CELLULITIS
Presented by Wendy Gerstein, MD
Thursday School
7/24/14
QUESTION 1
 38 yo woman is evaluated in urgent care for redness and pus that
developed near a scratch on her right shin. On PE: T=37.3 C, bp
135/75, p 78, rr 14. A 3x2 cm erythematous, warm patch is present
over the right shin with associated purulence/pus, but no fluctuance,
drainable abscess or lymphadenopathy is present. WBC is 10k with
70% N and 30% L. She has no drug allergies.
 Which of the following is the most appropriate outpatient therapy?
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A) Cephalexin (Keflex)
B) Dicloxacillin
C) Trimethoprim-sulfamethoxazole (Bactrim)
D) Amoxicillin
QUESTION 2
 A 27 yo male is evaluated for redness that developed over his left
forearm at the site of a mosquito bite. He is otherwise healthy and takes
no medications. PE: T= 37.2 C, bp 120/70, p 68, rr 14. There is an
erythematous 3x3 cm patch on the left forearm. The area is warm to the
touch with no evidence of purulence, fluctuance, crepitus, or
lymphadenopathy.
 Which of the following is the most appropriate empiric outpatient
therapy?
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A) Doxycycline
B) Cephalexin (Keflex)
C) Fluconazole
D) Trimethoprim-sulfamethoxazole (Bactrim)
E) Metronidazole
ANSWERS
 Answer for question 1: C, Bactrim
 Answer for question 2: B, Cephalexin (Keflex)
 What is the one important difference between the two cases?
CELLULITIS
CELLULITIS
 Clinical presentation: local tenderness, pain and
erythema that rapidly increases. Borders are not elevated
or sharply demarcated (as in erysipelas). May have
patchy involvement with skip areas.
 Systemic manifestations include mild fever, chills and
malaise, can progress to sepsis.
CELLULITIS
 Complications can include bacteremia, abscesses, overlying
skin necrosis, muscle/joint/bone involvement.
 Risk factors: lymphedema, chronic venous stasis, trauma,
skin breakdown (fungal infection), diabetes,
immunosuppression, altered anatomy/surgery.
 Patient who are showing systemic signs (i.e., meet SIRS
criteria) should be admitted for initial treatment with IV
antibiotics, then transition to appropriate oral therapy.
ORGANISMS
 Most common organisms: streptococci (group A β-hemolytic
[GABHS] most likely) and Staphylococcus aureus.
 Think strep if “peau d’orange” skin changes and lymphangitis are
present.
 Think S. aureus (and CA-MRSA, MRSA) if purulence or abscess
present.
 Erysipelas: superficial, well-demarcated, intensely erythematous,
indurated borders. GABHS.
CELLULITIS
 Post-operative infections with Group A strep are
uncommon but can spread rapidly and develop into
bacteremia/sepsis. Can occur within 6-48 hours after surgery.
• Hypotension may be the first signs of infection prior
to cellulitis.
• Thin serous discharge may be expressed from the
surgical site that is gram stain positive for streptococci.
CELLULITIS
 Diabetics: at risk for polymicrobial infections including:
• GPC including S. aureus, Enterococcus, various
streptococcal species, peptostreptococcus (anaerobe).
• GN aerobes: Enterobacter, Acinetobacter, and
Pseudomonas.
• GN anaerobes: Bacteroides
ANTIBIOTICS IN
CELLULITIS
 At minimum, need empiric coverage for strep species and S.
aureus.
 Include a β-lactam antibiotic with activity against penicillinaseproducing S. aureus (MSSA).
 If not severe may treat as outpatient.
• Cephalexin or dicloxacillin have good strep and MSSA coverage.
• Clindamycin may be used for strep and CA-MRSA (know local
antibiogram).
• If suspect MRSA then consider TMP-SMX or doxycycline (can add
clindamycin or amoxillin if need improved strep coverage). May also
consider Linezolid.
ANTIBIOTICS CONT.
Inpatient antibiotic choices:
• Strep/MSSA choices: nafcillin, cefazolin, clindamycin
• CA-MRSA/MRSA: clindamycin (know antibiogram),
vancomycin, daptomycin, linezolid, ceftaroline.
• Diabetics: broaden to amp-sulbactam (moderate infection),
pip/tazobactam (severe) plus MRSA coverage. Remember
ceftriaxone does not have anaerobic coverage.
• Septic patient: start broad, then narrow coverage as cultures
return.
CA-MRSA/MRSA
MRSA CELLULITIS GUIDELINES
 For a cutaneous abscess incision and drainage is the primary
treatment.
 When is adjunct antibiotic therapy recommend for
abscesses?
• Severe or extensive (multiple sites) or rapid progression
in presence of cellulitis.
• Signs of systemic illness.
• Associated comorbidities or immunosuppressed.
• Extremes of age.
MRSA CELLULITIS GUIDELINES
• Abscess in area difficult to drain (face, hand and
genitalia).
• Associated with septic phlebitis.
• Lack of response to incision and drainage.
MRSA CELLULITIS GUIDELINES
Treatment of purulent cellulitis:
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Empiric treatment for CA-MRSA/MRSA.
Bactrim, clindamycin, doxycycline or minocycline, linezolid.
If need MRSA and streptococcus coverage: clindamycin; or
bactrim or doxycycline with amoxicillin; or linezolid alone.
If inpatient treat with IV antibiotics initially: vancomycin,
clindamycin, linezolid, daptomycin, ceftaroline.
AJM 2010;123:942-950
 Retrospective cohort study in 2005-2007 comparing bactrim to
cephalexin to clindamycin for mild to moderate cellulitis.
 405 patients in study:
• Excluded patients with severe cellulitis.
• MRSA recovered in 72/117 positive culture specimens.
• Successful treatment
• TMP-SMX 138/152 (91%)
• Cephalexin 134/180 (74%)
• Clindamycin 34/40 (85%)
HOW LONG TO TREAT??
 IDSA guidelines: five days of treatment is a effective as a 10
day course for uncomplicated cellulitis.
 Based on a 2004 study in which 87 patients were treated
with levofloxacin 500mg po qd x 5 days compared with 43
patients who received levofloxacin for 10 days. Complete
resolution on day 14 was similar and day 28 recurrence rate
was similar.
 However levofloxacin has a longer ½ life than β-lactam antibiotics
that are used more commonly.
 IDSA recommends evaluation at day 5 – if resolved can stop
antibiotics. If persisting, continue to 10 days.
 Arch Intern Med 2004;164:1169-1674.
P RO P H Y L A X I S F O R
R E C U R R E N T C E L LU L I T I S
 First identify and treat predisposing conditions (edema, obesity,
eczema, venous insufficiency, fungal foot infections).
 Oral penicillin 250-500 mg po bid for one year should be
considered in patients who have >3 episodes per year despite
attempts to treat or control predisposing factors. Can continue past
one year (indefinitely) if factors persist and patient tolerating.
 IDSA guidelines, 2014. Based on two studies, PATCH 1 and
PATCH 2.
SPECIAL CIRCUMSTANCES
FOR CELLULITIS
 Erysipelothrix rhusiopathiae (erysipeloid) – gram positive
facultative anaerobic rod. Causes an indolent cellulitis occurring in
persons who handle saltwater fish, shellfish, poultry, meat and
hides. Treat with penicillin or cephalosporin.
 Aeromonas hydrophila – gram negative rod that causes an acute
cellulitis after laceration while swimming in fresh water. Also
associated with medicinal leeches. Treat with ciprofloxacin +/doxycycline.
SPECIAL CIRCUMSTANCES
FOR CELLULITIS
 Vibrio vulnificus (curved gram negative rod) causes cellulitis,
bullous lesions or necrotic ulcers after exposure to warm coastal
water or exposure to drippings from raw seafood.
 Infection can progress to necrosis requiring surgical
debridement.
• Bacteremia with septicemia can occur after eating raw oysters, can
develop associated skin findings.
• Alcoholic cirrhosis, hemochromatosis and thalassemia increase the risk of
septicemia and development of necrotizing fasciitis (due to iron
overload).
• Treat with doxycycline plus ceftriaxone.
E . R H U S I O PA T H I A E A N D V I B R I O
E. rhusiopathiae
Vibrio species
OTHER
 Animal or human bite:
• Clean wound, check tetanus status of patient, rabies status of
animal.
• Usually polymicrobial infection due to mouth and skin flora.
• Empiric antibiotic coverage with Augmentin or unasyn.
• Penicillin allergic : fluoroquinolone or doxycycline (plus
clindamycin or metronidazole for anaerobic coverage).
Drugs 2003;63:1459-1480
IMMUNOSUPPRESSED (CANCER
PAT I E N T S, A I D S, T R A N S P L A N T )
 Differential for skin lesions much broader in this subset – biopsy is
necessary is most cases, get early if possible.
 Need to consider infection, drug reaction/eruption, Sweet
syndrome, malignancy, leukocytoclastic vasculitis, erythema
multiforme.
QUESTION 3
 40 yo male evaluated in ER for LUE skin infection. He works at the
VA, where he sustained a minor laceration 3 days ago when trying to
prevent a patient’s fall. He cleaned and bandaged the laceration but
developed purulence, surrounding tenderness, and now with fever over
last 24 hours. On exam T=38.5, bp 125/75, p 90, rr 18. An area of
purulent cellulitis measuring 4x5 cm surrounding a 1.5 cm laceration is
present. No fluctuance. Rest of exam wnl. WBC 14k, 90% neutrophils.
UA nl. Radiograph of arm only shows soft tissue swelling.
QUESTION 3 CONTINUED
 Which of the following beta-lactam antibiotics is most appropriate
for treatment of this infection?
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A) Meropenem
B) Oxacillin
C) Zosyn (pip/tazobactam)
D) Ceftaroline
E) Ceftriaxone
QU E S T I O N 3 C O N T I N U E D
 Correct answer is D, ceftaroline – need MRSA coverage due to
purulence, health-care associated. Vancomycin would have been
correct if offered as a choice.
NECROTIZING FASCIITIS
 Deep tissue infection that spreads rapidly along fascial planes.
 Clinical features that suggest a necrotizing infection include:
• Severe constant pain, pain out of proportion to exam.
• Bullae: related to occlusion of deep blood vessels that traverse the
fascia or muscles.
• Skin necrosis or ecchymosis that precedes the skin necrosis.
• Gas in the soft tissues.
• Edema that extends beyond the margin of the erythema.
• Cutaneous anesthesia.
• Systemic toxicity (fever, leukocytosis, delirium, renal failure).
• Rapid spread, especially concerning if on antibiotic therapy.
• Subcutaneous tissues feels wooden-hard.
NECROTIZING FASCIITIS
NECROTIZING FASCIITIS
NECROTIZING FASCIITIS
 Type I- Polymicrobial
• Includes at least one anaerobic species, commonly Bacteroides or
Peptostreptococcus;
• Plus one or more facultative anaerobic species such as streptococci;
• Plus members of Enterobacteriaceae (E. coli, Enterobacter, Klebsiella,
Proteus.
• Associated with:
• Surgical procedures involving the bowel or penetrating
abdominal trauma.
• Decubitus ulcer or a perianal abscess.
• Site of injection in IVDA.
• Spread from a Bartholin abscess or minor vulvovaginal
infection.
NECROTIZING FASCIITIS
 Type II (aka hemolytic streptococcal gangrene): Group A
streptococci are isolated either alone or with S. aureus
• Usually involves the limbs with 2/3 in the lower
extremities.
• Associated with underlying disease:
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DM
Arteriosclerotic vascular disease
Venous insufficiency with edema
Chronic vascular ulcer
Post varicella infection – commonly due to S. pyogenes
• Mortality is high- 50-70% in patients with hypotension
and organ failure. Lancet 1994;344:1111-5
NECROTIZING FASCIITIS
 Type III- Gram negative monomicrobial
• Vibrio spp
• V. damselae and V. vulnificus
• Mortality of 30-40% despite prompt diagnosis and aggressive
therapy. (J of Hos Infec 2010;75:249-257)
 Type IV- Fungal
• Cases of candida NF very rare, mostly in immunocompromised.
• Zygomycotic NF (Mucor and Rhizopus spp) affect
immunocompetent patients after severe trauma.
• Burns or trauma wounds with aspergillus or zygomycetes should be
consider infected (not just colonized). (J of Hos Infec 2010;75:249257
NECROTIZING FASCIITIS
Determinants of mortality
• Retrospective study in 2005 in Taiwan.
• Studied both type I and type II necrotizing fasciitis.
• 87 pts. Found increased mortality with:
• Age >60
• 2 comorbidities, especially DM and liver disease
• Thrombocytopenia
• Abnormal liver function tests
• Increased BUN and Cr
• Low serum albumin level
• Patients who underwent emergent debridement in <24
hours had a lower mortality than patients whose surgery
was delayed (26% vs 45.9%).
• Total of 30/87 patients died in this study (34.4%).
•
J Micro Imm Infect 2005;38:430-435
NECROTIZING FASCIITIS
Studies
• CT scan or MRI may show edema and/or gas extending
along the fascial plane.
• In practice, clinical judgment is the most important element
of diagnosis.
• Cultures obtained from deep tissue during surgery are
helpful.
• Skin cultures usually contaminated with skin flora.
NECROTIZING FASCIITIS
 Treatment:
• Surgical intervention:
• No response to antibiotic therapy.
• Profound toxicity with fever, hypotension, or advancement of skin
and soft-tissue infection during antibiotic therapy.
• Local wound shows any necrosis with easy dissection along fascia by
blunt instrument.
• Any soft tissue infection accompanied by gas.
• Most patients with necrotizing fasciitis should return to the OR
within 24-36 hours after first debridement and daily thereafter
until surgical team finds no further need for debridement.
NECROTIZING FASCIITIS
 Empiric coverage: very broad
• Piperacillin-tazobactam , plus vancomycin OR
• Meropenem/imipenem plus vancomycin.
• PCN allergy: Cefotaxime, plus metronidazole or clindamycin, plus
vancomycin.
• Severe PCN allergy: clindamycin or metronidazole, plus
aminoglycoside or fluoroquinolone, plus vancomycin.
NECROTIZING FASCIITIS
 Streptococci infections
• PCN: most streptococci are susceptible in the US.
• Clindamycin: in vitro studies demonstrate both toxin
suppression and modulation of cytokine TNF production.
• Give both initially.
NECROTIZING FASCIITIS
 IVIG – not enough evidence to recommend therapy.
 HBO – hyperbaric oxygen – not enough evidence to recommend
therapy.
 Questions…