Effect of sodium polyanetholesulfonate and gelatin on the recovery of Gardnerella vaginalis from blood culture media.

Sodium polyanetholesulfonate (SPS) is used as a routine supplement to blood culture media to enhance recovery of microorganisms, but it inhibits the growth of Peptostreptococcus anaerobius, Neisseria meningitidis, Neisseria gonorrhoeae, and Streptobacillus moniliformis. Comparative clinical blood culture studies at the University of Colorado Hospital suggested that SPS also inhibits the growth of Gardnerella vaginalis. We inoculated 16 blood culture isolates of G. vaginalis into 11 blood culture media containing SPS or sodium amylosulfate, with and without gelatin. In the absence of gelatin, only brain heart infusion and thiol broths with SPS supported the growth of more than five strains of G. vaginalis, whereas all media except Bactec 6B and 7C and brucella broths recovered most isolates with SPS and gelatin or with sodium amylosulfate alone. We conclude that SPS inhibits the growth of G. vaginalis in blood culture media but that this inhibition is medium dependent and can be overcome by supplementation of most media with gelatin.