Impetigo
Summary
This article discusses the basics of impetigo, the etiological agent, its classification, management, and complications.
Basics
Impetigo is a common superficial skin infection that is caused be either Staphylococcus aureus or group A B-hemolytic streptococci. Commonly present as cutaneous vesicles surrounded by an area of inflammation. As the disease progresses, the vesicles may rupture resulting in a honey-colored crust on an erythematous base. It may present as individual, satellite lesions. Some of the predisposing factors include malnutrition, poor hygiene, other dermatosis (atopic dermatitis, contact dermatitis, insect bites, pediculosis, and scabies).
Classification
- Bullous Impetigo
- Caused by Exfoliative toxins (A) released by S. aureus
- bullous impetigo, the blisters are localized while in Scalded Skin Syndrome the blisters are disseminated
- Commonly occurs in the diaper area, axillae, neck
- Regional lymphadenopathy is not common
- Non-Bullous Impetigo (Crusted)
- More common, approximately 70%
- Commonly occurs in the exposed areas such as limbs, face
- Regional lymphadenopathy common
- May resolve without treatment in 2-3 weeks
Management
General
- Good personal and household hygiene
- Reduces carriage of the organism and spread.
- Therefore very important to always wash your hands.
- Wash and soak lesions in soapy water to soften and remove the crusts.
- Soaps and substances such as chlorhexidine and povidone-iodine may be used.
Medical
- Antibiotics
- Flucloxacillin 500mg PO 6 hourly for 5 days.
- If the patient has a penicillin allergy, use a macrolide such as Azithromycin 500mg PO daily for 3 days.
- NB: Keep in mind how S. aureus can produce a B-lactamase which can hydrolyze the B-lactam ring of many B-lactam antibiotics. For this reason, antibiotics that are resistant to the B-lactamase may be used (oxacillin, cloxacillin, dicloxacillin). Macrolides such as Erythromycin, Clarithromycin, and Azithromycin can also be used. Amoxicillin needs to be combined with a B-lactamase inhibitor (Clavulanic acid) in order to have adequate cover. This combination is known as Co-Amoxiclav. Other drugs such as Clindamycin, Co-trimoxazole, Minocycline, Tetracycline, and Fluoroquinolones are reserved for use in MRSA.
- The EML Guidelines advise on systemic oral antibiotics, but topical antibiotics such as Mupirocin and Fusidic acid may be used.
Complications
There is the possibility that the patient may develop post-streptococcal glomerulonephritis.
References and Further Reading
1. The National Department of Health, South Africa: Essential Drugs Programme. Primary Healthcare Standard Treatment Guideline and Essential Medicine List. 7th ed. South African National Department of Health; 2020.
2. Pereira, L.B. (2014) “Impetigo - review,” Anais Brasileiros de Dermatologia, 89(2), pp. 293–299. Available at: https://doi.org/10.1590/abd1806-4841.20142283.
3. Figure 1: Pereira LB - Anais brasileiros de dermatologia (2014 Mar-Apr) CC BY-NC 3.0
4. Figure 2: James Heilman, MD - Own work CC BY-SA 4.0
2. Pereira, L.B. (2014) “Impetigo - review,” Anais Brasileiros de Dermatologia, 89(2), pp. 293–299. Available at: https://doi.org/10.1590/abd1806-4841.20142283.
3. Figure 1: Pereira LB - Anais brasileiros de dermatologia (2014 Mar-Apr) CC BY-NC 3.0
4. Figure 2: James Heilman, MD - Own work CC BY-SA 4.0
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