TABLE 2

In vitro synergistic effect of clarithromycin and vancomycin against two M. abscessus type strains with inducible clarithromycin resistance under induced conditions

StrainDayMIC (μM) of:FICIa
CLR aloneVAN aloneCLR in combinationVAN in combination
Preincubation induction assay
    M. abscessus subsp. abscessus ATCC 199773>20012.50.393.12<0.25
    M. abscessus subsp. bolletii CCUG 50184T3>2006.253.121.56<0.25
Standard inducible resistance assay
    M. abscessus subsp. abscessus ATCC 1997736.25250.393.120.19
7251000.3912.50.14
14>20010012.56.25<0.13
    M. abscessus subsp. bolletii CCUG 50184T312.512.50.781.560.19
725501.563.120.12
14>20050251.56<0.16
  • a A less than symbol (<) preceding a FICI score indicates that an MIC of the drug alone was higher than the greatest concentration tested, which was used in FICI calculation.