RX513 Skin and Soft Tissue Infections

What are the types of purulent SSTIs?

- Abscess

- Furuncle

- Carbuncle

What are the types of non-purulent SSTIs?

- Cellulitis

- Erysipelas

When are blood cultures indicated for SSTIs?

- Severe infections

- IV drug use

What is given for a necrotizing SSTI?

CT scan

Cutaneous abscesses

Collection of pus within the dermis and deeper skin tissue

Folliculitis

Infection only of the hair follicle

Furuncle

AKA "boil", infections of the hair follicle involving a small abscess

Carbuncle

Infections involving several adjacent hair follicles

How do purulent SSTIs present?

- Tender, red nodule(s)

- Erythema

- Systemic signs (carbuncles and abscesses only, moderate)

What pathogens cause purulent SSTIs?

- MRSA

- Pseudomonas aeruginosa in whirlpools/hot tubs

When is an SSTI classified as severe?

- Failed incision & drainage and PO antibiotics

- Immunocompromised

- SIRS

- Deeper/necrotizing infection

What are the SIRS criteria for a severe SSTI?

- Temperature > 38*C

- Temperature < 36*C

- HR > 90 bpm

- RR > 24 bpm

- WBC > 12K

- WBC < 4K

What is the duration of therapy for a purulent or non-purulent SSTI?

5 days

What are the key points of non-purulent SSTIs?

- Involves epidermis and dermis

- Progresses to SUBQ fat

- With or without involvement of fascia

- History of wound from minor trauma

- Risk factors are obesity, diabetes, injection drug use, pre-existing SSTI

What are the characteristics of non-purulent SSTIs?

- Fever, chills, malaise

- Hot and painful to touch

- Systemic symptoms

- Non-elevated with poorly defined margins (orange peel)

- Involvement of regional lymphatic system

What pathogens cause non-purulent SSTIs?

- Group A Strep (also B, C, F, and G)

- Staphylococcus aureus

When is MRSA coverage used in a non-purulent SSTI?

- Penetrating trauma

- IV drug use

- Purulent drainage

- MRSA infection elsewhere

What are the key points of necrotizing SSTIs?

- Medical emergencies

- Require aggressive surgical intervention/antibiotics

- Involve all skin structures

How do necrotizing SSTIs present?

- Marked systemic toxicity

- Change in skin color to maroon/purple/black

- Bullae (large blisters)

- Crepitus (soft tissue gas)

- Cutaneous anesthesia

- Edema beyond margins of erythema

What are the pathogens that cause necrotizing SSTIs?

- Group A Strep

- MRSA

- Clostridium perfringens (gas gangrene)

- Gram-negative bacilli (Vibrio vulnificus, Aeromonas hydrophila)

- Other anaerobes (Peptostreptococcus)

What are the treatment components for necrotizing SSTIs?

- ESBL (piperacillin/tazobactam, cefepime, carbapenem)

- Clindamycin

- Vancomycin

What is the purpose of clindamycin in a necrotizing SSTI?

- Efficacy is not affected by large bacterial burden

- Not affected by bacterial growth phase

- Inhibits Streptococcal toxin production

What are the key points of osteomyelitis?

- Involvement of the bone

- Treatment duration is 4-6 weeks

What are the treatment options for traditional osteomyelitis patients?

- Ceftriaxone

- Cefazolin

- Vancomycin or doxycycline

What are the treatment options for osteomyelitis patients with IV drug use?

- Ciprofloxacin

- Anti-Pseudomonal beta-lactam

- Add vancomycin or daptomycin

What are the treatment options for osteomyelitis patients with trauma/post-operative?

- Anti-Pseudomonal beta-lactam

- Add vancomycin or daptomycin

What are the traditional symptoms of diabetic foot infections?

- Erythema/warmth/swelling

- Induration (hardening of soft tissue)

- Tenderness/pain

- Purulent secretions

What pathogens commonly cause infected, antibiotic-naive diabetic foot ulcers?

- Staphylococcus aureus

- Group Streptococci

What pathogens commonly cause chronic infected diabetic foot ulcers after antibiotic exposure?

- Staphylococcus aureus

- Group Streptocci

- Enterobacteriaceae

- Obligate anaerobes

What pathogens commonly cause macerated diabetic foot ulcers?

- Pseudomonas aeruginosa

- Aerobic Gram-positives

What pathogens commonly cause chronic, non-healing diabetic foot ulcers with a history of broad-spectrum antibiotic therapy, and/or severe infections?

- Aerobic Gram-positives

- Enterobacteriaceae

- Pseudomonas aeruginosa

- Obligate anaerobes

What are the MRSA risk factors for a diabetic foot infection?

- History of MRSA infection or colonization in past year

- Recent hospitalization or antibiotic use

What are the Pseudomonas risk factors for a diabetic foot infection?

- Warm climate/water exposure

- Failed non-Pseudomonal antibiotics

Duration of therapy for standard diabetic foot infection.

1-2 weeks

Duration of therapy for diabetic foot infection that is:

- Responding slower than expected

- Improving but extensive infection

- Severe peripheral artery disease

- Moderate to severe disease

3-4 weeks

Duration of therapy for moderate/severe diabetic foot infection following surgical debridement.

10 days

Duration of therapy for diabetic foot infection involving bone (osteomyelitis)?

3-6 weeks

Duration of therapy for diabetic foot infection involving bone (osteomyelitis) following amputation?

1-2 days

Duration of therapy for diabetic foot infection involving bone (osteomyelitis) following debridement of infection from bone?

1-2 weeks

Diabetic foot infection:

- Erythema > 0.5 but < 2 cm around the wound

- No systemic manifestations

- No bone involvement

Mild

Diabetic foot infection:

- Erythema > 2 cm around the wound

- Involvement of skin structures deeper than SUBQ

- No systemic manifestations

- No bone involvement

Moderate

Diabetic foot infection:

- Erythema of any size

- Involvement of any skin structures

- SIRS positive (2 criteria met)

- Bone involvement present

Severe

What is the standard therapy for a mild diabetic foot infection?

- Dicloxacillin

- Cephalexin

- Levofloxacin, moxifloxacin, doxycycline, or sulfamethoxazole/trimethoprim if allergic

What should be swapped for a mild diabetic foot infection with recent antibiotic use (last 30 days)?

- Amoxicillin/clavulanate

- Levofloxacin or moxifloxacin

- Sulfamethoxazole/trimethoprim

What should be swapped for a mild diabetic foot infection with MRSA risk factors?

- Sulfamethoxazole/trimethoprim

- Doxycycline

- Linezolid

What is the standard therapy for a moderate or severe diabetic foot infection (start IV for severe)?

- Ampicillin/sulbactam

- Ceftriaxone

- Amoxicillin/clavulanate

- Cefuroxime

What should be swapped for a moderate or severe diabetic foot infection with recent antibiotic use (last 30 days)?

- Piperacillin/tazobactam

- Ceftriaxone

- Ertapenem

- Cefuroxime

What should be swapped for a moderate or severe diabetic foot infection with ischemic/necrotic limb?

- Ampicillin/sulbactam

- Ceftriaxone + metronidazole

- Amoxicillin/clavulanate

- Cefuroxime + metronidazole

What should be swapped for a moderate or severe diabetic foot infection with macerated ulcer or warm climate?

- Piperacillin/tazobactam

- Meropenem

- Imipenem

- Dicloxacillin + ciprofloxacin

What should be added for a moderate or severe diabetic foot infection with MRSA risk factors?

- Vancomycin

- Daptomycin

- Linezolid

- Sulfamethoxazole/trimethoprim

- Doxycycline

What are the key points of impetigo?

- Superficial skin infection

- Highly contagious

- Common during hot, humid weather

- Causes pruritis

- Caused by Staphylococcus aureus and beta-hemolytic Streptococcus

What is used for mild impetigo without facial lesions?

Mupirocin for 5 days

What is used empirically for impetigo with face or multiple lesions?

- Dicloxacillin for 7 days

- Cephalexin for 7 days

What are the options for impetigo in patients allergic to penicillins?

- Doxycycline

- Clindamycin

- Sulfamethoxazole/trimethoprim

What is the most common pathogen in dog bites?

Pasturella spp.

What is the most common pathogen in cat bites?

Pasturella multocida

What is the most common pathogen in human bites?

Eikenella corrodens

What are the first-line treatment options for bites?

- Amoxicillin/clavulanate

- Cefuroxime + clindamycin

How long is antibiotic therapy given for bites?

7-14 days

What is used for bites in patients allergic to penicillins?

- Sulfamethoxazole/trimethoprim + clindamycin

- Ciprofloxacin + clindamycin

- Doxycycline + clindamycin

When should preemptive therapy be given for bites (3-5 days)?

- Immunocompromised/asplenic

- Advanced liver disease

- Pre-existing or resultant edema

- Moderate-to-severe bites

- Bites involving hand, face, or joints

What are the treatment options for a moderate purulent SSTI?

- Sulfamethoxazole/trimethoprim (empric, MRSA)

- Doxycycline

- Dicloxacillin or cephalexin (MSSA)

What are the treatment options for a severe purulent SSTI?

- Vancomycin

- Daptomycin

- Linezolid

- Telavancin

- Ceftaroline

- Nafcillin, cefazolin, or clindamycin (MSSA)

What are the treatment options for a mild non-purulent SSTI?

- Penicillin VK

- Cephalosporin

- Dicloxacillin

- Clindamycin

What are the treatment options for a moderate non-purulent SSTI (IV)?

- Penicillin

- Ceftriaxone

- Cefazolin

- Clindamycin

What is the empiric treatment option for a severe non-purulent SSTI?

Vancomycin + piperacillin/tazobactam

First-line therapy for a mild purulent infection is:

Incision and drainage

A patient with a mild DM foot infection with MRSA risk factors (history of MRSA) should be treated with:

Doxycycline

Treatment for a severe DM foot infection in a patient with recent antibiotics is:

Piperacillin/tazobactam

Treatment for a moderate DM foot infection with only MRSA risk factors is:

Ceftriaxone + vancomycin

Treatment for a mild non-purulent infection is:

Penicillin VK

What is the best regimen for a moderate DM foot infection in a patient that lives in a wet climate and has no other risk factors?

Dicloxacillin + ciprofloxacin

What is the best treatment for a patient with a cat bite to their face (no signs of infection)?

Amoxicillin/clavulanate

The best option for a moderate purulent infection is:

Sulfamethoxazole/trimethoprim

Which of the following factors is a reason to preemptively prescribe antibiotics in a patient with a dog bite?

Bite that penetrated the joint

Treatment of mild impetigo on the hand in a patient without drug allergies is:

Mupirocin

A mild DM foot infection with recent antibiotics and MRSA risk factors should be treated with:

Sulfamethoxazole/trimethoprim

First line therapy for moderate non-purulent infections with an allergy to penicillin (anaphylaxis) is:

Clindamycin

Which of the following should be started if there is a concern for a necrotizing infection?

A. Piperacillin/tazobactam

B. Clindamycin

C. Ceftriaxone

D. Vancomycin

A, B, and D

Treatment for a moderate non-purulent infection is:

Ceftriaxone

Treatment for a mild DM foot infection without any risk factors or allergies is:

Cephalexin

First-line therapy for a patient with a severe purulent infection is:

Vancomycin

88-year-old male with hypothyroidism and atrial fibrillation with a human bite to the thigh without signs of infection

No antibiotics

21-year-old male that was in a bar fight and has lesions on his right knuckles without signs of infection

3 days of antibiotics

8-year-old, otherwise healthy female with a cat bite to the calf, without signs of infection

No antibiotics

75-year-old female with lung cancer undergoing chemotherapy with a dog bite to the forearm without signs of infection

3 days of antibiotics

54-year-old male with hypertension with a dog bite to the thigh that is erythematous

7 days of antibiotics

25-year-old, otherwise healthy female with a cat bite on her wrist with pus and redness around the puncture site

7 days of antibiotics

Use the following case to answer the question:

This is a 85-year-old male with a history of diabetes (A1C of 8.5%), HTN, hyperlipidemia, CAD and BPH. He has not had an ulcer before on the left side, but has had his right little toe amputated 3 years prior. Patient presents to the outpatient clinic with a new left lower ulcer on his big toe.

Physical Exam:

Allergies: none

Vitals: temp 98.2, HR 82, RR 18, BP 156/94

Wt: 89 kg, Ht: 178 cm

Antibiotic

Amoxicillin/clavulanate

Use the following case to answer the question:

This is a 85-year-old male with a history of diabetes (A1C of 8.5%), HTN, hyperlipidemia, CAD and BPH. He has not had an ulcer before on the left side, but has had his right little toe amputated 3 years prior. Patient presents to the outpatient clinic with a new left lower ulcer on his big toe.

Physical Exam:

Allergies: none

Vitals: temp 98.2, HR 82, RR 18, BP 156/94

Wt: 89 kg, Ht: 178 cm

Duration of therapy

1 week

Use the following case to answer the question:

This is a 43-year-old male with a history of IVDU (meth/heroin/marijuana) last use 1 week ago, tobacco abuse and MRSA. He reports a hx of recurrent MRSA infections, last requiring admit to OSH 4/2020. Patient presents to the outpatient clinic with a new right upper extremity abscess. No n/v/d or rashes. Has several excoriations/picked lesions over BUE and BLE.

Physical Exam:

· Skin: Skin warm and dry. Multiple excoriations/lesions over BUE and BLE from picking. There is a 4x4 cm open lesion on right upper extremity on the forearm with surrounding tenderness. No active drainage, but positive for fluctuance and induration.

Allergies: PCN (hives)

Vitals: temp 98.6, HR 75, RR 16, BP 146/92

Wt: 102 kg, Ht: 185 cm

Labs: WBC 11.4, SCr 0.7

Antibiotic

Sulfamethoxazole/trimethoprim

Use the following case to answer the question:

This is a 43-year-old male with a history of IVDU (meth/heroin/marijuana) last use 1 week ago, tobacco abuse and MRSA. He reports a hx of recurrent MRSA infections, last requiring admit to OSH 4/2020. Patient presents to the outpatient clinic with a new right upper extremity abscess. No n/v/d or rashes. Has several excoriations/picked lesions over BUE and BLE.

Physical Exam:

· Skin: Skin warm and dry. Multiple excoriations/lesions over BUE and BLE from picking. There is a 4x4 cm open lesion on right upper extremity on the forearm with surrounding tenderness. No active drainage, but positive for fluctuance and induration.

Allergies: PCN (hives)

Vitals: temp 98.6, HR 75, RR 16, BP 146/92

Wt: 102 kg, Ht: 185 cm

Labs: WBC 11.4, SCr 0.7

Duration of treatment

5 days