The emergence of bacterial resistance to tetracyclines mirrors the situation with most antimicrobials currently in use. These drugs are relatively inexpensive, have a broad-spectrum of activity, and have been extensively used in the prophylaxis and therapy of human and animal infections and as animal growth promoters. The selection pressures exerted by the use of tetracyclines in these various environments have resulted in the emergence of resistant organisms. The first tetracycline resistance R factors were identified over 40 years ago in Japan.[1] Since then, tetracycline resistance genes have spread in both gram-negative and gram-positive genera, primarily by conjugal transfer of plasmids and/or transposons. The dramatic increase in the number of species and genera that have acquired tetracycline resistance since the 1950s has led to a reduction in the efficacy and use of current tetracycline therapy for many diseases.

As PCR and microarray technology become less expensive and more automated, it will be easier for more laboratories to look at the genotypes of antibiotic-resistant bacteria. However, this information will need to be shown to be clinically relevant and cost-effective. This scenario assumes that clinical laboratories will continue to culture bacterial samples, although there are some suggestions that nonculture techniques such as PCR could replace standardized culture methods in the coming years because these methods can be less costly. Regardless of where culture methods go at this time, it is inadvisable to look for specific tetracycline resistance genes in direct samples other then those taken from normally sterile sites because many commensal bacteria carry the same resistance genes as do the pathogens.[1]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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