Detection of L-Forms of Neisseria gonorrhoeae in Pure and Mixed Culture Suspensions by an Enzyme Immunoassay

An enzyme immunoassay (EIA) (Gonozyme™, Abbott Labo-ratories, Chicago, IL) was evaluated for its ability to detect In-forms of Neisseria gonorrhoeae in pure and mixed culture suspensions. A total of IS L-form strains that were induced from fresh clinical isolates of N. gonorrhoeae on an L-form medium were tested by EIA at antigen levels equivalent to those found in 2 × 105, 3 × 104, and 2 × 103 parental cells per milliliter. The results showed the sensitivity of the EIA for L-forms and parental cells to be the same, exhibiting positive results in all pure culture suspensions of parental cells at 2 × 105 and 3 × 104 cells per milliliter and their corresponding L-form preparations. At 2 × 103 cells per milliliter, three parental and two of their respective L-form preparations yielded positive EIA results. Incorporation of a mixture of heterologous organisms that can be found in the normal human genital flora, each at a concentration of 1 × 107 cells per milliliter into the L-form preparations, did not affect the sensitivity of the EIA for detection of L-forms. The results of the present study indicate that the EIA is an equally sensitive method for detecting gonococcal L-forms and parental cells. A further study, however, is needed to ascertain its usefulness under actual clinical conditions.