Abstract
Summary and Conclusions
Meningococci are readily killed by penicillin in nutrient broth at 37°. This meningococcidal action is markedly increased by fresh serum of man, rabbit, guinea pig and mouse, due to a heat-labile component, presumably complement. The meningococcus therefore is an unsuitable microorganism on which to test human sera for their content of penicillin by the bacteriostatic method commonly employed. The presence of inactivated serum, however, frequently reduces the activity of penicillin on meningococci in broth.
Penicillin fails to kill meningococci in a non-nutrient medium (gelatin-Locke's solution) at 37° and in nutrient broth at ice box temperature, two conditions unfavorable for their growth. These findings lend support to the notion, already expressed by others, that penicillin acts on bacteria only in an environment which promotes their multiplication.
Penicillin causes a certain degree of lysis of meningococci actively growing in broth.
Meningococci in broth containing concentrations of penicillin just below the level of bacteriostasis develop enlarged forms which suggest an inability to complete the normal process of fission.
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