IN VITRO ACTIVITY OF THE NEW KETOLIDE TELITHROMYCIN AND OTHER ANTIBIOTICS AGAINST STREPTOCOCCUS PNEUMONIAE IN BELGIUM.

Abstract

In Belgium more than 17 % of the invasive pneumococci are not susceptible to penicillin, and more than 38 % not to macrolides. The most prevalent mechanism of macrolide resistance in Europe is modification of the drug target site leading to cross-resistance to lincosamides and group B streptogramines (MLS_B resistance).

Telithromycin is the first antibiotic of the family of ketolides, which differ from erythromycin by having a 3-keto group instead of the neutral sugar L-cladinose.

We tested the susceptibility of 637 pneumococci, recently isolated from patients in Belgium, to telithromycin and five other antibiotics. Data generated by this study show that telithromycin inhibits 98.4 % of pneumococci at a breakpoint concentration of 1 mg/L in spite of a high percentage ( >30 %) of strains with the MLS_B constitutive type of resistance. Susceptibilities to the five comparator drugs were : penicillin (81.8 %), tetracycline (67.0 %), levofloxacin (98.9 %), erythromycin (61.5 %) and clindamycin (66.6 %). Consequently telithromycin looks to have considerable potential for the empiric treatment of community-acquired respiratory tract infections.

Keywords:

• telithromycin
• pneumococci
• cross-resistance