MLSB resistance

Both azithromycin and clarithromycin have been used for various bacterial infections for a number of years. Within the last decade, resistance has emerged to a range of antibacterials, including the macrolides, arising from methylation of an adenine in the 23S ribo-somal RNA target site, which prevents binding (146). The invention of the ketolides [e.g., telithromycin (115)] overcomes MLSb resistance by removing the L-cladinose moiety at position 3 the exposed hydroxyl is also oxi-... 

Macrolide, lincosamide and streptogramin B resistance (MLSb phenotype) can be linked to specific nucleotide changes within the 23 S rRNA of the large ribosomal subunit, mainly at position A2058 or neighbouring bases (E. coli numbering). This is the... 

Of 302 clinical isolates of S. pyogenes from Portugal, 108 were resistant to erythromycin, and 86 also had a constitutive resistance to clindamycin (MLSB phenotype) (59). Four isolates had a phenotype characterized by low-level erythromycin resistance and high-level chn-damycin resistance. In another European study of 286 S. pneumoniae strains, 7% were resistant to penicUhn, and 35% were also resistant to clindamycin (60). Of 3205 group A streptococcal strains from Canada, only 18 and 2 strains respectively showed inducible and constitutive resistance to clindamycin (61). Among 180 strains of the Streptococcus milleri group isolated in Spain, 17% were resistant to clindamycin (62). 

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