Distribution and diversity of tetracycline resistance genes encoding ribosomal protection proteins in Mekong river sediments in Vietnam

We investigated the distribution and diversity of tetracycline resistance genes encoding ribosomal protection proteins (RPPs) in river and channel sediments of the Mekong Delta in Vietnam. The sediment samples were taken from nine sites in the Hau River in southern Vietnam and from 1 site in a channel in Can Tho City in May 2004 using an Ekman-Birge sediment surface sampler. The RPP genes were amplified using PCR with DNA templates obtained directly from the sediments. The tet(M), tet(S), and tet(W) genes were detected by PCR in most sediment samples. Denaturing gradient gel electrophoresis analysis of these genes and sequencing of the resulting bands showed that tet(S) and tet(W) had only one genotype each, but that tet(M) had at least two, which were tentatively called type 1 and type 2. Type 1 tet(M) was identical to the gene encoded in various plasmids and transposons of gram-positive and gram-negative bacteria, and type 2tet(M) was similar to the gene encoded in Tn1545 of Enterococcus faecalis (99% identity, 170 bp/171 bp). This study showed that various RPP genes were widely distributed in the river and channel sediments of the Mekong Delta.