Inhibition of nonspecific streptococcal coagglutination reactions

Description of 14 new capsular types of Streptococcus suis

Fourteen new capsular types of Streptococcus suis (types 9 to 22) are described. All reference strains are morphologically and biochemically similar to types previously described. Reference strain types 9 to 13, 15, 16, and 22 were isolated from diseased pigs, whereas types 17 to 19 and 21 came from clinically healthy pigs; type 14 was isolated from a human case of meningitis, and type 20 was isolated from a diseased calf. The group T streptococcus of de Moor has been included in the typing system as type 15. Two-way cross-reactions between types 6 and 16 and a one-way cross-reaction between types 2 and 22 have been demonstrated. In addition, several cross-reactions probably not due to capsular material were detected among different types by using the coagglutination test. This test should not be used alone; weak or multiple positive reactions must be confirmed by the capsular reaction test or the capillary precipitation test.

Streptococcus faecalis susceptibility to amiloride depends on medium pH

Amiloride is one of the major molecular probes in basic and applied investigations on the physiology of cation transport in animal cells. In these cells the drug also exerts growth inhibitory activity. Recently, we discovered that amiloride causes growth inhibition also on bacterial cells. In this paper we report that medium pH influences amiloride activity on Streptococcus faecalis. The lowering of external pH causes a drop in the susceptibility of this bacterium to amiloride up to an almost complete resistance. This finding, constitutes a novel aspect of the in vitro experimental pharmacology of this diuretic potentially useful also in clinical pharmacology and in animal cell investigations.

In vitro antistreptococcal activity of the potassium-sparing diuretics amiloride and triamterene

The ionophore antimicrobial agents provide evidence that perturbations of the electrolyte balance of bacterial cells exert a growth-inhibitory activity. Several drugs acting on animal cell membranes have also been shown to be active on bacterial cells. In this paper, we report preliminary susceptibility studies showing that the class of potassium-sparing diuretics acting directly on monovalent cation fluxes on animal cells possesses a selective growth-inhibitory activity on hemolytic streptococci.