TABLE 2.

Conservative estimate for the number of independent acquisitions of tetracycline resistance among TRGAS isolates

Description of tetracycline-resistant isolatesNo. of representativesNo. of isolatesNo. of distinct STsNo. of independent acquisitions of tetracycline resistance
Singleton isolates, sharing <5 housekeeping alleles with all other strains and/or having different Tet resistance genotypes61616162a
CCs, in which all isolates share at least 5 housekeeping alleles with another member of the complex13b512913
Double-locus variant pairs having different emm types5NAcNA5
TotalNA1129080
  • a Two isolates share the same emm type and ST (emm12 ST36) but have different Tet resistance genes and therefore are scored as separate acquisitions of tetracycline resistance.

  • b All isolates within each of these CCs have tet(M), except for one isolate that lacks both tet(M) and tet(O) (emm58 ST19).

  • c NA, not applicable.