Twenty-five distinct tetracycline-resistant gram-negative bacteria recovered from four Chilean fish farms with no history of recent antibiotic use were examined for the presence of tetracycline resistance (tet) genes. Sixty percent of the isolates carried 1 of the 22 known tet genes examined. The distribution was as follows. The tet(A) gene was found in six isolates. The tet(B) gene was found i...

The present study was done to evaluate the presence of tetracycline resistance genes in Lactococcus garvieae isolated from cultured rainbow trout, West Iran. The isolates were examined for antimicrobial resistance using disc diffusion method. Of the 49 strains tested, 19 were resistant to tetracycline (38.7%), 32 to enrofloxacin (65.3%), 21 to erythromycin (42.8%), 20 to chloramphenicol and tri...

The development and proliferation of antibiotic resistance in pathogenic, commensal, and environmental microorganisms is a major public health concern. The extent to which human activities contribute to the maintenance of environmental reservoirs of antibiotic resistance is poorly understood. In the current study, wastewater treatment plants (WWTPs) were investigated as possible sources of tetr...

Sir, The use of antibiotics in aquaculture production has been associated with the isolation of antibiotic-resistant bacteria in fish as well as pollution of the fish farm environment. Previously, 25 tetracycline-resistant bacteria isolated from four freshwater Chilean salmon farms were characterized. Fifteen of the isolates carried one of seven different tetracycline (tet) genes [tet(A), tet(B...

tet(W) is one of the most abundant tetracycline resistance genes found in bacteria from the mammalian gut and was first identified in the rumen anaerobe Butyrivibrio fibrisolvens 1.230, where it is highly mobile and its transfer is associated with the transposable chromosomal element TnB1230. In order to compare the genetic basis for tet(W) carriage in different bacteria, we studied sequences f...

Worldwide tetracycline resistance (Tc) is increasing dramatically, causing serious environmental and health problems. A total of 201 samples were collected from chicken intestine, human feces and treated sewage effluent (TSE). One hundred and eighteen Escherichia coli strains were isolated and identified using MALDI-Biotyper. Single and multiplex PCR were used to screen isolates for 14 tet gene...

Tigecycline is a glycylcycline antibiotic active against multidrug-resistant bacterial pathogens. The objectives of our study were to examine the potential of the Tet(A), Tet(K), Tet(M), and Tet(X) tetracycline resistance proteins to acquire mutations causing tigecycline resistance and to determine how this affects resistance to earlier classes of tetracyclines. Mutations in all four tet genes ...

The tet(M) gene encodes a protein which is related to tetracycline ribosomal protection, one of the mechanisms of tetracycline resistance. A tet(M) gene that is 100% homologous to the tet(M) gene of Staphylococcus aureus has been found in a clinical isolate of Acinetobacter baumannii, which also carries the tet(A) gene encoding a tetracycline efflux pump.

MICs of tetracyclines were determined for 86 human Bifidobacterium isolates and three environmental strains. The tet(O) gene was found to be absent in these isolates. tet(W) and tet(M) were found in 26 and 7%, respectively, of the Bifidobacterium isolates, and one isolate contained both genes. Chromosomal DNA hybridization showed that there was one chromosomal copy of tet(W) and/or tet(M).

The DNA sequences upstream of the tet(O) and tet(M) open reading frames (ORFs) (ca. 300 bp) were found to share a higher degree of homology than those of the tet(O) and tet(M) ORFs themselves. A transcription initiation site for tet(O) was located by primer extension analysis. Campylobacter coli was found to use a promoter sequence different from that used by Escherichia coli. The sequence upst...