Use of polyvinylpyrrolidone in the testing of staphylococci for sensitivity to methicillin and cephradine.

The use of polyvinylpyrrolidone, an inert polymer resembling plasma proteins in its colligative effects, in the testing of micrococcaceae for sensitivity to methicillin and cephradine is described. Generally results are quite comparable with those of conventional methods. The absence of any inhibitory effect of the polymer compared to sodium chloride, and its physiological inertia compared to sucrose, along with its suitability for sterilisation by autoclaving are seen as advantages. It is suggested that the use of this substance may give results which are more applicable to the in vivo situation. This may apply particularly in the case of cephradine.