Case study: Recurrent skin infections

Dr Rebecca Ratcliffe discusses a patient who presented with boils on her thigh.

Larger abscesses or cellulitis should be treated with a seven day course of antibiotics (SPL)
Larger abscesses or cellulitis should be treated with a seven day course of antibiotics (SPL)

THE CASE

A 16-year-old girl presented with multiple small boils on her left buttock. After four weeks of erythromycin (she was penicillin allergic) she failed to improve. Swabs from the wound showed a pure growth of Staphylococcus aureus and so was switched to doxycycline (based on sensitivity results). Within a week her symptoms had cleared.

Five months later she presented with further boils, this time on her right buttock. Once again she was started on erythromycin and a couple of weeks later she complained of more lesions in her axilla and thigh.

On further questioning it transpired her younger brother also suffered from similar lesions. She was referred to paediatrics for assessment and continued on erythromycin. Over the next four months she suffered from multiple disabling skin lesions on her knees, legs, buttocks and axilla, many of which led to scarring. This caused significant psychological trauma as well as pain and disfigurement.

When she was seen in secondary care, the dermatologists took swabs of an active lesion and her anterior nares and switched her to doxycycline. Her swabs tested positive for a Panton Valentine Leukocidin (PVL) positive Staphylococcus aureus. As her brother had such similar history the whole family received decolonisation treatment, when all active lesions were healed.

At follow-up six months after decolonisation, none of the family had suffered from skin lesions.

What is PVL?

PVL toxin is a major virulence factor in some strains of Staph aureus. It can be identified in both meticillin resistant Staph aureus (MRSA) and meticillin sensitive Staph aureus (MSSA).

It appears that the incidence is increasing in the UK (720 reported cases in England and Wales 2005-2006, 4,784 cases in 2009-2010), however this may be due to more heightened awareness and testing. PVL producing strains can cause boils, necrotising skin and necrotising soft tissue infections.

These infections are often recurrent or fail to respond to standard treatments. Rarely, PVL producing Staph aureuscan cause invasive infections such as necrotising pneumonia, necrotising fasciitis and osteomyelitis. Patients are usually otherwise healthy young adults who present to their GP with a history of recurrent boils or abscesses (often in different sites) over a period of weeks or months. There may be a history of clustering of skin infections within the same household or social group such as contact sports or in the gym. In such patients, GPs should consider PVL producing Staph aureus and take a swab of the current infection as well as anterior nares (and consider other sites). It should be sent to the local microbiology laboratory for microscopy, culture and sensitivity, with the form specifically requesting testing for PVL producing Staph aureus and stating appropriate clinical details.

Managing PVL

Minor infections do not necessarily need systemic antibiotics but may need incision and drainage.

Larger abscesses or cellulitis should be treated with a seven-day course of antibiotics. Public Health England (PHE) guidance suggests flucloxacillin or clindamycin for MSSA, rifampicin and another antibiotic for MRSA, guided by antimicrobial susceptibility testing when available. Active lesions should be covered up and the importance of personal hygiene should be highlighted (not sharing towels/bath water). Some patients may need a longer course or alternative antibiotics so they should be advised to return if lesions do not heal.

All patients should be decolonised once all active lesions have resolved.

PHE suggest a topical decolonisation regimen of five days (chlorhexidene 4% body wash/shampoo daily and mupirocin ointment anterior nares three times a day). If there is a history of probable colonisation in a close contact (partner/household member with skin infection) then it is prudent to assume all contacts need decolonisation with the regimen as above. If, however, there is no such history, it may be more appropriate to screen household members before starting decolonisation.

Patients and their contacts should be aware of recurrence of PVL related disease and be advised to make contact with their GP if this happens. Patients who work in occupations where they will have close contact with vulnerable groups should be referred to their local occupational health team. In certain instances exclusion from some duties may be necessary pending treatment.

  • Dr Ratcliffe is an ST3 GP registrar, Llanederyn Health Centre, Cardiff

Resources

  • Guidance on the diagnosis and management of PVL-associated Staphylococcus aureus infections (PVL-SA) in England, Health Protection Agency 2008, www.hpa.org.uk
  • PVL-Staphlococcus aureus infections: an update, Health Protection Agency 2011, www.hpa.org.uk
  • How is PVL positive S. aureus skin infection diagnosed? BMJ 2011; 343: d5343.

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