Skin and soft tissue infection

Question 1

Cellulitis and erysipelas are described as acute spreading inflammation of the dermis and subcutaneous tissues with prominent ______ involvement

Answer 1

Lymphatic

Question 2

Which has a well-demarcated and raised border- cellulitis or erysipelas?

Answer 2

Erysipelas

Question 3

What is the best way to treat lymphedema associated with cellulitis

Answer 3

Elevation

Question 4

List three pathophysiologic components of cellulitis

Answer 4

Portal of entry
Lymphedema
Causative agent

Question 5

List some common portals of entry

Answer 5

Tinea pedis
Diabetic foot ulcer
Trauma
Eczema
Psoriasis
May have none evident

Question 6

List some causes of chronic lymphedema

Answer 6

Venous insufficiency (due to morbid obesity, heart failure, kidney disease)
Prior surgery- ex vein harvest, node dissection
Prior radiotherapy
Prior DVT
PREVIOUS CELLULITIS

Question 7

Erysipelas is commonly caused by _________. Non-purulent cellulitis is commonly caused by _____. Purulent cellulitis is commonly caused by _________

Answer 7

Erysipelas: Group A Strep
Non-purulent cellulitis: Group A Strep
Purulent cellulitis: S. aureus

Question 8

What distinguishes purulent from non-purulent cellulitis?

Answer 8

Presence of draining furuncle, carbuncle, boil, abscess

Purulent cellulitis caused mostly by S. aureus, commonly MRSA

Question 9

Describe why thorough history/ epidemiology is important in making a diagnosis of cellulitis

Answer 9

Can give insight into abnormal/ atypical microbial causes.

Ex animal bites- Pasteurella, salt water- Vibrio vulnificus

Question 10

List some risk factors for CA-MRSA

Answer 10

History of MRSA colonization
History of recurrent skin disease
SSTI with poor response to beta lactams
History of crowded living conditions, contact sports, MSM, IDU, shaving
Native American, Pacific Islander, Alaskan Natives

Question 11

Describe some ways to make a microbial diagnosis in cases of cellulitis

Answer 11

Blood cultures if hospitalized (low yield)
Needle aspiration from fluctuant areas or bullae (still only 25% yield)
ASO titer for GAS
MRSA swabs from nares, groin, axilla- still false negatives and positives

Question 12

Describe components of management of cellulitis

Answer 12

Look for unusual bacteria
Find and treat portal of entry
Manage lymphedema
Use antibiotics based on expected organism

Question 13

List antibiotics used in purulent cellulitis

Answer 13

MRSA/MSSA

doxycycline, minocycline, clindamycin, linezolid, vancomycin, daptomycin, ceftaroline

Question 14

List antibiotics used in non-purulent cellulitis

Answer 14

Group A Strep

penicillin, amoxicillin, dicloxacillin, cephalexin, clindamyin, nafcillin, ceftazolin, vancomycin

Question 15

Describe management of recurrent cellulitis

Answer 15

Portal of entry management
Lymphedema management
Low dose antibiotic prophylaxis

Question 16

True or false: treatment for necrotizing fasciitis is IV antibiotics

Answer 16

False, antibiotics alone are not sufficient.

Need early and aggressive surgical debridement

Question 17

List clinical clues that suggest life threatening necrotizing SSTI

Answer 17

Pain out of proportion to what is seen
Systemic toxicity- abnormal kidney/liver tests, anion gap, TSS, shock
Rapid progression
Necrosis
Anesthesia- indicates infarction of nerve supply

Question 18

List risk factors for necrotizing SSTI

Answer 18

Trauma
Surgical wound
Peripheral vascular disease
Diabetes
Obesity
Alcohol abuse, IDU
Immunocompromised

Question 19

Acute diabetic foot infections are commonly caused by

Answer 19

S. aureus, streptococci

Question 20

Chronic neuropathic diabetic foot ulcers are typically _________

Answer 20

polymicrobial
S. aureus, Coagulase-negative Staph, enterococci, GBS, Gram neg aerobes, anaerobes
Require broad spectrum antibiotics

Question 21

For all chronic diabetic foot ulcers, clinicians should be concerned about/ look for signs of _____

Answer 21

osteomyelitis

Question 22

Neutropenic hosts are more likely to have SSTI caused by ___

Answer 22

Aerobic GNR + staph/strep (fungi later)
Always include potent anti-pseudomonal coverage
Ecthyma gangrenosum- Pseudomonas skin infection seen in neutropenic hosts

Question 23

CMI impaired hosts are more likely to have SSTI caused by ______

Answer 23

mycobacteria, Nocardia, cryptococcus, histoplasmosis, other fungi, VZV, HSV, CMV, scabies