Skin and Soft Tissue Infections (3-1-22)

Question 1

What bacteria is the most common cause of skin and soft tissue infections?

Answer 1

Most common

1. ) Beta-hemolytic streptococci
2. ) Coagulase negative staphylococcus aureus

Question 2

Why is staph and strep the most common bacteria that cause skin and soft tissue infections?

Answer 2

Because on the normal skin flora are staph and strep. Thus, if you have any cut in the skin, these bacteria can get deeper into the skin and cause an infection

Question 3

Why is it important to get a history for pts with skin and soft tissue infections?

Answer 3

B/c this way you can figure out what the bacteriology of the SSTI is and the patient risk

Question 4

What is impetigo? On what body part do you usually see it?

Answer 4

Superficial skin infection of the epidermis consisting of papules when ruptures, form a dried honey colored crust

See on skin of face and extremities

Question 5

Impetigo symptoms?

Answer 5

Have bullous that rupture and leave a sometime itchy or painful honey colored crust.

Non bullous is more common than bullous

Question 6

What organisms are more likely to cause non-bullous or bullous impetigo?

Answer 6

Non-bullous –> Group A strep or MSSA

Bullous –> MSSA

Question 7

How does impetigo happen? Pathogenesis

Answer 7

If there is a cut or abrasion, an organism can directly invade healthy skin or get into the superficial layers of the skin

Question 8

Which is more contagious, impetigo bullous or non-bullous?

Answer 8

non-bullous

Question 9

What patients are at the highest risk of getting impetigo?

Answer 9

1. ) CHILDREN
2. ) have skin trauma
3. ) hot/humid clincates
4. ) poor hygiene
5. ) day care settings
6. ) crowding
7. ) malnutrition
8. ) diabetes

make sense why children are at high risk

Question 10

What are the organisms that cause Impetigo?

Answer 10

1.) Staph aureus
AND/OR
2.) Strep pyogenes (group A streptococcus)

Question 11

How do you know if you have impetigo?

Answer 11

Look at clinical presentation: Have a honey colored crust discharge

Question 12

How can you treat impetigo if mild?

Answer 12

Give topical mupirocin 2% or retapamulin 1% ointment BID x 5 days

can also resolve spontaneously

Question 13

How can you treat more “severe” impetigo? (want to prevent new vesicle formation, decrease transmission, transitioned to crusted phase)

Answer 13

Systemic PO antibiotics:

1. ) Dicloxacillin (1st line)
2. ) Cephalexin
3. ) Erythromycin
4. ) Clindamycin
5. ) Amoxicillin/clavulanate

if have beta lactam allergy can go to erythromycin or clindamycin

Question 14

What is cellulitis?

Answer 14

Acute spreading infection that involves the epidermis, dermis, and SQ tissue without fascial involvement –> thus can reach bloodstream –> so get systemic SE

outpatient or inpatient

Question 15

Where do you most often see cellulitis ?

Answer 15

Lower extremities –> only one one extremity not both

but depending on risk factors or where disruption of skin is, you can see it anywhere

Question 16

Symptoms of cellulitis?

Answer 16

Rapid spreading of redness, tenderness, warmth, and swelling in skin with POORLY DEFINIED border

Fever, malaise, leukocytosis

Question 17

How does one get cellulitis?

Answer 17

Due to trauma, wounds, Athlete’s feet, dry/crack skin, injection drug use, ulcers, or surgery, the organisms can get in through there

Question 18

Patients at risk of cellulitis?

Answer 18

1. ) normal hosts (anyone)
2. ) diabetes –> b/c of neuropathy, vascular changes, dry/cracked skin
3. ) injection drug users
4. ) pts with arterial or venous insufficiency
5. ) obese pts
6. ) pts with lymphedema
7. ) immunocompromised pts

Question 19

What is erysipelas

Answer 19

A type of cellulitis caused by B-hemolytic streptococci involving only the upper dermis and superficial lymphatics with intense erythema and CLEARLY defined border. Also has the peau d’ orange

Question 20

What are the unique symptoms of erysiplas?

Answer 20

Clearly defined borders and the peau d’ orange (orange peel) appearance due to edema surround the hair follicles

Question 21

Where is erysipelas mostly seen on body?

Answer 21

FACE

Question 22

What are the common bacteria causes of cellulitis?

Answer 22

1. ) beta hemolytic strep (s. pyogenes)
2. ) Staph aureus (including MSSA)

For injection drug users also included MRSA

Question 23

When would you suspect MRSA with Cellulitis?

Answer 23

• Injection drug users
• penetrating trauma
• evidence of MRSA infection else where
• Purulent cellulitis (abscess)
• SIRS

Question 24

Empiric treatment for Mild diabetic foot infection?

Answer 24

• Cephalexin PO
• Dicloxacillin PO
• Amoxicillin/clavulanate PO

If MRSA suscepted:
- Clindamycin or Bactrim PO

Question 25

What is the likely causative organisms for mild diabetic foot infection?

Answer 25

• Beta-hemolytic strep
• Staph aureus

Possible for MRSA as well (if previously MRSA infection/colonization, or if local prevalence of MRSA is high)

Question 26

What are the likely causative organisms for moderate diabetic foot infection?

Answer 26

• Beta-hemolytic Strepococcus
• Staphylococcus aureus (MSSA or MRSA if have risk factors)
• Consider enterobacteriaceae if they have been on an antibiotic in past 30 days
• Consider obligate anaerobes if they have a necrotic wound that has not been debrided

Question 27

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

Answer 27

• If have high local prevalence of MRSA
• Prior history of MRSA infection/colonization
• Severe infection

Question 28

What is the empiric treatment for moderate DFI?

Answer 28

• IV cefazolin (or vancomycin if have suspected MRSA)
• IV ceftriaxone alone if suspected enterobacteriaceae
• Add PO metronidazole if anaerobes are suspected

Question 29

What are the common causative organisms for severe diabetic foot infection?

Answer 29

• Beta-hemolytic strep
• staph aureus (MSSA and MRSA)
• Enterobacteriaceae
• Pseudo. aeruginosa
• Anaerobes

Question 30

What are empiric therapy options for severe diabetic foot infection?

Answer 30

Vancomycin

PLUS

Zosyn or meropenem
OR
Ceftazidime or cefepime + PO metronidazole
OR
Levofloxacin or ciprofloxacin + PO metronidazole

Question 31

What is the treatment for empiric necrtizing fascilitis?

Answer 31

1. ) need to do surgery to remove debrided necrotic wound
2. ) Vanc + meropenem OR vanc + zosyn
3. ) Add clindamycin

Need to do in this order

Question 32

What is targeted therapy for necrotizing fascilitis?

Answer 32

Strep pyogenes –> penicillin
Staph aureus –> nafacillin or oxacillin (MSSA)
MRSA –> vancomycin

Question 33

Where does necrotizing fascilits affect? Layers?

Answer 33

Lower extremities, lower abdomen, genital area

Fascia and SC muscle/fat

Question 34

How do you know if you have DFI?

Answer 34

Must have 2 or more of following:

• Swelling/induration
• Erythema
• warmth
• Pain
• Tenderness
• Purulent discharge

Systemic signs (fever, tachycardia, leukocytosis)

Question 35

What is conisdered as mild DFI?

Answer 35

1.) cellulitis extends < 2 cm from border of ulcer. Has NO SIRS

Usually limited to superficial tissue

Question 36

What is considered as moderate DFI?

Answer 36

Cellulitis extends >2 cm from border of ulcer

OR

Involves deeper tissue such as (abscess, septic arthritis, osteomyelitis, fasciitis, cellulitis)

WITHOUT SIRS

Question 37

What is considered as severe DFI?

Answer 37

Local infection with signs of 2 or more of SIRS:

1. ) Temp > 38 C
2. ) HR > 90
3. ) RR > 20
4. ) WBC > 12,000
5. ) Bands > 10%