The activity of the 4 quinolone Ro 23 6240 and the cephalosporins Ro 15 8074 and Ro 19 5247 against penicillin sensitive and resistant gonococci.

We have compared the in-vitro activity of the 4-quinolone Ro 23 6240 and the oral cephalosporins Ro 15 8074 and Ro 19 5247 with that of penicillin, spectinomycin, cefuroxime, ceftriaxone, ciprofloxacin, ofloxacin and norfloxacin against 60 strains of Neisseria gonorrhoeae. MICs 90 against penicillinase producing N. gonorrhoeae (PPNG) and chromosomally-mediated resistant N. gonorrhoeae (CMRNG) respectively were: spectinomycin 16 and 16 mg/l, cefuroxime 0.12 and 1.0 mg/l, ceftriaxone 0.008 and 0.03 mg/l, Ro 15 8074 0.015 and 0.12 mg/l, Ro 19 5247 0.015 and 0.12 mg/l, Ro 23 6240 0.06 and 0.06 mg/l, ciprofloxacin 0.008 and 0.015 mg/l, ofloxacin 0.03 and 0.06 mg/l, norfloxacin 0.06 and 0.12 mg/l. The spectinomycin resistant and spectinomycin-sensitive strains did not differ. All three new agents show good activity against gonococci and warrant further clinical investigation. Ro 23 6240 in common with the other 4-quinolones appears to be as active against gonococcal strains exhibiting non-enzymic chromosomal resistance to penicillin as against PPNG and penicillin-sensitive isolates.