Genetic basis of erythromycin resistance in oral bacteria

Abstract

We determined the prevalence of erythromycin-resistant bacteria in the oral cavity and identified mef and erm(B) as the most common resistance determinants. In addition, we demonstrate the genetic linkage, on various Tn1545-like conjugative transposons, between erythromycin and tetracycline resistance in a number of isolates.

FIG. 1.

Southern blot hybridization analysis showing a linkage between tet(M), erm(B), int/xis, and aphA-3 genes in the parents and the transconjugants from the filter-mating experiments. The entire genomic DNA was digested with HindIII. BstEII-digested bacteriophage lambda DNA was used as the molecular size marker. Each panel shows the results of probing of the same blot with a different probespecific for tet(M) (A), erm(B) (B), the int/xis region from Tn916 (C), pPPM70 containing aphA-3 (D), and pAM120 (E). The lanes contain genomic DNA, as indicated: lanes 1, E. faecalis JH2/2; lanes 2, B. subtilis BS34A, lanes 3, S. pyogenes 02C1061 containing erm(B) (29); lanes 4, Streptococcus sp. strain E25-3; lanes 5, E. faecalis T1 (transconjugant from the mating of Streptococcus sp. strain E25-3 × E. faecalis JH2/2); lanes 6, Streptococcus sp. strain E31-2; lanes 7, E. faecalis T2 (transconjugant from the mating of Streptococcus sp. strain E31-2 × E. faecalis JH2/2); lanes 8, Streptococcus sp. strain E37-4; lanes 9, E. faecalis T3 (transconjugant from the mating of Streptococcus sp. strain E37-4 × E. faecalis JH2/2); lanes 10, Streptococcus sp. strain E38-2; lanes 11, E. faecalis T4 (transconjugant from the mating of Streptococcus sp. strain E38-2 × E. faecalis JH2/2); lanes 12, Streptococcus sp. strain E23-4; lanes 13, Streptococcus sp. strain E24-2; lanes 14, Streptococcus sp. strain E33-3.