impetigo%20-and-%20ecthyma
IMPETIGO & ECTHYMA
Impetigo is a very contagious, superficial, bacterial skin infection that easily spreads among people in close contact.
Most cases occur in children and resolve spontaneously without scarring in approximately 14 days.
Ecthyma is a deeply ulcerated form of impetigo that extends to the dermis.
It has "punched-out" ulcers with yellow crust and elevated violaceous margins.
Most cases occur in children and elderly.
It may be a de novo infection or superinfection.

Principles of Therapy

  • Duration of treatment is tailored according to clinical improvement
    • If unresponsive or deteriorating, it is reasonable to extend beyond 7 days while waiting for the culture & sensitivity (C&S) results

Topical Antibiotic Therapy

  • May be appropriate in localized nonbullous impetigo located away from the mouth (child may lick topical antibiotics if applied near the mouth)
  • Used to treat single lesions or small areas of involvement (localized impetigo)
  • Must be applied after crust removal to enhance penetration
    • Soften crusts w/ a wet cloth compress
    • Removal of scabs during the process of healing is not recommended
  • Use should be limited to 2 weeks due to risk of contact sensitization & antibiotic resistance development

Oral Antibiotic Therapy

  • Preferred treatment in patients w/ systemic symptoms, widespread nonbullous impetigo, lesions near the mouth, bullous impetigo, ecthyma patients in cases where there is evidence of deep involvement (eg cellulitis, furunculosis, etc), recurrent infection or in immunocompromised, those unable to tolerate topical antibiotics
  • Choice of agent will depend on suspected organism, local resistance patterns, cost & product availability
  • Parenteral antibiotics may be needed for widespread ecthyma

Pharmacotherapy

Topical Antibiotics

Fusidic Acid

  • 1st-line topical antibiotic
  • Effects: Has been proven to be as clinically effective as Mupirocin
    • Active against staphylococci (including Methicillin-resistant strains) & streptococci

Other Topical Antibiotics

Bacitracin

  • Used for many years as topical therapy for localized impetigo
  • Effects: Has been shown to be effective against S aureus & group A streptococci

Mupirocin

  • Effects: Has been proven to be as effective as Fusidic acid & several oral antibiotics (eg Ampicillin, Dicloxacillin, Erythromycin & Cefalexin) for treatment of impetigo & produces fewer side effects than oral agents
    • Considered as 2nd-line of treatment after Fusidic acid, as it is active against staphylococci (including Methicillin-resistant strains) & streptococci
  • Carriers of S aureus in their nares are treated w/ mupirocin ointment applied nasally

Retapamulin

  • New agent for treating impetigo w/ a short treatment duration of only 5 days
  • Considered as a 2nd line treatment because of its cost
  • Suitable alternative to Fusidic acid
  • Effects: Active against S aureus & streptococci
    • In vitro data show activity against Methicillin-resistant staphylococci

Oral Antibiotics

Antistaphylococcal Penicillins

  • Dicloxacillin & Flucloxacillin
    • For infections caused by penicillinase-producing staphylococci
    • May be used to initiate therapy when staphylococcal infection is suspected
    • Very effective but less tolerated compared to Cefalexin
    • Does not cover Methicillin-resistant Staphylococcus aureus (MRSA)
  • Amoxicillin + Clavulanate
    • Indicated for Impetigo & other skin & soft tissue infection caused by Methicillin-susceptible Staphylococcus aureus (MSSA)

Cephalosporins (1st Generation)

  • Excellent activity against MSSA & S pyogenes & is generally well-tolerated
  • Do not cover MRSA

Cephalosporins (2nd Generation)

  • Cefaclor, Cefprozil & Cefuroxime are among the choices

Cephalosporins (3rd Generation)

  • Variable in their activity against Gram-positive organisms especially MSSA & no inherent advantage to the broader Gram-negative coverage
    • Broad spectrum of activity tends to exert an increased selective pressure for emergence of antibiotic resistance

Macrolides

  • Alternative for Penicillin-allergic patients
  • Eg Azithromycin, Clarithromycin or Roxithromycin
    • May be advantageous especially in instances of intolerance to Erythromycin but do not provide cure rates superior to Erythromycin
  • Erythromycin
    • Typically considered treatment of choice unless Erythromycin resistance is widespread in the community
    • Does not cover MRSA

Other Oral Antibiotics

Co-trimoxazole

  • Has very good activity against community-acquired MRSA but not to streptococci

Clindamycin

  • Good choice for susceptible MRSA infections; however, there is a potential development of resistance w/ high-inoculum infections caused by Erythromycin-resistant strain

Linezolid

  • Good choice for mild to moderate bullous impetigo in patients from communities w/ high MRSA resistance

Tetracyclines

  • Eg Minocycline, Doxycycline
  • May be considered for mild to moderate MRSA infections
  • Contraindicated in children ≤8 years & during pregnancy

Non-Pharmacological Therapy

  • Hygiene measures alone are not recommended even for localized lesions since untreated impetigo is highly communicable & may become generalized
  • Topical antiseptics (eg Hydrogen peroxide cream) are not recommended due to limited evidence regarding its effectiveness & its tendency to cause skin reactions

Referral

  • A referral to a pediatrician or dermatologist may be considered when:
    • Diagnosis is unclear
    • Infection is extensive, severe, or unresponsive to maximal therapy in primary care setting
    • Recurrence is frequent
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