The interaction of five anti-pseudomonas antibiotics with both commercial and pseudomonas alginates was studied by investigation of their binding and diffusion characteristics. The two sources of alginate were qualitatively but not quantitatively similar in these respects. Unlike the beta-lactams, gentamicin and tobramycin bound avidly to both sources of alginate and, when the alginate gel to antibiotic ratio was high, the aminoglycosides exhibited diffusion coefficients which were approximately 20% of the beta-lactam values. At much lower ratios of alginate to antibiotic the aminoglycosides caused precipitation in the alginate with apparent disruption of the gel structure, and ultimately penetrated the gel at a faster rate than the beta-lactams. The strong aminoglycoside binding to alginate was reduced, but not eliminated by the presence of physiological concentrations of salts.

Pseudomonas aeruginosa-derived alginate but no other neutral and negatively charged polysaccharides protected mucoid and nonmucoid strains of that organism against ciprofloxacin, gentamicin, ticarcillin, and ceftazidime. Data indicate that alginate has an intrinsic protective effect which is independent of diffusion, charge, or biofilm phenomena.The role of Pseudomonas aeruginosa in lung infections of patients with cystic fibrosis (CF) is well documented (1, 9, 12), but the means by which mucoid strains survive aggressive antibiotic therapy are ill defined. It has been suggested that the alginate may, among other things, directly protect the bacteria against antibiotics by facilitating a biofilm or microcolony mode of growth (7,8) Figure 1 shows the influence of P. aeruginosa alginate concentration on the survival of nonmucoid cells exposed to 0.1 jig of ciprofloxacin per ml. The protection afforded is clearly concentration dependent, with approximately 1, 2, 30, and 60% survivors after 15 min of exposure in the presence of 0, 0.125, 0.25, and 0.50% (wt/vol) alginate, respectively. Qualitatively similar but less-marked effects were observed when autologous alginate was added to washed cells of the mucoid strain (data not shown). The influences of various polymers on survival of the nonmucoid strain exposed to ciprofloxacin and gentamicin are shown in Fig. 2 and 3, respectively; again, qualitatively similar results were obtained with other strains. In each case, only alginate was protective, and that from P. aeruginosa was much more protective than that from seaweed. Controls (data not shown) demonstrated that none of the polymers influenced the growth or survival of any of the strains used, and the order of mixing of polymer, antibiotic, and inoculum had no influence on results. The protective effects of P. aeruginosa alginate on growing cultures of the nonmucoid strain ex-

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This paper describes medication management by elderly patients living in their own homes, and the effects of patient counselling during five domiciliary pharmacy visits on patient compliance and medication management. The 190 subjects who completed the 12‐month study were randomly allocated to either an intervention group (receiving counselling on the correct use and storage of their drugs during five domiciliary visits), a control (V) group (receiving visits but no counselling), or a control (NV) group (having no contact between an initial visit and the end of the study). The patients' drug knowledge, dexterity and cognitive functioning were assessed, and patients in all three groups were well matched at baseline. At each follow‐up visit, patient compliance was measured using pill counts and interviews. After the initial visit, patients in the intervention group demonstrated better compliance, better drug storage practices and a reduced tendency to hoard drugs, and required fewer GP consultations, than patients in either of the control groups. The provision of the domiciliary pharmacy service was effective in detecting drug‐related problems in a potentially high risk patient group. The effectiveness of such a service may be improved by increased transfer of patient information between community pharmacists and general medical practitioners.

Bacillus licheniformis was cultivated in a range of defined media varying in both the nature of the growth-limiting component and the concentration of excess nutrients. The compositions of the media were such as to ensure that the final absorbance (A430) of the culture was the same in each case. Samples taken during the stationary phase were assayed for their content of extracellular serine protease and bacitracin. The nature of the growth-limiting nutrient had a profound effect on the amounts of these products formed while those components which were present in excess also exerted an influence in proportion to their concentration. Thus, for example, a four-fold increase in serine protease production occurred when ammonium replaced glucose as the growth-limiting nutrient. Serine protease and bacitracin production responded differently to these varying cultural conditions suggesting they are subject to separate control mechanisms. The results are discussed in relation to the need for rigorously controlled cultural conditions during physiological studies of this nature.