Feasibility of screening for penicillinase-producing Neisseria gonorrhoeae from primary culture plates by using a rapid microacidometric test.

We have shown that it is possible to screen for penicillinase-producing Neisseria gonorrhoeae directly from primary culture plates. Experiments involving the cocultivation of four genera of beta-lactamase-positive (beta-lac(+)) bacteria and a beta-lactamase-negative (beta-lac(-)) N. gonorrhoeae on modified Thayer-Martin medium indicated that suppressed or inhibited beta-lac(+) bacteria did not give false-positive results when isolated beta-lac(-) colonies of gonococci were tested. Colonies were assayed for beta-lac production by an adaptation of a microacidometric method in which bacteria could be tested before or after the addition of oxidase reagent.