sentence: MLs inhibit protein synthesis by binding to domain V of 23S rRNA.4 Mutations in domain II or V of 23S rRNA or in L4 and L22 ribosomal proteins have been described to be involved in ML resistance ( MLr ) in other species.5 6 In MP , the MLr in vivo is mainly driven by specific mutations in the V domain of 23S rRNA gene , leading either to a high level resistance profile ( mutations at positions 2063 or 2064 ) or to a low level MLr ( transition at position 2067 or a transversion at position 2617 ) .4 7 – 11 However , although no mutations in domain II could be linked to MLr , mutations in ribosomal proteins L4 and L22 have been found both in vitro4 and in vivo ,9 although their real impact in MLr is still unclear , so further research should be performed.As MP culture is mainly performed in reference centres , MLr determination by broth dilution tests11 is not accessible to most clinical microbiology laboratories .