Decision analysis: a tool for infection control

The medical world would seem to be one of increasing technology and shrinking financial resources. New tests and therapies constantly appear on the market. Most have been examined for efficacy and side effects. The real question is: where does the new test or therapy fit in with all previous products? Decision analysis is a mathematical tool adapted to assess the relative cost-effectiveness of complex diagnostic and therapeutic strategies.     

Factors affecting the toxicity of rotting carcasses containing Clostridium botulinum type E

Mice killed shortly after receiving c. 2000 spores of a type E strain of Clostridium botulinum per os were incubated at one of five chosen temperatures together with bottles of cooked meat medium seeded with a similar inoculum. After incubation the rotting carcasses were homogenized. Sterile membrane filtrates of the homogenates (10%, w/v) and pure cultures were then titrated for toxicity. Some of the main findings were confirmed with two further type E strains. Toxicity produced at 37 degrees C was poor in both carcasses and cultures (200-20,000 mouse intraperitoneal LD/g or ml). It was good in both systems at 30 and 23 degrees C, usually reaching 20,000-200,000 LD/g or ml, and in carcasses occasionally more; at 30 degrees C maximal toxicity was reached more quickly in carcasses than in cultures. Prolonged incubation (36-118 days) at 30 or 23 degrees C resulted in complete loss of toxicity in virtually all carcasses but not in cultures. At 16 degrees C the development of toxicity in carcasses was strikingly greater than in cultures. At 9 degrees C neither system produced more than slight toxicity after prolonged incubation. Trypsinization increased the toxicity of cultures but not usually of carcasses. Unfiltered carcass homogenate (10%, w/v) with maximal intraperitoneal toxicity was harmless for mice by mouth in doses of 0.25 ml. These findings differed in important respects from those made earlier with a type C strain.     

Dietary intake of healthy subjects before and one year after dietary advice

This study was conducted to follow up healthy subjects from a previous study (Warwick & Williams, 1987) in which favourable dietary changes were achieved during 1 week immediately after dietary advice but were accompanied by reduced energy intakes and weight loss. Twenty-one subjects (8m, 13f; 57 per cent of the original group) participated in the follow-up study. Dietary intakes were measured using 7-d weighed records on three occasions: before, immediately after and 1 year after receiving dietary advice. Intakes 1 year after dietary advice continued to show some of the favourable changes observed immediately after the advice but were not accompanied by reduced energy intakes and weight loss. Intakes before, immediately after, and 1 year after dietary advice respectively were: energy, 9.0, 7.8 and 8.9 MJ/d (2150, 1860 and 2120 kcal/d); fat, 36.9, 32.9 and 31.5 per cent of total energy; carbohydrate, 44.2, 47.9 and 49.6 per cent of total energy; dietary fibre, 32, 36 and 36 g/d; sodium, 116, 97 and 110 mmol/d; and Na:K ratio, 1.4, 1.2 and 1.2 mmol. Nutrient densities for fibre and most micronutrients tended to be higher 1 year after dietary advice than before, but were highest immediately after the advice. Nutrient densities for sodium and total sugars did not vary between the 3 study weeks. It was concluded that our healthy subjects adapted their intakes to maintain energy balance while retaining favourable dietary changes for at least 1 year after dietary advice.     

A comparative study of two preservative-free tear substitutes in the management of severe dry eye

Between mid-May and mid-July 1987 we performed a prospective crossover study of two unit-dose preservative-free artificial tear solutions, 1.4% polyvinyl alcohol (Refresh) and 0.1% sodium hyaluronate (Hylorin) in 14 female patients with severe dry eye syndrome. The patients were examined before treatment and after each of two trials with both products. A significant reduction in the mean score for dry-eye-induced keratitis (p = 0.001) and for mucous strands (p = 0.03) was observed following the second of two trials with sodium hyaluronate. A significant reduction in the mean score for burning and irritation was observed with both solutions (p = 0.009). We believe that the elimination of preservatives from artificial tear preparations may substantially reduce the iatrogenic effects of these frequently applied medications.     

Herpes zoster: a consideration in the differential diagnosis of radiculopathy

Herpes zoster probably occurs more often than generally thought. Since it produces a radicular distribution of pain, it should be included in the differential diagnosis of radiculopathy. A case is presented in which evaluating the radicular low back pain before the characteristic rash appears was misleading. Careful history-taking concerning the exact nature of the pain and sensory changes is needed to differentiate between zoster and radiculopathy, if no rash is evident.