#246 Take a Bite out of Cellulitis with Dr Boghuma Titanji

December 14, 2020 | By Matthew Watto, MD

Master common skin and soft tissues infections: cellulitis, abscesses, human and animal bites with returning guest, infectious diseases expert, Dr Boghuma Titanji MD, PhD @boghuma (Emory; TED). 

Credits

• Written (including CME) and Produced by: Matthew Watto MD, FACP 
• Cover Art and Infographic by: Beth Garbitelli
• Hosts: Matthew Watto MD, FACP; Paul Williams MD, FACP   
• Editor: Matthew Watto (written materials); Clair Morgan of nodderly.com
• Guest: Boghuma Titanji MD, M.Sc., DTM&H, PhD

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Time Stamps*

*Note: Time Stamps refer to ad free version. 

• 00:00 Sponsor(s), Intro, disclaimer, guest bio
• 02:00 Picks of the Week
• 06:00 Definitions, Initial Approach to cellulitis
• 10:35 Nonpurulent cellulitis; antibiotic choice
18:10 Fish handler’s disease
• 24:30 Recurrent cellulitis
• 31:30 Purulent cellulitis and MRSA; Antibiotic choice; Step down therapy
• 47:33 Abscesses; Adjuvant antibiotics; Packing Wounds
• 53:30 Decolonization for recurrent MRSA infections
• 56:30 Human Bites (clenched fist injury); Dog bites and Cat bites
• 67:10 Take home points and Outro

Top Pearls – Cellulitis, Abscesses and Bites

1. Prescribe antibiotics for a time range (e.g. 5-7 days) and re-evaluate the patient to shorten or lengthen based on clinical response (expert opinion). 
2. Cefadroxil and cephalexin are 1st gen cephalosporins with near identical spectrums, but the former requires only twice daily dosing!
3. Consider adding anaerobic coverage if infection involves the genitals, axilla, perioral tissues or perineum (expert opinion).
4. Compressive therapy can help prevent recurrent lower extremity cellulitis. 
5. Send wound cultures if giving antibiotics for purulent infections.
6. Packing most wounds after I&D is optional. 

Dr. Titanji’s Take Home Points

When evaluating cellulitis or bites and choosing antibiotics (abx) consider these factors:

• Site of infection (Are anaerobes present in the area?)
• The host (Are they immunocompromised?)
• Mechanism of Injury
• Patient exposures (e.g. MRSA risk factors)
• Ability to adhere to an abx regimen (e.g. BID over QID dosing)
• Collateral damage to flora 

Cellulitis, Human Bites and Animal Bites Show Notes

Diagnosis of Cellulitis

Cellulitis = Redness, pain, swelling and warmth in the skin caused by an introduction of infection. Note: Misdiagnosis is common (Li, JAMA Dermatol 2018).

Think Staphylococcus if purulence is present. 

Erysipelas – superficial

Cellulitis – deeper infection into the dermis

Abscess – collection of purulence in the dermis

Nonpurulent cellulitis

Think Strep.

Oral options for Strep

(IDSA SSTI Guideline 2014)

• 1st generation cephalosporin (Note: cefadroxil only requires twice daily dosing)
• Penicillins (Dicloxacillin, Penicillin)
• Clindamycin
• Note: Despite the classic teaching that TMP-SMX does not reliably cover Strep, a recent RCT found no difference in efficacy for clindamycin vs TMP-SMX for uncomplicated cellulitis (regardless of the presence of purulence) —Talan, Clin Inf Dis 2016. 

Kashlak Pearl: Dr Titanji writes a time range (e.g. 5-7 day script) and schedules a re-evaluation during that time period to determine the need to extend the course of therapy (or stop early). 

Kashlak Pearl: Dr Titanji may be more aggressive with IV antibiotics based on location of the cellulitis (e.g. face) and immunocompromised status. She may add coverage for anaerobes if infection involves the genitals, axilla, perioral tissues or perineum.

Kashlak Pearl: Bilateral cellulitis is rare so consider an alternate explanation! E.g. pseudocellulitis

Recurrent Cellulitis

Look for underlying predisposing factors like venous stasis, obesity, or lymphedema. Also, ask yourself, “Is this really cellulitis or pseudocellulitis?”. Early consultation with dermatology can help identify pseudocellulitis (Li, JAMA Dermatol 2018). Common mimics include: stasis dermatitis, contact dermatitis, viral rash, trauma, and chronic wounds.

Prevention of recurrent cellulitis

Suppressive (prophylactic) antibiotics work, but they select for resistant organisms. Compressive therapy, in addition to patient education, recently proved effective for the prevention of recurrent cellulitis of the leg (Webb, NEJM 2020).

Cellulitis in a Fish Handler (Water Exposure)

Bacteria found in fish and water that may contribute to skin infection include Erysipelothrix rhusiopathiae, Aeromonas, and *Vibrio. *Be on high alert for severe infection if the patient has underlying liver disease or hemochromatosis.

Treatment for Erysipelothrix, Aeromonas = Fluoroquinolones

Treatment for Vibrio = Doxycycline 

Purulent Cellulitis

Think Staph aureus. 

MRSA risk factors include: HIV, on dialysis, long term resident in a facility, recent hospitalization or surgery (UpToDate accessed 12/5/20), military recruits, and those in gyms.

When to get Imaging and Blood Cultures

Dr Titanji notes imaging and blood cultures are more likely beneficial if over a bony prominence (expert opinion), near implanted hardware (expert opinion) or in patients who are immunocompromised, severely ill, or have animal bite wounds  (IDSA SSTI Guideline 2014).  Note: Imaging and blood cultures are not required or cost-effective for all-comers (Ko, JAMA Int Med 2018).  

Culture purulent exudates if present. Even finding MSSA is useful as it allows antibiotics to be narrowed.

Oral options for MSSA (targeted)

(IDSA SSTI Guideline 2014)

• Dicloxacillin
• Cephalosporins 

Oral options for MRSA

(IDSA SSTI Guideline 2014)

• Doxycycline
• TMP-SMX
• Clindamycin
• Linezolid (typically reserved for unique cases)

Kashlak Pearl: Limb elevation and offloading of the affected limb can improve recovery time. 

Kashlak Pearl: Remember to cover for anaerobes (w/either clinda or metronidazole) in areas where anaerobes are likely to be lurking e.g. perianal and perioral tissues, axilla, and groin (expert opinion).

Switching from IV to oral antibiotics

Transition to oral when clinical exam improves and vitals signs have normalized (expert opinion). 

Kashlak Pearl: In the hospital we often give vancomycin plus a cephalosporin. The latter agents have better bactericidal action, plus coverage for MSSA and Strep. Step down regimens from vancomycin should be tailored based on suspected organisms, convenience of dosing and tolerability of a regimen (expert opinion).

Abscesses

Antibiotics for the patient with abscess?

Dr Titanji’s rule of thumb: *Small abscesses under 2 cm typically don’t need antibiotics after incision & drainage (expert opinion). Be sure to follow up and ensure resolution. Caveats: Dr Titanji may prescribe antibiotics (short course) for patients who have diabetes or are immunocompromised as they might need an extra boost to help “mop up” the infection. 

For *large abscesses over 2 cm, Dr Titanji recommends antibiotics (typically doxy, TMP-SMX or clindamycin) plus incision & drainage. Don’t forget to send wound cultures for patients receiving antibiotics to help tailor therapy. 

*Note: A recent trial found high cure rates at 7-10 days follow up for abscesses less than 5cm treated with I&D plus adjunctive clindamycin or TMP-SMX for 10 days (Daum, NEJM 2017). 

Packing Wounds

Not a requirement. It can be uncomfortable for the patient. Dr Titanji mentions packing may be considered if the clinician is worried that further drainage is needed (i.e. infection was left behind). It’s not clear that packing works (List, S D Med 2016 )

Decolonization

Huang et al found that a decolonization regimen of chlorhexidine mouthwash, baths or showers with chlorhexidine, and nasal mupirocin for 5 days twice per month for 6 months reduced subsequent MRSA infection vs *education alone (Huang, NEJM 2019). Dr Titanji points out that trial adherence was 66%. She engages in shared decision making for patients who’ve had recurrent infections. She notes that decolonization often works initially, but future recurrence is common. 

Decolonization of the whole household may be superior to individuals (Fritz, Clin Inf Dis 2011). 

*Hygiene practices to prevent household spread include: frequent handwashing, wiping shared surfaces, covering wounds; avoid sharing clothes and towels; change clothes daily and wash sheets weekly (see supplementary material from Huang, NEJM 2019).

Human Bites

Clenched fist injuries often go unnoticed in the moment and therefore, present later in the course. For those patients with active infections Dr Titanji has a low threshold for hospital admission. Antibiotics need to cover anaerobes, particularly Eikenella (normal human periodontal flora). 

• Treat with IV ampicillin-sulbactam or pip-tazo 
• Amox-clav is the first line oral medication for bites
• PCN allergic?: Use a fluoroquinolone plus either metronidazole or clindamycin
• Consult hand surgery early
• Imaging typically warranted
• Tetanus booster (if >5 years since last vaccination)
• Give tetanus toxoid if patient is unvaccinated

Kashlak Pearl: Dr Titanji cautions against moxifloxacin monotherapy as there is limited experience and she’d worry about treatment failure (expert opinion). 

Preemptive antibiotic therapy for uninfected human bite wounds: Dr Titanji recommends a short course of prophylactic antibiotics and repeat evaluation of the wound.

Animal Bites

Dog bites are less likely to be infected than cat bites. Therefore, some dog bites can be followed clinically. Cats have sharp teeth that tend to puncture deeply and therefore, Dr Titanji recommends prophylactic antibiotics for most cat bites.

For infected dog or cat bites the antibiotic choices are the same noted above for human bites as are the principles for early imaging, surgical consultation and potential need for tetanus booster.

Primary vs secondary closure

Bite wounds are dirty. We must balance the pressure for a cosmetic outcome (e.g. bite wound on the face) with the increased risk for infectious complications. Therefore, Dr Titanji recommends a discussion with the surgical team about risks/benefits of approximating the wound edges vs primary closure of a wound that may still have deeper infection.

Links*

1. The First Law Trilogy by Joe Abercrombie
2. On Becoming a Healer the book and the podcast
3. Polio (book) by David Oshinsky

*The Curbsiders participates in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising commissions by linking to Amazon. Simply put, if you click on our Amazon.com links and buy something we earn a (very) small commission, yet you don’t pay any extra.

Goals

Listeners will develop a framework to approach skin and soft tissue infections including: abscess, cellulitis and bites. 

Learning objectives

After listening to this episode listeners will…

1. Diagnose cellulitis
2. Categorize skin and soft tissue infections to determine appropriate therapy
3. Determine the appropriate antibiotic choice for common skin and soft tissue infections: Abscess, cellulitis and bites wounds

Disclosures

Dr Titanji reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 

Citation

Watto MF, Titanji BK, Williams PN, Garbitelli B. “246 Take a Bite out of Cellulitis with Dr Boghuma Titanji.” The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list Final publishing date December 14, 2020.