Medium-dependent inhibition of Peptostreptococcus anaerobius by sodium polyanetholsulfonate in blood culture media.

Of 13 species of anaerobic cocci, Peptostreptococcus anaerobius was the only species tested that was sensitive to 0.1% sodium polyanetholsulfonate (SPS). However, the sensitivity of P. anaerobius to SPS varied according to the media in which the cultures were grown. In supplemented peptone (B-D) and brain heart infusion media, most strain of P. anaerobius were not inhibited by SPS. Gelatin and proteose peptone were the medium components which were protective. The minimal inhibitory concentration of SPS for P. anaerobius was approximately 60-fold higher in media. However, the concentration of SPS required to neutralize the bactericidal properties of human serum was only four fold higher in media containing geltain. In a commerical medium containing SPS (0.03%) and gelatin (1.2%), SPS-sensitive strains of P. anaerobius were not inhibited by SPS, and the bactericdal action of human blood on Escherichia coli C and Serratia marcescens SM 29 was eliminated.