PCR detection of oxytetracycline resistance genes otr(A) and otr(B) in tetracycline-resistant streptomycete isolates from diverse habitats.

A range of European habitats was screened by PCR for detection of the oxytetracycline resistance genes otr(A) and otr(B), found in the oxytetracycline-producing strain Streptomyces rimosus. Primers were developed to detect these otr genes in tetracycline-resistant (Tc(R)) streptomycete isolates from environmental samples. Samples were obtained from bulk and rhizosphere soil, manure, activated sludge and seawater.

Phylogeny of efflux-mediated tetracycline resistance genes and related proteins revisited.

A SRS search in the GenBank/EMBL databases for entire genes encoding efflux-mediated resistance allocated to a recognized tetracycline determinant revealed the existence of at least 87 genes. DNA-based and protein sequence analyses of representatives from the different efflux-mediated tetracycline determinant groups were performed and allowed us to propose a revision of the current grouping on the basis of our new evolutionary trees. On the other hand, similarity, topology, and hydropathy analyses of some representatives from 12-transmembrane segments (TMS) and 14-TMS proteins lead us to perform meaningful sequence alignments of recognized or putative 12-TMS and 14-TMS proteins truncated to their first 200 amino acids (alpha-domain of the protein).