Antibiotics, detection fluoroquinolones

Snitkoff et al. [75] reported the development of an EIA for the detection of ciprofloxacin in serum, which was sensitive at picogram per milliliter levels of the antibiotic and no cross-reaction with its metabolites was observed. Gobbo et al. [118] recently described the production of PAb for ciprofloxacin with the aim of detecting fluoroquinolones in Brazilian livestock. On the other hand, Bucknall et al. [77] produced antibodies for quinolones and fluoroquinolones with the aim of developing both generic and specific immunoassays. ELISAs for ciprofloxacin, enrofloxacin, flumequine, and nalidixic acid were developed with sensitivity values around 4 pg kg 1 (on both the generic and specific assays) in bovine milk and ovine kidney. 

Macrolide antibiotics (clarithromycin, dehydroerythromycin, etc.) and sulfonamides (sulfamethoxazole, sulfadimethoxine, sulfamethazine, and sulfathi-azole) are the most prevalent antibiotics found in the environment with levels around a few micrograms per liter, whereas fluoroquinolones, tetracyclines, and penicillins have been detected in fewer cases and usually at low concentrations (nanograms per liter) [3,20,23,72]. This result is not surprising, since penicillins are easily hydrolyzed and tetracyclines readily precipitate with cations such as calcium and are accumulated in sewage sludge or sediments. Several reviews have reported the environmental occurrence of different antibiotics in aquatic and soil compartments. Some of these data are detailed in Table 1. 

Seifrtova M, Pena A, Lino CM et al (2008) Determination of fluoroquinolone antibiotics in hospital and municipal wastewaters in Coimbra by liquid chromatography with a monolithic column and fluorescence detection. Anal Bioanal Chem 391 799-805... 

Nakata H, Kannan K, Jones PD (2005) Determination of fluoroquinolone antibiotics in wastewater effluents by liquid chromatography and fluorescence detection. Chemosphere 58 759-766... 

However, recent investigations on the effect of the tissue matrix on the detection limits attained by this test have indicated that ceftiofur, sulfonamides, streptomycin, and some macrolide antibiotics cannot be detected in intact meat with the plates and the bacterial strains prescribed in the European four-plate test (81, 82). Two plates of this system were not found suitable for screening sulfamethazine or streptomycin at levels far above the MRL the third plate detected tetracyclines and -lactams up to the MRL levels whereas the fourth was sensitive to -lactams and some but not all macrolides. Detection, on the other hand, of the fluoroquinolones enrofloxacin and ciprofloxacin could only be made possible by an additional Escherichia coli plate not included in the four-plate test. 

In recent years antibiotics residues have accumulated in different environmental compartments. Fluoroquinolone antibiotics are strongly adsorbed by soil, and therefore their extraction requires exhaustive procedures, leading to complex extracts due to coextraction. Despite this the authors succeeded in selectively detecting the fluoroquinolones from crude soil extracts directly injected onto an MIP HPLC column and using UV detection [Fig. 2 (Fig. 6 of the original)]. Recoveries close to 100% were obtained for five fluoroquinolones. The analysis time was only a few minutes, so this method was found suitable for screening soil samples for the presence of fluoroquinolones. The individual fluoroquinolones were not resolved on the column. 

Pinacho, D.G., F. Sanchez-Baeza, and M.P. Marco. 2009. Development of a class selective indirect competitive enzyme-linked immunosorbent assay (ELISA) for detection of fluoroquinolone antibiotics. J. Agric. Food Chem. submitted. 

Chen, Y. and Schwack, W. 2013, Planar chromatography mediated screening of tetracycline and fluoroquinolone antibiotics in milk by fluorescence and mass selective detection, J. Chromatogr. A, 1312 143—151. 

Tetracyclines and fluoroquinolones form strong complexes with bivalent ions like calcium. Therefore, EDTA was added during milk extraction and EDTA-modified silica gel was selected as a layer material offering the best separation (free of tailing) of the target compounds and a signihcant fluorescence enhancement effect for a low limit of detection. The selected solvent system provided the complete separation of the seven antibiotics (Eigure 10.4), when a 10% EDTA solution for the layer modification was verified as optimal for the best separation of TCs and EQs [6]. 

The use of l-ethyl-3-methylimidazolium tetrafluoroborate as mobile phase additive has been evaluated for the analysis by HPLC with fluorescence detection for seven basic fluoroquinolone antibiotics, i.e., fleroxacin, ciprofloxacin, lomefloxacin, danofloxac-... 

Some of the other applications of in vivo F MRS to the study of fluorinated drugs have included the study of fluorinated antibiotics and antifungal agents in animals and humans. Orally administered fler-oxacin (a fluoroquinolone antibiotic agent) could be detected in the liver and calf muscle by in vivo F MRS. Furthermore, its washout and metabolism were studied over a 24-hour period. There are important implications of this work, and it will in future be possible to ensure that drugs reach their target site in appropriate concentrations. 

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