To analyse the therapeutic efficacy of various phytotherapeutics and their antimicrobial compounds with regard to strain specificity and dose dependence.
A representative strain collection of 40 uropathogenic bacteria isolated from complicated and uncomplicated urinary tract infection was subjected to various virulence assays (bacterial growth, mannose-sensitive agglutination, and motility) to determine the therapeutic impact of various compounds with antimicrobial activity. We tested proanthocyanidins (PAC), D-mannose, rosemary extract (Canephron®), and isothiocyanates (Angocin®).
D-mannose efficiently blocked the adhesive properties of all type 1 fimbriae-positive isolates in low concentration (0.2%), but showed no bacteriostatic effect. PAC also actively blocked agglutination, but the concentration varied considerably among isolates. Escherichia coli required the highest concentration (10%), while Enterobacter cloacae responded to low concentrations (0.1%). Allyl isothiocyanates not only impaired agglutination in all tested isolates, but also had a dramatic impact on flagella-mediated motility in Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis (p < 0.001). The administration of rosemary extracts revealed a strong bacteriostatic effect in growth assays. All tested strains were strongly inhibited by the addition of 10 μg/ml or 1 μg/ml of purified rosemary extractions with the exception of Serratia marcescens. Morganella morganii responded only to 10 μg/ml.
Phytotherapeutics and small-molecular compounds like mannosides have the potential to become an integral part in a multi-modal treatment concept for the treatment and prevention of urinary tract infections. Their efficiency can be optimised when strain specificities and therapeutic concentrations are taken into account.