Susceptibility of Ureaplasma urealyticum to ten chemotherapeutic agents

Tetracyclines and erythromycin are the chemotherapeutic agents most often used in the Federal Republic of Germany for eradication of U. urealyticum from the male urogenital tract. Few data on current susceptibility in the FRG are available. Therefore, we investigated the minimal inhibitory concentration (MIC) values of 10 chemotherapeutic agents against 27 isolates from the male urethra and 4 ATCC strains of U. urealyticum by a micro broth dilution method using a modified U-9 medium. The MIC90 values (microgram/ml) of the chemotherapeutic agents tested were as follows: minocycline-0.25, doxycycline-1.0, tetracycline and chlortetracycline-2.0, erythromycin and streptomycin-4.0, chloramphenicol, gentamicin, rosoxacin-8.0, spectinomycin-32.0. According to the blood levels attained in treatment, the chemotherapeutic agents can be divided into three groups based on the MIC90-values, i.e. sensitive: chloramphenicol, doxycycline, minocycline and streptomycin; weakly effective: chlortetracycline, tetracycline, spectinomycin and erythromycin; and resistant: gentamicin and rosoxacin.