Tetracyclines recent developments

The practice of incorporating low levels of antibiotics in livestock feeds to promote growth has been particularly controversial. It is feared that this practice will result in development of resistant bacteria in animals, which will in turn be passed on to humans, thus diminishing the effectiveness of antibiotics in treatment of human disease. A petition from the Natural Resources Defense Council to ban such uses of penicillin and tetracyclines recently was denied by the Secretary of Health and Human Services. The controversy therefore is likely to continue. Opinion on the subject is quite polarized, and several points of view are presented in this book. 

Besides the group of psychotropic compounds, we must quote here the antibiotics as drugs where a rapid recent development of techniques can be observed. D.c. polarographic techniques for the determination of chloramphenicol [242], tetracycline [243] and streptomycin [244] are available. The polarographic determination of penicillin G potassium salt is only indirect and is preceded by the introduction of a nitroso group [245]. The synthesis of chloramphenicol comprises the chemical reduc-... 

Other recently developed chemometric approaches include Heuristic evolving latent projections (HELP) [162] which is primarily used for the analysis of qualitative and quantitative data from 2-dimensional data (e.g. HPLC DAD) used for complex mixtures, and HELP lessens the demand on developing complicated separation methods mixed level orthogonal array design (ML-OAD) has been used to optimise the parameters involved in HPLC detection [163]. The LC methods for determining the purity of tetracycline HCl and resolution... 

Sum PE, Sum FW, Projan SJ (1998) Recent developments in tetracycline antibiotics. Curr Pharm Des 4 119-132... 

Still among the most frequently prescribed drugs, the antibiotic tetracyclines have decreased in popularity recently due to development of bacterial resistance in the clinic. The search for improved agents goes on. 

Implications for treatment. It has recently been shown that tetracycline inhibits the development of filarial nematodes from L3 to L4 in vitro (Smith and Rajan, 2000, Experimental Parasitology 95, 265-270). However, chloramphenicol, erythromycin and ciprofloxacin failed to inhibit the... 

UV detection, diode-array detector (DAD) and fluorescence have been the detection techniques used, coupled to HPLC for the analysis of OTC. UV detection is set at 355 nm [49-51], 350 nm [40], or at 353 nm [52], Using the diode array detector [49] offers advantages that the target peak can be identified by its retention time and absorption spectrum. Compared to UV detection, fluorescence detection is generally more specific and is less interfered by other compounds in the sample matrix [51]. A HPLC method with electrochemical detection has also been suggested recently. Zhao et al. [53] described HPLC with a coulometric electrode array system for the analysis of OTC, TC, CTC, DC, and methacycline (MC) in ovine milk. An amper-ometric detection coupled with HPLC was developed by Kazemifard and Moore [54] for the determination of tetracyclines in pharmaceutical formulations. 

Antibiotics. The history of antibiotics is one of remarkable success in saving lives. Penicillin, although discovered earlier, began to be manufactured for sale as a drug in 1942. Tetracycline followed in 1955 and amoxicillin in 1981. These, other variants developed over the years, and some new recent classes of antibiotics treat bacterial infections by killing the bacteria or preventing them from multiplying. In the process, they save lives and speed recovery. Except for some products sold for external use, antibiotics require a prescription. 

Numerous episodes have occurred in which humans have developed drug-resistant nontyphoid Salmonella infections that have been traced to animal sources (23). These bacteria can be transmitted to humans in food or through direct contact with animals. Antimicrobial resistance limits the tlierapeutic options available to veterinarians and physicians for the subset of clinical cases of nontyphoid Salmonella that require treatment. A recent example is a clone of Salmonella typhimurium DT 104 with chromosomally encoded resistance to ampicillin, tetracycline, streptomycin, chloramphenicol and sulfonamides, which has become increasingly common in humans in England and Wales since 1990 (24). Since 1992, only Salmonella enteritidis has accounted for more cases of human salmonellosis than Salmonella typhimurium DT 104 (25, 26). Multiresistant DT 104 has currently emerged in several European countries (27-29) outbreaks have been also reported in the United States in both cattle (30) and humans (31). 

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