Cellulitis + Abcess patho Flashcards by Pierre Wadeie

How can SSTI’s (skin and soft tissue infection) be classified based on? (3) Examples

Structure of skin involved (epidermis, dermis, subcutaneous fat and fascia)
Causative pathogen (yeast, lice, chickenpox, acne)
underlying pathology (surgery, diabetic feet with ulcers)

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What are some of the skin barrier defenses (4)

Tight junctions between cells
Relative dryness to prevent bacterial growth
Mild acidity due sebum and sweat.
Constantly being shed to limit the amount of colonization

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What are risk factors for uncomplicated cellulitis? (7)

Obese
Diabetes
Peripheral vascular disease
History of cellulitis

History of chronic venous stasis
Anything causing lymph obstruction: pregnancy, radiotherapy
Damage to physical skin: excessive dryness, cuts, burns, bites

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In most cases of uncomplicated cellulitis and skin abscess, the bacteria introduced under the epidermis are present as ______

Skin colonizers

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What are signs and symptoms of uncomplicatedd cellulitis

Redness that spread
swelling/edema “peau d’orange”,
fluid filled vesicles, warmth and pain
Also lymphangitis, leukocytosis and fever are possible
Symptoms are always UNILATERAL

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Culture in cellulitis?

Skin cultures are useless in cellulitis since skin is colonized with all kinds of bacteria

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What bacteria is often found in cellulitis

Group A strep (lancefield)

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T/F Symptoms of cellulitis are dependent on amount of bacteria

False
- dependant on extent of inflammation

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What are risk factors for Abscess (5)

Diabetes
IV use
contact with individuals with abscess
presences of S.aureus
Immunocompromised

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What is Abscess?

Collection of pus in the dermis or subcutaneous tissue which develops following skin barrier damage or when bacteria travel along a hair follicle.

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Which bacteria is the major cause Abscess? Why?

Staph aureus
- due to its virulence factors that induce purulence and abscess

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What are symptoms of abscess

Swollen, red, warm to the touch, and often painful.
- It may feel soft and fluctuant, indicating pus accumulation
- May appear above skin level and topped off with a pustule
May be below skin level and only redness will be seen on the surface

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What are red flags of cellulitis and abscess (8)

Rapid spread
Sloughing skin (shedding)
Disproportionate pain
Widespread ecchymoses
Anesthesia of involved
Significant systemic toxicity
Localization over or inability to move joint
Hard, wooden feel of tissue

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Differentiate between stasis dermatitis and cellulitis
Distribution
Onset
Clinical symptoms
Systemic symptoms

Distribution
- Stasis: Bilateral, often in medial ankle
- Cell: UNIlateral, broad lower spectrum

Onset
- Stasis: chronic
- Cell: Few hours to few days

Clinical symptoms
- Stasis: Usually pruritic, eczematous, red-brown pigmentation
- Cell: Erythema, tender and warm, shiny

Systemic symptoms
- Stasis: none
- Cell: can occur

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What are exclusions of uncomplicated cellulitis (8)

Abscess
Cirrhosis
Necrotizing
Facial cellulitis
Immunocompromise
Presence of microbiological modifiers
Surgical site infection, chronic wound/ ulcer
Deeper involvement (eg. fascia, muscle, etc.)

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What are symptomatic management of uncomplicated cellulitis (6)

Keep the area CLEAN
If there is a break in the skin -> protect the area
Saline compress: COLD or WARM, up to patient (evidence for both)
Analgesics
Elevation
Compression (only if elevation is not an option)

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What is the problem with giving NSAIDs in cellulitis

Speeds up healing of inflammation HOWEVER may also increase risk of GAS

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What do trials say about using compression stockings in cellulitis

Showed reduction in:
- pain
- tenderness
- edema
- hospitalization

May temporarily worsen symptoms by adding pressure, needs to be sized properly to prevent ulcers

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Is topical therapy effective for cellulitis?

ALWAYS NO - They won’t penetrate deep enough for cellulitis
Could also cause contact dermatitis -> worsen skin symptoms

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When is it absolutely necessary to give IV (4)

NPO
Ongoing vomiting
Unreliable absorption (incl. sepsis-induced hypotension)
Maybe acute severe sepsis

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What agents have excellent oral bioavailability and should almost always be given orally (9)

Clindamycin
Metronidazole
Doxycycline
TMP-SMX
Linezolid
FQs (not azith but still give orally)

Amoxicillin
Cephalexin
Cefadroxil

What agents have terrible oral bioavailability and should always be given parentally

Carbapenems
Vancomycin
Aminoglycosides
Penicillin G

When would we likely need IV formulation in moderate cellulitis (systemic signs, 38+ fever) (3)

Obesity
Severe edema (too large Vol of distribution)
Bacteremia (need enough drug in the bloodstream)

What are the harms of giving IV antimicrobials in cellulitis (2) and in general (2)

In cellulitis, associated fluid can exacerbate edema
In cellulitis, use of IV often leads to unnecessarily broad therapy for convenience of dosing (eg. ceftriaxone)

More ADRs
Risk for bloodstream infections

What are 2 things to look out for when giving oral treatment to an outpatient which might require IV (3)

Morbid obesity (BMI 40+) Very high edema Sick enough to require ICU, consider if hospitilized

When would you transition to oral therapy in hospital when IV is started? (2)

After evidence of improvement AND blood cultures, If done, are negative (72hrs)

When would we need to consider MSSA in cellulitis (3)

Purulence Penetrating trauma ICU

Which drugs are NOT effective for cellulitis? (3)

Aminoglycosides Metronidazole Nitrofuratnoin, Fosfomycin (only cover uropathogens)

Which abx has to be given in an empty stomach? (2)

Penicillin Cloxacillin

Which abx is only given IV? (3)

Pipercillin + tazo Carbapenems Vancomycin

Which abx in nephrotoxic

Vancomycin

Which abx has thrombocytopenia as a side effect if used longer than 14 days?

Linezolid

Which of the following abx causes hyperkalemia

Septra

Which abx has the least evidence in cellulitis

Doxycycline

Which abx has over 10% resistance in cellulitis

Macrolides (azithryomycin, clarithryomycin) Fluroquinolones (levofloxacin, moxiflocacin, clarithromycin)

Which abx can cause c diff

Clindamycin Fluroquinolones (levofloxacin, moxiflocacin, clarithromycin)

What is outpatient first line for cellulitis

Amoxicillin Penicillin Cloxacillin Cephalexin (1st gen) cefadroxil (1st gen) Septra

What is first line for inpatient who requires IV

Cefazolin (no septra due to large dilution requirement, will increase fluid)

What abx would you recommend if they have delayed HSR (type 4) to beta-lactam

IV Clindamycin

What are reasons where MSSA needs to be covered

1. Penetrating trauma 2. ICU (infection bad enough) 3. Purulence

If MSSA is suspected what drugs CAN'T we use? (3) (unsure)

Penicillin Amp/Amoxicillin (no BLI) Piperacillin

What are risk factors for MRSA? (4) Consider when?

- Crowded living conditions (prison, homeless, indigenous reserve) OR - Recent hospitalization - Recent travel (longer trips, trips to USA) - IV drug user Consider: (only consider if MSSA criteria is ALSO met)

What drugs are used if MRSA suspected?

ORAL Septra, doxycycline IV Vancomycin

What to monitor for cellulitis therapy () Dermatological (3) Systemic (1)

Dermatological sx: - Redness: to worsen + spread in first 24 hours (with effective antibiotic - as bacteria is releasing toxins when it dies) - Intensity of redness goes down BEFORE spread stops - Inflammation: can continue to spread for ≤72 hours Systemic sx: - fever up to 72 hours (usually at least 48 hours)

What is considered treatment failure in cellulitis (2) How do you assess?

- Inflammation spreading for >72 hours (assess by marking the borders before treatment) - New or worsening systemic sx after 24 hours

What does classic escalation of therapy on day 3 mean?

Very common for therapies to get escalated on Day 3. This is unnecessary, as it's likely because OT/PT made patient walk around after improvement.

What is usually the duration of therapy

5-7 days - excluding bacteremia or extensive disease

T/F Clinical endpoint is resolution of erythema

False - return to normal can take weeks or months

What to do upon treatment failure (3)

1. Check for deeper infection (fascia/muscle/bone) 2. Re-evaluate likely pathogens: consider VRSA, microbiological modifier (animal bite, rock climbing, etc…) Consider alternative diagnosis

How do we prevent recurrences of cellulitis? (4)

- Moisturize: prevent dryness/cracking - But avoid excessive moisture - Look out for Tinea Pedis (Athlete's foot): (microbreaks in the skin could be allowing bugs to be let in) - Treat lymphedema and chronic venous insufficiency (Elevation, reduce Sodium intake, Compression stockings)

When is chronic prophylaxis needed? Treatment Options (3) How often to reassess?

Needed when: - Recurrent infection (2 in 6 months or 3 in 12 months) When to consider: - only after implementing other risk reduction strategies What to use: * PO: Penicillin V or erythromycin BID * IM: Benzathine Penicillin Q15D Reassess appropriateness: annually

Which drugs are low risk for c. diff (3)

- Septra - macrolides - doxycycline - aminoglycosides