Prevalence of Tetracycline Resistance Genes in Oral Bacteria

Abstract

Tetracycline is a broad-spectrum antibiotic used in humans, animals, and aquaculture; therefore, many bacteria from different ecosystems are exposed to this antibiotic. In order to determine the genetic basis for resistance to tetracycline in bacteria from the oral cavity, saliva and dental plaque samples were obtained from 20 healthy adults who had not taken antibiotics during the previous 3 months. The samples were screened for the presence of bacteria resistant to tetracycline, and the tetracycline resistance genes in these isolates were identified by multiplex PCR and DNA sequencing. Tetracycline-resistant bacteria constituted an average of 11% of the total cultivable oral microflora. A representative 105 tetracycline-resistant isolates from the 20 samples were investigated; most of the isolates carried tetracycline resistance genes encoding a ribosomal protection protein. The most common tet gene identified was tet(M), which was found in 79% of all the isolates. The second most common gene identified was tet(W), which was found in 21% of all the isolates, followed by tet(O) and tet(Q) (10.5 and 9.5% of the isolates, respectively) and then tet(S) (2.8% of the isolates). Tetracycline resistance genes encoding an efflux protein were detected in 4.8% of all the tetracycline-resistant isolates; 2.8% of the isolates had tet(L) and 1% carried tet(A) and tet(K) each. The results have shown that a variety of tetracycline resistance genes are present in the oral microflora of healthy adults. This is the first report of tet(W) in oral bacteria and the first report to show that tet(O), tet(Q), tet(A), and tet(S) can be found in some oral species.

Tetracyclines in veterinary medicine and bacterial resistance to them

“…The tet(W) gene has been originally identified in Butyrivibrio fibrisolvens isolate from the bovine rumen, subsequently found in the Clostridium-related human fecal anaerobe bacterium K10 and in human Fusobacterium and Bifidobacterium isolates and recently frequently isolated in bacteria from the human oral cavity (Sco� et al, 1997(Sco� et al, , 2000Villedieu et al, 2003). It was shown to be located on the conjugative transposon TnB1230 .…”

The Butyrivibrio fibrisolvens tet (W) Gene Is Carried on the Novel Conjugative Transposon Tn B1230 , Which Contains Duplicated Nitroreductase Coding Sequences

“…These genes are distinct from previously described ribosome protection genes, with the highest identities being 68% [to Tet(W)] and 76% [to Tet(32)] at the corresponding amino acid level. tet(W) is one of the most widespread tetracycline resistance genes in environmental samples (1,23).Copies of tet(W) found in environmentally and phylogenetically distinct bacterial isolates (2, 20) have remarkable sequence conservation, which argues for the extensive rapid transfer of this gene in nature. Previous work showed that tet(W) could be transferred at high frequencies (10 Ϫ2 to 10 Ϫ5…”

“…These genes are distinct from previously described ribosome protection genes, with the highest identities being 68% [to Tet(W)] and 76% [to Tet(32)] at the corresponding amino acid level. tet(W) is one of the most widespread tetracycline resistance genes in environmental samples (1,23).…”

Distribution of Tetracycline Resistance Gene, tet(M), in Gram-Positive and Gram-Negative Bacteria Isolated from Sediment and Seawater at a Coastal Aquaculture Site in Japan

“…is the most extensively studied antibiotic resistance gene in terms of molecular ecology 9) and has been found among numerous species of Gram-negative and Gram-positive bacteria including not only human pathogens 6,20,22,38) but also bacteria obtained from several terrestrial environments associated with human activity 9) such as in agriculture 33) , groundwater 8) , and daily diets 14,16,26,39) . Tet(M) is often accompanied by mobile elements such as plasmids and transposons, such associations contributing to the wide distribution of this gene in bacterial genera obtained from different environments 9) .…”