CT accounts for the majority of radiation exposure related to medical imaging. Medical professionals should have a working knowledge of the benefits and risks of medical radiation and an understanding of strategies for reducing CT radiation dose.

was a small caecal carcinoma with a 4 cm metastatic deposit in the right lobe of the liver. DISCUSSION Gas gangrene is a condition of rapidly developing and spreading infection mediated by toxins released by the bacteria Clostridium spp. It is most often associated with traumatic injuries. C. perfringens is the commonest species, followed by C. novyi. C. septicum is relatively uncommon, and it is estimated to be the cause of only 1.3% of all clostridial infections. 1-3 C. septicum represents a novel subtype among clostridial species, with several notable differences. It is able to cause devastating tissue necrosis in the absence of prior trauma, 1 3-6 and is able to present distant from the presumed portal of entry resulting in metastatic myonecrosis. 4 5 Clostridial infections are believed to have a greater prevalence among individuals who have malignant disease. 1 4-6 Larson et al, in a series of 241 patients with clostridial infection, found 10% had an associated malignancy. 5 However, when C. septicum infections were considered alone the incidence of associated malignancy was 52.6%. 6 In a further study of patients with C. septicum infection, conducted between 1966 and 1993, 50% had a primary malignancy, 75% of which were colonic, of these 40% were caecal. 5 Few patients presenting with C. septicum infection have a history of prior trauma. 1 4-6 Several papers have suggested that mucosal ulceration of the tumour surface and haematogenous invasion allow a portal of entry for the bacteria, thus explaining the low incidence of antecedent trauma. 7-9 The theory of mucosal ulceration as the portal of entry is supported by the case reported by Abella et al in which a patient with radiation colitis had spontaneous C. septicum gas gangrene. 1 Our case illustrates the fulminant nature of gas gangrene and although it is an uncommon diagnosis, it is essential that the management be initiated early. This should include aggressive resuscitation, early antibiotics, hyperbaric oxygen therapy (although this has never been subjected to a controlled trial and unless it is readily available it would seem to present a potentially fatal delay), and radical surgical debridement.

Nasal application of a nonantibiotic, alcohol-based antiseptic was effective in reducing S aureus and total bacterial carriage, suggesting the usefulness of this approach as a safe, effective, and convenient alternative to antibiotic treatment.

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