Comparison of the growth inhibitory and bacteriocidal effects of taurolidine and taurultam on a clinical isolate of Escherichia coli

To investigate the mode of action of Taurolin, an antimicrobial preparation, the growth inhibitory and bacteriocidal effects of taurolidine and taurultam solutions on Escherichia coli isolated from a diagnosed urinary tract infection were examined at 37°C. The inhibitory effects of taurolidine solutions were observed to be greater than those of taurultam solutions at comparative concentrations; however, the presence of sublethal concentrations of formaldehyde (methylene glycol) associated with taurolidine was sufficient to account for this. The bacteriocidal activity of taurolidine (2.0% w/v) was greater than that of taurultam (4.5% w/v). Both compounds produced biphasic death rates with dissimilar initial slopes, suggested to be due to the presence of formaldehyde in taurolidine solutions. These observations indicate that the growth inhibitory and bacteriocidal effects of Taurolin solutions are primarily due to taurultam, however, the presence of sublethal concentrations of formaldehyde is significant in the expression of this activity.     

An analogue of the binding polynomial for the case of ligands binding to an aggregating macromolecule

It is known that when a macromolecule exists as a mixture of forms with different molecular weights in equilibrium in dilute solution with ligands then the saturation functions cannot be derived by differentiating a binding polynomial. However, we demonstrate that in such circumstances a saturation function can be expressed in terms of the binding polynomials for each of the polymeric forms of macromolecule and integration of this using the conservation equation affords a function, Q, which is the analogue of the binding polynomial for a non-aggregating system. The existence of Q leads to heterotropic linkage relationships.     

The effects of three non-antibiotic, antimicrobial agents on the surface hydrophobicity of certain micro-organisms evaluated by different methods

The effects of three non-antibiotic, antimicrobial agents (taurolidine, chlorhexidine acetate and providone-iodine) on the surface hydrophobicity of the clinical strains Escherichia coli, Staphylococcus saprophyticus, Staphylococcus epidermidis and Candida albicans were examined. Three recognized techniques for hydrophobicity measurements, Bacterial Adherence to Hydrocarbons (BATH), the Salt Aggregation Test (SAT) and Hydrophobic Interaction Chromatography (HIC) were compared. At concentrations reported to interfere with microbial-epithelial cell adherence, all three agents altered the cell surface hydrophobicity. However, these effects failed to exhibit a uniform relationship. Generally, taurolidine and povidone-iodine treatments decreased the hydrophobicity of the strains examined whereas chlorhexidine acetate effects depended upon the micro-organism treated. Subsequently, the exact contribution of altered cell surface hydrophobicity to the reported microbial anti-adherence effects is unclear. Comparison of the three techniques revealed a better correlation between the results obtained with the BATH test and HIC than the results obtained with the BATH and SAT or SAT and HIC. However, these differences may be due to the inaccuracy associated with the visual assessment of results employed by the SAT.     

Speculating about pyrazines

Of the various types of alerting signals found in nature, odours are the least well understood. The worldwide distribution of pyrazines in plants, insects, terrestrial vertebrates, marine organisms, fungi and bacteria suggests that they are of special significance. We speculate that these molecules served as natural points of convergence in the evolution of widespread alerting signals, which are used for differing but related intraspecific purposes by various species. In aposematic, self-advertising toxic insects and their mimics, for example, pyrazines function as additional warning signals; preliminary data indicates that their odour can potentiate taste aversion learning in rats and the associative learning of immune suppression in mice. The latter suggests that in addition to their alerting properties, pyrazine odours may act as ectohormones which interact with predator physiology.