Volume 18, Number 9—September 2012
Dispatch
Antimicrobial Drug Use and Macrolide-Resistant Streptococcus pyogenes, Belgium
Table
Characteristics of macrolide-resistant Streptococcus pyogenes used in competition experiments and relative fitness* of the erm(A)-emm77 geno-emm-type against competitor strains, Belgium, 1999–2009
Geno-emm-type | Macrolide MIC, mg/L |
Relative fitness (SD)† |
p value, t test | |||
---|---|---|---|---|---|---|
Erythromycin | Clindamycin | erm(A)-emm77 | Competitor | |||
erm(A)-emm77 | 2 | 0.125 | ND | ND | ND | |
erm(B)-emm28 | >512 | >512 | 1.03 (0.09) | 0.98 (0.09) | 0.662 | |
erm(B)-emm22 | >512 | >512 | 1.27 (0.15) | 0.79 (0.09) | 0.080 | |
erm(B)-emm11 | >512 | 256 | 2.12 (0.28) | 0.48 (0.06) | 0.013 | |
mef(A)-emm12 | 8 | 0.125 | 1.29 (0.18) | 0.78 (0.11) | 0.105 | |
mef(A)-emm4 | 8 | <0.03 | 1.55 (0.15) | 0.65 (0.06) | 0.047 | |
mef(A)-emm1 | 16 | 0.5 | 1.01 (0.05) | 1.00 (0.06) | 0.934 |
*The ability of the bacteria to survive and reproduce. ND, no data.
†Average of duplicate experiments.