
Other treatments for skin fold dermatitis
- Weight reduction if obese (vulvar fold, mammary fold) - Keep fold dry! - May need systemic antibiotics (deeper infection implied!) - Surgery
32
What is a true hotspot?
- Pyotraumatic dermatitis
33
SIgnalment of pyotraumatic dermatitis or hospots
- Thick coated, long haired breeds
34
Clinical signs of pyotraumatic dermatitis
- Alopecia, erythema, exudation, ulceration - Lesion is well demarcated from normal skin - Pruritus and pain - SUmmer months on caudal dorsal back (think flea allergy)
35
Pathophysiology of pyotraumatic dermatitis
- Self trauma | - Rule out underlying causes - why is the dog scratching?
36
What should you be considering with pyotraumatic dermatitis as a idfferential?
- Fleas #1 - Allergies - Other ectoparasites (e.g. demodex)
37
2 questions you must answer to diagnose pyotraumatic dermatosis
- Is this a surface colonization or deeper infection? (lesions around the face are usually deep lesions, not true hotspots) - If surface, is it colonized by a bacteria or yeast?
38
Diagnosis of pyotraumatic dermatitis
- PE - SKin scraping (r/o demodicosis) - Cytology - response to treatment
39
Treatment of pyotraumatic dermatitis
- Treat underlying cause for pruritus (e.g. flea control!) - Clip and clean - TOpical antibiotics - Astringents - Antipruritus - True surface colonization does not require systemic antibiotics, but most are no true surface infections
40
Abx to use for pyotraumatic dermatitis?
- Chlorhexidine (spray, wipes, shampoo, mousse) | - Mupirocin ointment
41
Antipruritics to use for pyotraumatic dermatitis
- Topical anesthetics (lidocaine, pramoxine) - Oral steroids - Cytopoint - APoquel
42
Definition of superficial pyoderma
- Infection restricted to under the stratum corneum or within the ostia of the hair follicles
43
What is impetigo?
- Puppy pyoderma
44
Where is the infection (in the dermis and distribution) with impetigo?
- Just beneath the stratum corneum of the non-haired areas | - AXILLAE and inguinal region
45
Underlying causes for impetigo
- Parasitism - Viral infections - Dirty environment - Poor nutrition
46
Are dogs with impetigo usually pruritic?
- Not usually
47
Lesions in dogs with impetigo
- Papules - Pustules - Crusts - Epidermal colarettes - Crusted papules - Hyperpigmented macules
48
Distribution of lesions with impetigo
- Axilla and inguinal region
49
Age of dogs with impetigo
- <1 year of age
50
What should you think if impetigo recurs?
- Food allergies | - It's not normally recurring
51
Diagnosis of impetigo
- Hx, physical exam - Scrapings to rule out demodicosis - Cytology shows neutrophils with bacterial cocci - Response to tx
52
Dfdx for impetigo
- Demodicosis and dermatophytosis
53
Treatment for impetigo
- Can be self limiting - Topical (chlorhexidine or mupirocin ointment) - Systemic antibiotics
54
What is folliculitis/
- Superficial bacterial folliculitis | - This is often referred to as pyoderma
55
Where does folliculitis start?
- Ostia of a hair follicle and spread outward under the stratum corneum
56
Ostia
= Entrance of the hair follicle
57
Clinical signs of folliculitis
- Papules, pustules, crust, epidermal collarettes, patchy alopecia ("moth-eaten" especially in short coated breeds which can be mistaken for hives
58
Distribution of folliculitis lesions
- VENTRUM!** - Ventral chest - Axillae - Ventral abdomen - Inguinal region Can be dorsum and trunk Usually spares legs and head
59
Pruritus with folliculitis
- Variable - Not to the point where he would use steroids usually - May be hypersensitivity to a component of bacteria - May be irritating - May have concurrent or underlying allergy - May have ectoparasites
60
Should you always use steroids with pruritic folliculitis?
- No | - Steroids would be contraindicated if pruritus resolves with antibiotics
61
Pathophysiology of bacterial folliculitis
- Something has altered the natural barrier to infection; frequently secondary to underlying cause (often allergies and endocrine)
62
Pruritic causes of bacterial folliculitis
- Allergies (flea, food atopy) | - Parasites (scabies, cheyletiellosis)
63
Non-pruritic causes of bacterial folliculitis
- Parasites (demodex) | - Endocrine (hypothyroidism, Cushing's)
64
Other possible causes of non-pruritic bacterial folliculitis
- Chronic steroid administration - Immune dysfunction - Malnutrition - Environmental factors - Frequent bathing - Hihg-humidity - Poor grooming
65
Differentials for bacterial folliculitis (MAJOR and other)
- Major: Demodicosis or dermatophytosis | - Sterile folliculitis or autoimmune (pemphigus foliaceus)
66
Diagnosis of bacterial folliculitis?
- History and PE (CLINICAL DX) - Skin scrapings to r/o demodex - Cytology shows neutrophils with or without bacterial cocci - Fungal culture (dermatophytosis is uncommon but never wrong to fungal culture) - Response to tx - Bacterial culture if resistance is suspected
67
What should you think with papules, pustules, and crusts on the ventrum?
Pyoderma
68
Skin biopsy for follicultiis?
- SHouldn't be necessary for diagnosis of superficial pyoderma
69
What is superficial folliculitis (epidermal collarettes) often misdiagnosed as?
- Dermatophytosis
70
Distribution of superficial bacterial folliculitis?
- Focal - Multifocal - Generalized
71
Cytology sample for superficial bacterial pyoderma
- Intact pustules - Crust - Epidermal collarettes
72
What is the definition of pyoderma on cytology?
- Neutrophils (with bacteria is ideal
73
Should you use steroids for superficial bacterial pyoderma?
- DO NOT USE
74
Treatment for superficial bacterial pyoderma (focal)?
- Focal - topical (chlorhexidine or mupirocin) until infeciton/lesions resolve (e.g. 2 weeks)
75
Treatment for superficial bacterial pyoderma (multifocal)?
- Topical +/- systemic antibiotics
76
Treatment for superficial bacterial pyoderma (generalized)?
- Systemic antibiotics +/- topical
77
How long to treat with systemic antibiotics for superficial bacterial pyoderma
- 1-2 weeks beyond clinical resolution - usually 30 days/3-4 weeks total - D o not undertreat or underdose
78
Do the different % of chlorhexidine matter for skin stuff?
- not as much
79
What are the first tier class antibiotics?
- Beta lactams - Cephalexin - Cefpodoxime - Cefovecin (Convenia) - Amoxicillin with clavulanate - he doesn't use this
80
Topical types
- Shampoos - Medicated wipes - Sprays - Mousse - Leave on conditioners
81
How to decide which type of topical to use?
- Think about your patient
82
Signs of steroids on the skin?
- Milia - Comedomes - Dermal atrophy
83
Cephalexin activity
- Good against staph (gram pos) and little activity against gram-neg
84
Side effects of cephalexin
- GI upset
85
Cefpodoxime spectrum of activity
- Same as cephalosporin but more exposure against gram neg
86
Cefpodoxime side effects relative to cephalexin
- Fewer GI side effects
87
Convenia or cefovecin - how administered? how long does it last?
- Administered SQ | - 10-14 days and repeat in 2 weeks
88
Clavamox - why shouldn't you use it?
- many failures seen in his experience due to standard dosage usage (e.g. 13-14 mg/kg)
89
What dose of Clavamox should you use if you decide to go against his advise and use it?
- 20 mg/kg every 12 hours
90
Reasons for treatment failure of superficial bacterial folliculitis?
- Development of bacterial resistance - wrong diagnosis (Demodex, dermatophytosis, autoimmune) - Wrong antibiotic/wrong dose/too short of a course - failure to ID and address underlying cause
91
Underlying causes of superficial bacterial folliculitis
- ALlergies and endocrine!
92
When should you culture for superficial bacterial folliculitis?
- No response to first tier or empirical treatment (if they still have active lesions after 28 days of the 1st line treatment) - Deep pyodermas - Cytology reveals mixed infection (rods and cocci) - Immune suppression
93
How to culture for superficial bacterial folliculitis?
1. Wear gloves 2. Prick pustule or papule with 25g needle and dab with culturette 3. Lift up crust or scale from the collarette with 25g needle and rub culturette under crust or around the rim of the collarette (abrading the keratin) 4. Culture a draining tract (clean off surface first with chlorhexidine and rinse with sterile water, then express material from the tract and place on culturette) 5. Take sterile tissue biopsy (deep pyoderma) - gently prep surface with chlorhexidine and rinse with sterile water, place tissue in red top tube with 1 cc saline and send to lab
94
Resistance mechanisms for Staph
- beta lactamase - Expression of BlaZ gene - Acquisition of mecA gene on SCC mec (penicillin binding protein 2)
95
How to interpret culture results for superficial bacterial folliculitis?
- Make sure you have cultured a staphylococcal organism, especially Staph pseudintermedius or S schleiferi - Resistance to oxacillin = resistance to methicillin = resistance to beta-lactam antibiotics = MRSP?MRSS
96
Second tier class antibiotics - when to use?
- Only based on culture and sensitivity
97
When can you use first tier antibiotics?
- No prior history of antibiotics used OR if previous empirical treatment was effective
98
Examples of second tier antibiotics
- Fluoroquinolones - Clindamycin - TMS - Doxycycline - Rifampin - AMikacin - Chloramphenicol
99
How to decide which second tier abx to use?
- C&S | - Then side effects, and then the cost
100
Third tier antibiotics - when to use?
- Should not be used for ethical reasons | - Reserved for humans tx of MRSA
101
Examples of third tier class antibiotics
- Linezolid | - vancomycin
102
Prognosis for superficial bacterial folliculitis
Depends on ability to find and correct the underlying problem of allergies and endocrine
103
How long can MRSP carry it?
- Anywhere up to a year | - MRSP pyoderma best to reculture if they develop another
104
Prevention of MRSP
- Hand hygiene - Wearing gloves - Disinfection of surfaces - BSAVA guidelines (isolation and barrier protection)
105
What is mucocutaneous pyoderma?
- Superficial pyoderma affecting the lips and perioral skin
106
What usually causes mucocutaneous pyoderma?
- Staph infection
107
Clinical signs of mucocutaneous pyoderma
- Swelling and erythema of lips, especially commissures - Crusting and fissuring may follow - Similar lesions may occur at nares, medial canthus, vulva, prepuce, or anus - Hypopigmentation can be seen
108
Who gets mucocutaneous pyoderma?
- Tends to be German Shepehrds
109
Pathophysiology of mucocutaneous pyoderma?
- unknown | - Doesn't originate in lip folds
110
Primary differentials of mucocutaneous pyoderma?
- Demodicosis** - Autoimmune (discoid lupus erythematosus, pemphigus) - Lip fold dermatitis
111
How can you differentiate mucocutaneous pyoderma secondary to bacteria or autoimmune disease like discoid lupud erythematosus with a secondary infection?
- If you biopsy them in an active state, a pathologist can't differentiate - Often have to differentiate based on clinical response to tx - If you prescribe antibiotics and it goes away, think mucocutaneous pyoderma - If it doesn't think DLE
112
Diagnosis of mucocutaneous pyoderma
- PE - Skin scraping - Cytology - Culture - May be biopsy (better off to treat first and biopsy if disease remains after infection is cleared)
113
Treatment of mucocutaneous pyoderma
- Topical antibacterials (without steroids) - mupirocin or chlorhexidine - Systemic antibiotics for 3-4 weeks; 1 week past clinical remission - Look for underlying cause like allergies or endocrine!
114
What are deep pyodermas?
- Deep infections of deeper regions of the hair follicle, dermis, and subcutis - Includes deep folliculitis/furunculosis and cellulitis - Less common than superficial pyodermas
115
What hsould you always do to diagnose deep pyodermas?
- ALWAYS CULTURE | - May be staph or gram neg bacteria like Pseudomonas
116
Furunculosis
- Nodular dermatitis secondary to a bacterial infection deep in a hair follicle and subsequent rupture of the follicle (furunculosis)
117
Difference between folliculitis and furunculosis?
- Basically the same, but hair follicle ruptures with furunculosis
118
Pathophysiology of furunculosis
- remember that pyodermas are secondary to some underlying disease*** - When the hair follicle ruptures, it releases bacteria, hair, and follicular keratin into the dermis that incites a pyogranulomatous inflammatory reaction
119
Underlying causes of furunculosis
- Basic categories are allergies, ectoparasites, endocrine! - Allergies (flea, food, atopy) - Endocrine (hypothyroidism, Cushing's disease) - Ectoparasites - Inappropriate corticosteroids - Inappropriate antibiotic therapy - Poor nutrition - FB - Immune dysfunction
120
What are bacteria usually with furunculosis?
- Often Staph pseudintermedius | - Can also have Proteus, Pseudomonas, and E. coli
121
CLinical signs of furunculosis
- Papules - Nodules - Hemorrhagic bullae or vesicles - Draining lesions - Cellulitis - Lymphadenopathy - Systemic illness
122
Differentials for furunculosis
- Demodicosis - Fungal infections - FB - Sterile - Neoplasia
123
Dx of furunculosis
- Hx and PE - Skin scrapings to rule out demodicosis - Cytology - C&S (IMPORTANT IN ALL DEEP PYODERMA)
124
Cytology of furunculosis
- Pyogranulomatous inflammation | - +/- bacterial cocci +/- rods (if mixed)
125
C&S for furunculosis
- Important in all
126
Sample type for C&S for furunculosis
- Preferably via tissue bx | - Don't simply swab the surface
127
Canine acne - who gets?
- Short coated breeds (Doberman, Great Dane, English Bulldogs, Boxer)
128
Where do dogs get acne?
- Chin and muzzle
129
Cause of canine acne
- Trauma? Genetics? Puberty?
130
How to prevent canine acne
- avoid or minimize trauma
131
Treatment for canine acne
- Topical or systemic antibiotics in more severe cases
132
Nasal pyoderma - where?
- Bridge of the nose
133
Nasal pyoderma - onset speed?
- Sudden
134
Nasal pyoderma - who gets?
- Dolicocephalic breeds
135
Etiology of Nasal pyoderma
- Trauma? Rooting?
136
Differentials for Nasal pyoderma
- Pyoderma, demodex, dermatophytosis (WITH A CRUST) - Insect hypersensitivity - AUtoimmune (pemphigus foliaceus or erythematosus)
137
Interdigital pyoderma - what causes?
Many diseases! - Allergy - Parasite (Demodex) - Infectious disease (fungal) - Endocrine disease - Sterile (rare) - FB (rare)
138
Lesions for interdigital pyoderma
- Papules, nodules, vesicles, bullae, draining lesions
139
Who gets interdigital pyoderma?
- Short coated breeds
140
Hot spot pyoderma or pyotraumatic folliculitis/furunculosis - what's the difference from pyotraumatic dermatitis?
- Dermatitis created by mouth | - Hot spot pyoderma caused by scratching
141
Lesions of Hot spot pyoderma or pyotraumatic folliculitis/furunculosis
- Areas of plaque-like alopecia with "satellite" papule lesions
142
Where are Hot spot pyoderma or pyotraumatic folliculitis/furunculosis lesions distributed?
- Face and neck - Be a detective and check the ears - SEcondary allergies can cause these too
143
Treatment for furunculosis - what and for how long?
- Systemic antibiotics based on culture and sensitivity for 6-12 weeks or 2 weeks past clinical remission - Look for an underlying cause of pyoderma - Adjunctive therapy includes topical antibacterial shampoo (chlorhexidine)
Dermatology
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