before large-scale introduction of the new cephalosporins we exposed 5 n. gonorrhoeae strains of different susceptibility to penicillin repeatedly to subinhibitory concentrations of cefotiam , ceftizoxime , rifampicin and penicillin g incorporated into chocolate agar . each time the most resistant representatives of a strain were propagated , on the whole 25 times .
C0030842
penicillin
C0030827
penicillin g