Cellulitis

Question 1

What are SSTIs?

Answer 1

skin and soft tissue infections

Question 2

How are SSTIs divided?

Answer 2

purulent (pus): bullous impetigo, carbuncles, cutaneous abscess, folliculitis, purulent cellulitis
non-purulent (no pus): non-bullous impetigo, non-purulent cellulitis

Question 3

Which tissues does cellulitis hit?

Answer 3

initially affects epidermis and dermis
may spread within superficial fascia
may spread through lymphatic tissue and bloodstream

Question 4

What are the symptoms of cellulitis?

Answer 4

affected area is hot and painful
erythema
inflammation (edema) with little or no necrosis or suppuration of soft tissue
may be associated with purulent drainage, exudates and/or abscess
tender lymphadenopathy
fever, chills, malaise

Question 5

What do people with cellulitis often have a history of?

Answer 5

antecedent minor trauma
abrasion
ulcer
surgery

Question 6

Which areas of the body are commonly hit by cellulitis?

Answer 6

hands
feet
lower legs (differ from venous stasis; bilateral, not hot)
peri-orbital (more common in kids, H. influenzae)

Question 7

True or false: cellulitis is typically bilateral

Answer 7

false
typically unilateral
bilateral should prompt consideration of other diagnoses

Question 8

What are the microorganisms that cause cellulitis?

Answer 8

group A strep
staph aureus
-MSSA: sensitive to cloxacillin
-MRSA: not susceptible to beta-lactam antibiotics
-CA-MRSA: onset in community without health-care associated
risk factors
-HCA-MRSA: health care associated MRSA

Question 9

Which class of antibiotics should never be given for MRSA?

Answer 9

beta-lactams

Question 10

In terms of purulent vs non-purulent cellulitis, which organisms are more likely to cause each?

Answer 10

non-purulent: group A strep
purulent: S. aureus

Question 11

What are the risk factors for CA-MRSA?

Answer 11

5 C’s: crowding, frequent skin contact, compromised skin, sharing contaminated personal items, lack of cleanliness
age <2yrs and >65yrs
athletes of contact sports
men who have sex with men
living in correctional facilities
history of colonization or recent infection with CA-MRSA
antibiotic use in last 6 months
recent invasive procedures
IV drug use
military personnel
homeless persons
prior hospitalization for SSTI
trauma associated

Question 12

When should you cover for MRSA?

Answer 12

patient from highly endemic area for CA-MRSA
CA-MRSA risk factors
lack of improvement on beta-lactams
clinical judgement (serious illness, immunocompromised)

Question 13

True or false: SSTIs often respond to therapy that does not cover CA-MRSA even if MRSA is endemic or cultured

Answer 13

true

Question 14

What are the distinguishable signs of CA-MRSA from other organisms?

Answer 14

no reliable signs

Question 15

What is the antibiotic choice for non-purulent cellulitis?

Answer 15

cephalexin

Question 16

What is the dosing of cephalexin for non-purulent cellulitis in adults?

Answer 16

500mg po QID

Question 17

What is the dosing of cephalexin for non-purulent cellulitis in pediatrics?

Answer 17

50-100mg/kg/d QID

Question 18

What is the susceptibility of GAS isolates in Saskatoon and Regina to cephalexin?

Answer 18

100%

Question 19

Which potentially causative organism of cellulitis will cephalexin not cover?

Answer 19

MRSA

Question 20

What are the antibiotic choices for penicillin allergic patients for non-purulent cellulitis?

Answer 20

clindamycin
erythromycin

Question 21

What is the dosing of clindamycin in adults for non-purulent cellulitis? What about kids?

Answer 21

adults: 300mg po QID or 450mg po TID
children: 20-40mg/kg/d po TID or QID

Question 22

What is the dosing of erythromycin in adults for non-purulent cellulitis? What about kids?

Answer 22

adults: 250mg po QID or 500mg po BID
kids: 30-40mg/kg/d po BID

Question 23

What are the choices of antibiotics for purulent cellulitis, assuming it is MSSA?

Answer 23

cephalexin (same doses)
cloxacillin

Question 24

What is the dosing of cephalexin in adults for purulent cellulitis? What about kids?

Answer 24

500mg po QID
50-100mg/kg/day QID

Question 25

What is the dosing of cloxacillin in adults for purulent cellulitis? What about kids?

Answer 25

adults: 500mg po QID
kids: 50mg/kg/d

Question 26

What are the antibiotic choices for purulent cellulitis if the causative organism is MRSA or the patient is allergic to penicillin?

Answer 26

SMX/TMP
doxycycline
clindamycin

Question 27

What is the dosing of SMX/TMP in adults for purulent cellulitis? What about kids?

Answer 27

adults: 1-2 DS tabs po BID
kids: 8-12mg/kg/d (TMP) po BID

Question 28

What is the dosing of doxycycline in adults for purulent cellulitis? What about kids?

Answer 28

adults: 100mg po BID
kids: 4mg/kg/d BID

Question 29

How old must a child be to receive doxycycline for purulent cellulitis?

Answer 29

9 years old
-CI under 8 years old

Question 30

What is the issue with prescribing clindamycin for purulent cellulitis?

Answer 30

resistance with MRSA

Question 31

What are the choices of empiric therapy for GAS and MRSA?

Answer 31

cephalexin plus SMX/TMP
OR cephalexin plus doxycycline
-requires two antibiotics because cephalexin covers GAS but
not MRSA
-SMX/TMP and doxycycline have poor coverage for GAS but
cover MRSA

Question 32

What is the duration of therapy for uncomplicated cellulitis?

Answer 32

5 days of therapy is as effective as 10 days providing there is clinical improvement by day 5

Question 33

What are important counselling points with cellulitis?

Answer 33

may worsen in first few days (part of healing process, not TX failure)
full skin healing may take 1-2 weeks after antibiotics are stopped

Question 34

What are non-pharmacologic therapies for cellulitis?

Answer 34

incision and drainage
-for abscess <5cm I&D alone is adequate; antibiotics do not
help heal the infection any faster
elevation of affected limb

Question 35

What is key to successful treatment of purulent skin infections?

Answer 35

incision and drainage