VisualDx - Diagnosis Details - Fever and Rash: Impetigo, Bullous

684 – Impetigo

Bullous impetigo is a superficial infection of skin caused by phage group II staphylococci. It is primarily seen in children and only rarely occurs in teenagers or young adults. Constitutional symptoms and fever are rare and mild, if they occur. Outbreaks tend to occur during the summer months and in humid climates. Staphylococcus aureus can secondarily infect the lesions of varicella, causing a bullous presentation to varicella.

Methicillin-resistant S. aureus (MRSA) first emerged as an important nosocomial pathogen in the 1960s. In more recent years, community-acquired outbreaks of MRSA (CA-MRSA) have increasingly been described among healthy individuals lacking the traditional risk factors for such infections (IV drug use, incarceration, participation in contact sports, etc). In a recent study of emergency room visits for purulent skin and soft tissue infections, MRSA was identified as the etiologic agent in the majority (59%) of cases in multiple locations nationwide. Furthermore, this study determined that 57% of patients with MRSA did not receive the appropriate initial antibiotic therapy.

Look For

Vesicles that rapidly progress to flaccid, serous, or yellow, fluid-filled bullae. These are superficial bullae that easily denude, leaving a moist, red erosion that rapidly evolves to a varnish-like crust. Lesions are sharply demarcated without surrounding erythema.

Diagnostic Pearls

Bullous impetigo is very infectious and may spread among school children, especially sports teams practicing contact sports (eg, wrestling).

Differential Diagnosis & Pitfalls

If persistent and recurrent, consider primary bullous diseases such as pemphigus vulgaris, bullous pemphigoid, epidermolysis bullosa acquisita, linear IgA dermatosis, and dermatitis herpetiformis.
Bullous arthropod bites
Contact dermatitis
Poison ivy or oak dermatitis
Herpes simplex virus (HSV)
Stevens-Johnson syndrome
Tinea corporis or tinea pedis (bullous)
Drug eruption, bullous
Varicella
Sneddon-Wilkinson subcorneal pustulosis

Best Tests

Gram stain of blister fluid demonstrating gram-positive cocci. Culture and sensitivity.

Management Pearls

Very infectious in households. The infected individual should use separate towels and soap. Given the prevalence of MRSA, maintain a high index of suspicion for this diagnosis and make the initial choice of empiric antibiotic therapy accordingly. It is helpful to be aware of patterns of antimicrobial resistance within your community.

Eradication of MRSA nasal carriage may be accomplished with application of 2% mupirocin cream to the nares. The combination of rifampin plus TMP-SMX has also been shown to eradicate MRSA colonization.

Precautions: Standard and Contact (Isolate patient, wear gloves and a gown, limit patient transport, and avoid sharing patient-care equipment.)

In the US, infections due to MRSA, VRSA, Vancomycin-intermediate S. aureus, Vancomycin-resistant Enterococcus species, or Vancomycin Resistant S. epidermidis are reportable in AK, AZ, CT, DE, FL, CA, IL, IN, IA, LA, ME, MI, MN, MO, NE, NV, NY, NC, ND, OH, PA, RI, SC, SD, TN, TX, UT, VT, VA, WA, WV, WI, and WY.

In the US, infections due to invasive Group A Streptococcus are reportable in all states except AL, CO, MS, MT, ND, OR, and UT.

Therapy

Erythromycin 333 mg 3 times daily for 1 week.
Dicloxacillin 250–500 mg 4 times daily for 1 week.
Cephalexin 250–500 mg 4 times daily.

Standard cephalosporins and penicillins are of no benefit in treating MRSA. In recent studies, CA-MRSA has demonstrated a high degree of susceptibility to trimethoprim-sulfamethoxazole and rifampin (100%), clindamycin (95%), and tetracycline (92%). Inducible resistance to clindamycin should be excluded by performing a D-zone disk-diffusion test. Critically ill patients with MRSA or suspected MRSA should receive vancomycin or linezolid. Based on recent clinical trials, daptomycin and tigecycline are likely reasonable alternatives to these drugs.

References

Cohen PR. Community-acquired methicillin-resistant Staphylococcus aureus skin infections: implications for patients and practitioners. Am J Clin Dermatol. 2007;8(5):259-70. PubMed Id: 17902728

Stanley JR, Amagai M. Pemphigus, bullous impetigo, and the staphylococcal scalded-skin syndrome. N Engl J Med. 2006 Oct 26;355(17):1800-10. PubMed Id: 17065642

Moran GJ, Krishnadasan A, Gorwitz RJ, Fosheim GE, McDougal LK, Carey RB, Talan DA, EMERGEncy ID Net Study Group. Methicillin-resistant S. aureus infections among patients in the emergency department. N Engl J Med. 2006 Aug 17;355(7):666-74. PubMed Id: 16914702

Koning S, Verhagen AP, van Suijlekom-Smit LW, Morris A, Butler CC, van der Wouden JC. Interventions for impetigo. Cochrane Database Syst Rev. 2004;(2):CD003261. PubMed Id: 15106198

Norman RA. Geriatric dermatology. Dermatol Ther. 2003;16(3):260-8. PubMed Id: 14510883

Hirschmann JV. Impetigo: etiology and therapy. Curr Clin Top Infect Dis. 2002;22:42-51. PubMed Id: 12520646

Associated Findings

Appearance
No Acute Distress
Patient Appears Ill

Body Location
Anterior Neck
Arm
Cheek
Chin
Dorsum of Foot
Dorsum of Hand
Face
Foot (Feet) or Toes
Forearm
Hand or Fingers
Lateral Neck
Lower Leg
Nose
Occipital Neck
Posterior Neck
Thigh
Upper Arm

Configuration
Grouped

Distribution
Diaper Area
Head/Neck
Scattered Few

Exposures
Flies (Diptera)

Lesion
Crust
Erosion
Flaccid Bullae
Pustule
Tense Vesicle

Occupations
Health Care Worker (Medical)
Military

Signs and Symptoms
Fever (Febrile)
No Fever (Afebrile, Apyrexial)
Pruritus (Itching)

Social History
Elementary School (K-5)
Homeless
Sporting Activity
Weightlifting
Wrestler

Temporal
Developed Acutely Over Days to Weeks