S. aureus skin infections in New Zealand have increased significantly over the past decade.11 More
people are being hospitalised with skin infections, and there is an increase in the number of infections being reported
in the community.11 The incidence rate of patients hospitalised with S. aureus skin infections in
the Auckland DHB region increased from 81 cases per 100 000 people in 2000 to 140 cases per 100 000 people in 2011, which
represents an increase of approximately 5% per year.11 Māori and Pacific peoples, adults aged over 75 years,
children aged under five years and people living in more deprived areas have been found to have a higher incidence of
hospitalisation for S. aureus infection.11 Factors contributing to the high rates of S. aureus infections
in New Zealand are thought to include delayed access to health care, increasing overcrowding in households and declining
socioeconomic circumstances in some population groups.11
With the high rates of S. aureus skin infections in New Zealand and the increasing emergence of resistant strains,
it is important that measures are put in place to reduce the risk of recurrent infections, especially among households.
This primarily involves educating patients and their families about infection control measures and the principles of good
hygiene. A formal decolonisation regimen, using topical antibiotic and antiseptic techniques, is not necessary for all
patients, but may be appropriate for those with recurrent staphylococcal abscesses.
Decolonisation of S. aureus in patients with recurrent abscesses
Patients presenting in primary care with recurrent staphylococcal abscesses (furuncles or carbuncles) are likely to
be carrying a high bacterial load of S. aureus (some with MRSA), which is causing multiple re-infections when
skin becomes damaged, e.g. through scratching or injury. The most common site of staphylococcal colonisation is inside
the nostrils. Other frequently colonised sites include the groin, perineum, axillae and pharynx. There is conflicting
evidence as to whether undergoing staphylococcal decolonisation results in fewer skin infections (see: “Evidence
of effectiveness of decolonisation measures”. However, if a patient with recurrent staphylococcal abscesses
(or their parents/carers) is likely to be compliant with a decolonisation regimen, it is reasonable to try this. Treatment
to eliminate S. aureus colonisation in the most affected member of the household is usually all that is required
to prevent recurrences in all household members.
Decolonisation should only begin after acute infection has been treated and has resolved.
The first step is to take a nasal swab to determine whether the patient has S. aureus nasal colonisation and
if so, whether the S. aureus colonising the patient is sensitive to fusidic acid or mupirocin:
- If S. aureus is present and the isolate is sensitive to fusidic acid the patient should
be treated with fusidic acid 2% cream or ointment, applied inside each nostril (with a cotton bud or finger), twice daily,
for five days.
- If S. aureus is present and the isolate is resistant to fusidic acid, but sensitive to mupirocin,
the same treatment regimen should be undertaken, but with mupirocin 2% ointment.
- If S. aureus is not present or if the isolate is resistant to both fusidic acid and mupirocin,
topical treatment is not indicated. Systemic antibiotics may be required in some patients with particularly resistant
strains of S. aureus;17 discuss this with an infectious diseases specialist.
Bleach baths or antiseptic washes should also be used
To help reduce the bacterial load, patients undergoing S. aureus decolonisation should also be advised to shower
or bathe for one week using an antiseptic.
For a bleach bath, add 1 mL of plain unscented 5% bleach per 1 L of bathwater (or 2 mL of 2.2% bleach per 1 L of water).
Products that contain added detergent (e.g. Janola) are not recommended. N.B. A regular-sized bath filled to a depth of
10 cm contains approximately 80 L of water and a baby’s bath holds approximately 15 L of water.19
After immersing in the bath water for 10 – 15 minutes, rinse with fresh water. The bleach bath should be repeated two
to three times within the week.
A patient/carer handout on instructions for a bleach bath is available from: www.kidshealth.org.nz/sites/kidshealth/files/pdfs/bleach_bath_handout.pdf
Alternatively, patients may shower daily for one week, using triclosan 1% or chlorhexidine 4% wash. The wash can be
applied with a clean cloth, particularly focusing on the axillae, groin and perineum. Although difficult in a showering
situation, the antiseptic should ideally be left on the skin for at least five minutes before being rinsed off. Hair can
be washed with the antiseptic also.17
Bleach baths or antiseptic washing can be carried out intermittently after the initial decolonisation period, to help
prevent recurrence of infection.17 This can also be recommended for patients with recurrent skin infections
who have not undergone formal decolonisation.17
As S. aureus can also colonise the pharynx, an antiseptic throat gargle (e.g. chlorhexidine 0.2% solution,
three times daily) is also recommended for the duration of formal decolonisation treatment.17
Linen and clothing can also be decolonised
To support the decolonisation regimen, potentially contaminated clothing, towels, facecloths, sheets and other linen
in the household should be washed then dried on a hot cycle in a clothes dryer, or dried then ironed. Clothing and linen
that is white or colourfast can be washed with diluted household bleach. Washing is recommended twice within the one week
Ideally, the household should also replace toothbrushes, razors, roll-on deodorants and skin products. Hair brushes,
combs, nail files, nail clippers can be washed in hot water or a dishwasher.17
Surfaces that are touched frequently, such as door handles, toilet seats and taps, should be wiped daily, using a disinfectant,
e.g. alcohol wipes, bleach.17
Soft furnishings that cannot easily be cleaned, e.g. couches and arm chairs, can be covered in a sheet or blanket that
is regularly washed.
Evidence of effectiveness of decolonisation measures
There is mixed evidence of the effectiveness of formal decolonisation regimens in reducing recurrent infections in patients
with persistent carriage of S. aureus. A 2003 Cochrane review of six randomised controlled trials did not find evidence
to support decolonisation of patients with MRSA, with either topical or systemic methods.20 However, further trials have
subsequently been published, some with more positive results.
A recent United States-based study randomised patients with S. aureus colonisation to receive hygiene education only,
education + 2% mupirocin ointment applied inside the nostrils, twice daily for five days; education + mupirocin + chlorhexidine
4% body wash daily; or education + mupirocin + bleach bath daily.21 After one month, the rate of S. aureus nasal colonisation
in patients who received mupirocin (27%), mupirocin + chlorhexidine (26%) and mupirocin + bleach (17%) was approximately
half that in patients who received education alone (46%).21 However, after four months, only the group who received mupirocin
+ bleach had significantly lower rates of S. aureus nasal colonisation (15%) compared to those who received education
alone (50%). The group who received mupirocin + chlorhexidine had a significantly lower rate of recurrent skin infections
after one month (11%) compared to the group who received education alone (26%). However, there was no effect on the rate
of skin infections at either four or six months after the intervention.21
The eradication of S. aureus was thought to be more successful in the group who used mupirocin + bleach compared to
other groups, because soaking in the bleach bath allowed fuller body exposure to the antiseptic and a longer period of
contact, therefore increasing the antimicrobial effect of the intervention.21
As the effect of the initial interventions was not sustained over time it may suggest that decolonisation regimens should
be repeated regularly to successfully eradicate S. aureus. However, there is currently no evidence to support the efficacy
of this approach.
N.B. Mupirocin was used in this study, but is only recommended in New Zealand if colonisation with S. aureus that is
resistant to fusidic acid and sensitive to mupirocin has been confirmed.