Novel Tetracycline Resistance Determinant Isolated from an Environmental Strain of Serratia marcescens

Abstract

Resistances to tetracycline and mercury were identified in an environmental strain of Serratia marcescens isolated from a stream highly contaminated with heavy metals. As a step toward addressing the mechanisms of coselection of heavy metal and antibiotic resistances, the tetracycline resistance determinant was cloned in Escherichia coli. Within the cloned 13-kb segment, the tetracycline resistance locus was localized by deletion analysis and transposon mutagenesis. DNA sequence analysis of an 8.0-kb region revealed a novel gene [tetA (41) (41) promoters were analyzed using lacZ fusions, which showed that the expression of both the tetA(41) and tetR(41) genes exhibited TetR(41)-dependent regulation by subinhibitory concentrations of tetracycline. The apparent lack of plasmids in this S. marcescens strain, as well as the presence of metabolic genes adjacent to the tetracycline resistance locus, suggested that the genes were located on the S. marcescens chromosome and may have been acquired by transduction. The cloned Tet 41 determinant did not confer mercury resistance to E. coli, confirming that Tet 41 is a tetracycline-specific efflux pump rather than a multidrug transporter.

Tet 42, a Novel Tetracycline Resistance Determinant Isolated from Deep Terrestrial Subsurface Bacteria

“…2). Similar variations have been seen in other determinants (22). The second operator, while not very similar to the first sequence, matches the second half of the first operator except for 1 base.…”

Mosaic Tetracycline Resistance Genes and Their Flanking Regions in Bifidobacterium thermophilum and Lactobacillus johnsonii

“…New tet genes keep appearing in literature: for example, very recently tet(41) was reported (27). Currently 40 different tetracycline resistance genes (including oxytetracycline-resistant determinants) have been identified (7,22,23).…”

Tetracycline Susceptibility Testing and Resistance Genes in Isolates of Acinetobacter baumannii - Acinetobacter calcoaceticus Complex from a U.S. Military Hospital

“…calcoaceticus complex by amplification of bla OXA-51-like ␤-lactamase genes and by amplified ribosomal DNA restriction analysis (ARDRA) with the restriction enzymes AluI, HinfI, HhaI, RsaI, MboI, and MspI (12,13). The presence of tetracycline resistance genes in 89 singlepatient isolates was determined by PCR amplification for the tetA, tetB, tetH, tetL, tetM, tetA(39), and tetA(41) genes with previously published primer sequences by previously described methods (1,8,11). Data were analyzed according to susceptibility phenotype, PFGE type, and Acinetobacter species as determined by ARDRA.…”