Preventing cellulitis: where next?

Abstract

Cellulitis of the lower leg is a moderately common and unpleasant condition associated with painful erythema and swelling, in some cases high fever, and very rarely shock and cardiovascular collapse. It has been associated with β‐haemolytic streptococcal infection, with group A and group G streptococci being most often implicated. However, one of the problems with the diagnosis is that it is almost entirely reliant on clinical findings. Bacterial culture itself is seldom useful, as unless there is blood culture‐positive septicaemia, swabs from the skin surface are only rarely positive. One study of the success of blood culture as a means of establishing the diagnosis of cellulitis found only a handful of positive cases – 2% out of a large sample of 710 cultures taken.1 Even the most recent molecular diagnostic methods appear to be no better than culture, although occasionally specific putative entry sites such as the toe webs can be positive for streptococcal DNA.2 Submitting aspirates from the affected area either to culture or molecular probing, for example with 16S rRNA DNA, did not improve the diagnostic yield, and the only positive diagnostic samples in one comparative study were staphylococci.3 In cellulitis at sites other than the legs, the yield of positive microbiological clues is often higher, but even so, in a study of orbital cellulitis, only 30% of over 90 cases sampled yielded evidence of a microbe.4