Microbial skin disease Flashcards

1
Q

List 3 microbial infections causing pruritus

A

bacterial pyoderma (surface/superficial)
Malassezia dermatitis
Dermatophytosis- variably pruritic - but mostly alopecia

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2
Q

microbial skin infections are very rarely …….

A

a primary problem

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3
Q

List 4 situations when normal skin commensals can cause microbial skin infections

A

Compromise of cutaneous defences
Increased microbial adherence
Changes to skin microclimate
Changes to skin microbiome

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4
Q

what is dysbiosis

A

involves imbalance between types of organism in the microbiome
occurs with surface microbial overgrowths

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5
Q

describe the dysbiosis that occurs in canine atopic dermatitis

A

decrease in bacterial/ fungal diversity
increase in proportion of Staph/ Malassezia

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6
Q

what is the most common organism involved in bacterial pyoderma in dogs

A

staphyylococci pseudintermedius

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7
Q

Describe surface pyoderma

A

Bacteria proliferate on epidermal surface

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8
Q

Describe superficial pyoderma

A

bacteria invade epidermis

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9
Q

List the 4 most common examples of surface pyoderma

A

canine intertrigo (skin fold infection)
acute moist dermatitis (hotspots)
Bacterial overgrowth syndrome
Mucocutaneous pyoderma

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10
Q

Decsribe acute moist dermatitis (hotspos)

A

very acute lesions caused by skin self trauma
triggered by an irritant
very rapid development of bacterial overgrowth

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11
Q

Describe Bacterial overgrowth syndrome

A

Bacterial multiplication with no/minimal inflammation on cytology
highly pruritic - usually involves staphylococci
greasy, malodorous, erythematous, alopecia –> leads to hyperpigmentation and lichenification

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12
Q

Describe Mucocutaneous pyoderma

A

pyoderma on the mucocutaneous junctions

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13
Q

Describe Exfoliative superficial pyoderma (ESP)

A

rapidly expanding erythematous rings with peripheral peeling (epidermal collarettes)
often highly pruritic

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14
Q

Describe impetigo

A

large flaccid pustules up to 15mm diameter, often with erythematous rims

Usually associated with immature immune system/ immunosuppression
occur between hair follicles

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15
Q

what is the most common presentations of pyoderma in cats

A

uncommon in cats
feline achne
surface pyoderma
folliculitis

any of the 4 cutaneous reaction patterns

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16
Q

when is pyoderma a differential in cats

A

any of the 4 feline cutaneous reaction patterns
focal/multifocal alopecia

17
Q

if pyoderma is on our d/d list what do we do

A

cytology- impression smear or stained acetate tape strip depending on lesion
C and S testing occasionally

18
Q

what do we see on cytology with surface pyoderma

A

bacterial overgrowth- Increased numbers of bacteria but no inflammatory cell response

19
Q

what do we see on cytology with superficial pyoderma

A

Degenerate neutrophils, high numbers of cocci

20
Q

List 4 indications for C and S testing when treating pyodermas

A
  1. Superficial pyoderma unresponsive to initial empirical therapy
  2. History of repeated antibiotic use
  3. Previous isolation of a meticillin resistant Staphylococcus (MRS)
  4. Rods seen on cytology
21
Q

How to perform C&S in pyoderma cases

A

sample primary lesions- papules/pustules - direct swab of exudate
secondary lesions- under the crusts or under rim of collarettes
if no primary or secondary lesions- small punch tissue biopsy

22
Q

Describe the general principles of treating pyoderma

A

address infection
use of antipruritic agents? (e.g. corticosteroids)- surface and superficial pyoderma - DON’T USE in dee pyodermas
address underlying disease

23
Q

Describe how to treat acute moist dermatitis

A

Clip lesions (under sedation/GA if painful)
Treat with topical antimicrobial – e.g. chlorhexidine, fusidic acid*
Control pruritus – corticosteroids* usually

24
Q

when do you not use corticosteroids to treat acute moist dermatitis

A

when there are satellite lesions - papules extending out into the hair- suggests deeper infection

25
Q

Describe how to treat surface pyodermas

A

topical treatment only
Chlorhexidine
If not responsive= fusidic acid+/- glucocorticoid

26
Q

Describe how to treat superficial pyoderma

A

topical treatment ONLY is appropriate
chlorohexidine
if not responsive to topical antibiotic therapy- clindamycin

27
Q

what is the most proven antiseptic for dermatological use

A

2-4% chlorhexidine shampoo

28
Q

In cats what is the order for use of Abs for derm use

A

amoxyclav > clindamycin > cephalexin

29
Q

List the 3 main risk factors for development of clinical MRS infections

A

Previous antimicrobial therapy
Repeated visits to vet surgery
Invasive procedures

30
Q

Decsrieb treatment of MRS surface/ superficial infections

A

topical therapy alone
Avoid systemic antibiotics if at all possible (selects for more resistance!)

31
Q

Describe how to treat MRS deep infections

A

Systemic antibiotics, using lowest EMA Category drug shown to be effective (NB never amoxyclav, even if test indicates susceptibility)
Plus topical therapies

32
Q

List the clinical signs seen with Malessezia dermatitis

A

pruritus varies- mild to severe
Initially erythema with greasy exudate, scale, crust –> lichenification, alopecia, hyperpigmentation
+/- rancid malodour

33
Q

Describe how to diagnose malassezia dermatitis

A

cytology- stained acetate tape or direct/indirect impression smear (if moist/waxy)
look like peanut
no fixed number for significance- interpret in light of clinical signs - basically response to treatmet

34
Q

Describe management of malassezia dermatitis

A

topical treatment very effective
often need regular treatment if primary cause can’t be fully controlled as generally a secondary problem

35
Q

List 3 types of superficial pyoderma

A

folliculitis
impetigo
exfoliative superficial pyoderma

36
Q

what is the most common form of pyoderma in dogs

A

folliculitis

37
Q

why are crusts and epidermal collarettes seen more than papules/pustules in superficial pyoderma

A

because the papules/pustules are short-lived primary lesions that turn into crusts/epidermal collarettes

38
Q

you have diagnosed surface pyoderma on the ventrum of a dog, what is the treatment of choice

A

topical 2-4% chlorhexidine shampoo