From the Guidelines
Impetigo is primarily caused by two types of bacteria: Staphylococcus aureus and group A beta-hemolytic streptococci (Streptococcus pyogenes), as stated in the most recent and highest quality study 1. The bacteria typically enter the skin through small breaks, cuts, or insect bites, and then multiply in the superficial skin layers. Some key points to consider include:
- The infection is highly contagious and spreads through direct contact with the lesions or by sharing items like towels or clothing with infected individuals.
- Children are particularly susceptible to impetigo due to their immature immune systems and frequent close contact with other children.
- The bacteria produce toxins that cause the characteristic honey-colored crusts in bullous impetigo or the red sores of non-bullous impetigo.
- Treatment typically involves topical antibiotics like mupirocin for limited infections, or oral antibiotics such as cephalexin, dicloxacillin, or clindamycin for more widespread cases, usually administered for 7-10 days, as recommended by 1 and supported by 1 and 1. It's worth noting that while other studies, such as 1, 1, and 1, provide additional information on the diagnosis and management of skin and soft tissue infections, the most recent and highest quality study 1 provides the most relevant and up-to-date guidance on the causative pathogens of impetigo.
From the FDA Drug Label
Mupirocin ointment, 2% is indicated for the topical treatment of impetigo due to: Staphylococcus aureus and Streptococcus pyogenes. The pathogens that cause impetigo are:
- Staphylococcus aureus
- Streptococcus pyogenes 2
From the Research
Pathogens Causing Impetigo
The pathogens that cause impetigo include:
- Staphylococcus aureus
- Streptococcus pyogenes
Types of Impetigo and Their Causes
The two principal types of impetigo are:
- Nonbullous impetigo (70% of cases), caused by Staphylococcus aureus or Streptococcus pyogenes 3
- Bullous impetigo (30% of cases), caused exclusively by Staphylococcus aureus 3
Prevalence of Pathogens
Studies have shown that:
- S. pyogenes remains the principal pathogen in tropical impetigo, with a relatively high contribution of S. aureus as a co-pathogen 4
- The majority of infections are caused by S. aureus, alone (approximately 85%) 5
- Methicillin-resistance was detected in 15% of children who cultured S. aureus from either a sore or their nose 4
Treatment Considerations
Treatment options should consider the presence of both S. aureus and S. pyogenes, especially in severe and prevalent cases of impetigo 4 Topical antibiotics such as mupirocin, retapamulin, and fusidic acid are effective against both methicillin-susceptible S. aureus and streptococcal infections 3