This was a fun article that searched the literature and dispensed with 10 myths about cellulitis.
Why does this matter?
Admissions for cellulitis have a huge economic impact and use valuable bed space in the hospital. And it is often misdiagnosed. Accurate diagnosis may reduce admissions and improve antibiotic stewardship.
Man, that looks red!
Myth 1 - Red = cellulitis
- Stasis dermatitis, DVT, gout, allergic reactions, and other skin conditions are also red.
- Elevation of the limb 45 degrees for 2 minutes will often make redness fade in most non-infectious causes, but redness will remain in cellulitis.
Myth 2 - My patient has bilateral leg cellulitis.
- This is exceedingly rare. There would have to be simultaneous inoculation of both legs.
- It's probably stasis dermatitis or something else.
Myth 3 - All skin infections need antibiotics.
- Very small abscesses may not need antibiotics. (But see this NEJM paper we will cover later this month...)
- Small areas of erythema, < 5 cm, may also not need antibiotics, especially if no systemic signs and not diabetic or immunocompromised.
Myth 4 - All skin infections need MRSA coverage.
- Skin infection confirmed to not have an abscess does not benefit from adding TMP/SMX to cephalexin.
- Furuncles should have MRSA coverage.
- Consider your local infection patterns and the patient's risk for MRSA.
Myth 5 - Admissions for cellulitis need MRSA coverage.
- See Myth 4 discussion.
- If patients are systemically ill, an antibiotic with MRSA coverage is not a bad idea.
Myth 6 - Clindamycin will cover MRSA.
- It depends on local resistance patterns at your facility. Resistance may be as high as 35% in some areas.
- Most MRSA strains remain sensitive to TMP/SMX and doxycycline.
Myth 7 - One also needs to add coverage for gram-negatives and anaerobes. Maybe, but only if:
- "Intensive care unit (ICU) level of care
- Concern for bloodstream or necrotizing infection
- Peri-rectal involvement, peri-orbital involvement, human or animal bite, surgical wound infection, traumatic aquatic injury, or osteomyelitis
- Chronic diabetic foot wounds
- Intravenous illicit drug use
- Presence of neutropenia or severe cell-mediated immunodeficiency
Myth 8 - If redness goes beyond the margin previously traced out, it is getting worse.
- This may be true, but in the first 48 hours, infection may spread a little while on antibiotics.
- Spreading redness and fever should be considered a treatment failure if beyond 48 hours on antibiotics.
Myth 9 - Repeat infection will not happen in patients taking antibiotic prophylaxis.
- Not true.
- If skin is cracked, fungal infection is present, or chronic edema remains, infection may still recur.
Myth 10 - Redness around tick bites indicates cellulitis.
- This is most often an inflammatory response to the bite.
- Be wary of erythema migrans in Lyme-endemic areas.
Top 10 Myths Regarding the Diagnosis and Treatment of Cellulitis. J Emerg Med. 2017 Jul 3. pii: S0736-4679(17)30436-5. doi: 10.1016/j.jemermed.2017.05.007. [Epub ahead of print]
Don't miss this core knowledge post on emDocs, Cellulitis Mimics.
Peer reviewed by Thomas Davis, MD.