Cellulitis is a common bacterial infection of the skin, which is most commonly seen in children and elderly people,
but can affect people of all ages.2 Cellulitis is a common cause of admission to hospital but hospitalisations
are generally preventable if treatment is sought early. Pacific peoples require hospitalisation for cellulitis at a rate
1.5 times that of the total New Zealand population.4
Infection results from the invasion of skin structures by endogenous skin flora or by exogenous pathogenic organisms.
All layers of the skin, fascia and muscle may be involved. The limbs are most often affected but cellulitis can occur
anywhere on the body. Symptoms and signs, e.g. redness, increased warmth, tenderness and swelling, are usually localised
to the affected area but patients can become generally unwell with fevers, chills and shakes due to bacteraemia.3 Complications
include endocarditis, gram-negative sepsis and streptococcal glomerulonephritis.5
The most common infecting organisms are Streptococcus pyogenes and Staphylococcus aureus. Cellulitis
associated with furuncles, carbuncles or abscesses is usually caused by S. aureus.6
Cellulitis is more common in people with:3
- Previous cellulitis
- Venous disease, e.g. gravitational eczema, leg ulceration or lymphoedema
- Current or prior injury, e.g. trauma, surgical wounds, radiotherapy
- Tinea pedis (athlete's foot) in the toes of the affected limb
Pacific adults have higher rates of diabetes and obesity than other New Zealanders,7 which makes them a higher
risk group for cellulitis.
Most patients can be treated with oral antibiotics at home, usually for seven to ten days. However, if there are signs
of systemic illness, extensive cellulitis or poor response to oral antibiotics, treatment with intravenous antibiotics
may be needed.
The first choice oral antibiotic is flucloxacillin. Alternatives include erythromycin, roxithromycin, cefaclor or co-trimoxazole.
Oral doses of flucloxacillin should be taken at least 30 minutes before meals as the presence of food in the stomach reduces
Flucloxacillin is bactericidal with a mode of action similar to that of benzylpenicillin, and is active against penicillinase-producing
and non-penicillinase-producing staphylococci. Flucloxacillin alone is sufficient to treat skin infections that involve
both S. aureus and S. pyogenes. Combination with penicillin is not required as flucloxacillin is active
against the large majority of staphylococcal and streptococcal species that cause cellulitis when given at the appropriate
dose, i.e. 500 mg four times a day for adults.
Flucloxacillin suspension is recommended for children. Although adherence is sometimes an issue with this medicine due
to its taste, parents should be encouraged to persevere with giving flucoxacillin (unless allergic). It is a relatively
safe medicine to use in children, and as it is a narrow spectrum antibiotic, it does not contribute to increasing bacterial
For more current information, see the latest edition of our handbook, "Antibiotics: Choices for common infections", bpacnz.