Consensus guideline for the management of common bacterial skin infections in primary care continued

Secondary bacterial skin infections

• Infected atopic dermatitis/eczema:
  • presenting features include weeping skin, pustules, crusts; rapidly worsening dermatitis, or flare up of eczema unresponsive to standard treatment

• Pressure sores and leg ulcers:
  • bacteria are inevitably found at sites of pressure sores and leg ulcers, where their presence represents a continuum from asymptomatic colonisation through to overt infection. Majority of these cases do not require antibiotics. Most important signs of infection are:
    • pus formation
    • surrounding cellulitis
    • evidence of underlying bone infection
    • systemic symptoms (fever, malaise, chills, rigors)

Investigations

• Microbiological investigations are not routinely required for most types of infection. Swabs rarely help in establishing a diagnosis of skin infection, because the common skin pathogens are also common skin commensals. The main purpose of collecting swabs is to guide selection of appropriate antibiotics in serious or complex cases, for instance:
  • where the lesions are very extensive or severe
  • where the infection is recurrent (consider also nasal swab for staphylococcal carriage in this situation, also consider swabbing major household contacts)
  • where the patient is suspected as being part of an outbreak (especially in impetigo)
  • when there is an increased likelihood of antibiotic resistance (e.g. patient has had close contact with someone with MRSA)
  • from pressure sores and leg ulcers, where there are signs of overt spreading infection to surrounding tissues, and/or systemic symptoms. The range of potential pathogens is much wider than with other skin infections

• When swabbing is indicated, swab wet areas of the skin where there is discharge or pus

Management

Microbiology and antibiotic susceptibilities

• S. aureus is by far the most common bacterial cause of skin infections, group A streptococcus being the only other common cause of primary infections

• Oral antibiotics:
  • antibiotic resistance patterns are currently predictable enough to permit prescribing of oral β-lactams (e.g. penicillin, flucloxacillin, cephalosporins) and macrolide antibiotics (e.g. clarithromycin, azithromycin) without microbiological confirmation
  • occasionally other antibiotics, such as rifampicin, clindamycin, or tetracyclines are used after discussion with a microbiologist or dermatologist

Consensus guideline for the management of common bacterial skin infections in primary care continued

• Topical antimicrobials:
  • there is concern about increasing resistance to fusidic acid, the most commonly prescribed topical antibiotic
    • resistance can develop rapidly during first treatment
      • may not be clinically significant where a short course of treatment is expected to cure the patient (e.g. impetigo)
      • more important where treatment does not result in long-term cure, because recurrent infections are likely to be caused by fusidic acid-resistant strains
    • other strains of S. aureus possess a gene that confers stable fusidic acid resistance
    • epidemics of impetigo caused by stable fusidic acid-resistant strains of S. aureus have been described
  • diagnostic microbiology laboratories report increasing fusidic acid resistance rates in S. aureus from skin infections. However, the true prevalence of fusidic acid resistance is uncertain, because only patients who have failed initial-line treatment are likely to have swabs collected for microbiological examination
  • mupirocin is probably best reserved for decolonisation treatment of patients with MRSA, and is not recommended for widespread use to treat MSSA infections
  • retapamulin is a novel topical pleuromutilin antibacterial. It is active against staphylococci and streptococci, and appears to have a low potential for the development of resistance or cross-resistance
  • for nasal decolonisation use either mupirocin (nasal ointment) or chlorhexidine/neomycin

• Topical antiseptics:
  • concern about antibiotic resistance has reignited interest in these. However, there are few published data on their use
  • povidone–iodine antiseptic ointments can be used for infected wounds and folliculitis
  • chlorhexidine-containing formulations (ranging in concentrations of 1−4%) are used mainly as antiseptic cleaning agents for areas of skin trauma or breach
  • for the treatment of established infections, most interest has focused on 1% hydrogen peroxide in stabilised cream. It has been found to be well tolerated, and there are data, albeit limited, to suggest that it is non-inferior to topical antibiotics in treating some dermatological infections, including impetigo. There is no known risk of emergence of antibiotic resistance associated with its use

Treatment approaches

General advice

• Antibiotic-containing products should be used for no longer than 2 weeks
• Advise patient to cleanse their skin prior to any topical treatment:
  • use a clean flannel each time
  • attempt to rub off any crust and scab (this applies to any condition presenting with impetiginized scabs, such as impetigo or infected eczema)
  • wash hands after touching affected areas of the skin, and after applying cream

Primary skin infections

• Impetigo:
  • often self-limiting, but antimicrobials are usually prescribed to hasten clinical cure and to interrupt spread to other areas
  • topical antibiotics (e.g. fusidic acid) are as effective as systemic antibiotics, and may be preferred because of better compliance and tolerability
  • topical hydrogen peroxide cream is a possible alternative

Consensus guideline for the management of common bacterial skin infections in primary care continued

• Folliculitis, furuncles, and carbuncles:
  • treatment of folliculitis should include a search for, and avoidance of, any factors predisposing to infection
  • mild cases usually require no specific antimicrobial treatment, however, the use of antiseptic wash (e.g. chlorhexidine) may help
  • alternatively, an emollient containing an antibacterial agent may be used, but there is little evidence to support this approach
  • for more severe localised cases, a topical antibiotic or antiseptic cream may be used; for generalised cases, an oral antibiotic is easier to administer
  • furuncles and small carbuncles may resolve without treatment. Otherwise treatment is with an oral anti-staphylococcal agent (e.g. flucloxacillin, clarithromycin). Early surgical drainage of collections of pus should be considered, particularly for lesions that are large and fluctuant

• Cellulitis and erysipelas:
  • prescribe a high-dose oral antibiotic for 7 days:
    • amoxicillin (500 mg three times a day) or ampicillin (500 mg four times a day)
    • use co-amoxiclav (500/125 mg three times a day) where staphylococcal infection may be present
    • if allergic to penicillin, use erythromycin (500 mg four times a day) or clarithromycin (500 mg twice a day)
    • before treatment, consider drawing around the extent of the infection with a permanent marker pen so spread of the cellulitis can be tracked. Alternatively, measure and photograph the affected area

Secondary skin infections

• Infected atopic dermatitis/eczema:
  • this guideline recommends that topical antibiotics should not be prescribed as the patient may self-medicate on an ad hoc basis, promoting antibiotic resistance
  • localised areas may be treated with a:
    • topical antiseptic combined with a corticosteroid
    • topical antiseptic (e.g chlorhexidine, 1% hydrogen peroxide cream)
  • for extensive areas of infected eczema, consider oral anti-staphylococcal antibiotics, such as flucloxacillin or clarithromycin

• Pressure sores and leg ulcers:
  • where possible, antimicrobial treatment should be delayed until microbiology results are available because the range of potential pathogens is wide and antibiotic-resistant pathogens are common. Consider treating clinically overt infections only
  • topical antibiotic therapy is not indicated due to the lack of evidence of efficacy, and concern about antibiotic resistance. However, topical metronidazole may be used to help reduce the odour from infected wounds
  • a 1% silver sulfadiazine cream may be used for topical treatment of leg ulcers infected with Pseudomonas aeruginosa
  • use of antiseptics, either as topical agents or incorporated into dressings, does not carry a risk of antibiotic resistance, but their value has not been clearly established. A 1% hydrogen peroxide cream may improve the microcirculation and decreases skin free radicals, thus improving healing

Consensus guideline for the management of common bacterial skin infections in primary care continued

Algorithm for the management of common bacterial skin infections in primary care

Referral to secondary care

• Indications for referral to secondary care:
  • the diagnosis is uncertain
  • severe or rapidly deteriorating condition
  • severe systemic illness
  • comorbidities that may complicate or delay healing
  • lesions that are unresponsive to maximal treatment in primary care
  • infections that recur frequently
  • underlying skin disorder that cannot by optimally managed in primary care

about this working party guideline…
sponsor—	Derma UK was able to recommend experts for the working party group and comment on the scope and title, with final decisions resting with the Chair. Derma UK had the opportunity to comment on the technical accuracy of this guideline but the content is independent of and not influenced by Derma UK
working party members—	Jim Gray (Chair, consultant microbiologist), Omar Ali (formulary development pharmacist), Riadh Dawood (GPwSi dermatology), Sheila Robertson (dermatology liaison nurse specialist), Roland Strauss (consultant dermatologist), Shernaz Walton (consultant dermatologist)
further information—	call MGP Ltd on 01442 876100 for a copy of the full guideline