Analysis of fluoroquinolones in dusts from intensive livestock farming and the co-occurrence of fluoroquinolone-resistant Escherichia coli.

Fluoroquinolones are important therapeutics in human and veterinary medicine. This study aimed to retrospectively analyse sedimentation dusts from intensive-livestock-farming barns for fluoroquinolones and investigate the association between resistant Escherichia coli and the detected drugs. Sedimentation-dust samples (n = 125) collected (1980-2009) at 14 barns of unknown-treatment status were analysed by HPLC and tandem-mass spectroscopy to detect enrofloxacin, ciprofloxacin, marbofloxacin, and difloxacin. Recent microbiological data were included to investigate the relationship between fluoroquinolone presence and fluoroquinolone-resistant E. coli. Fifty-nine dust samples (47%) from seven barns contained fluoroquinolone residues. Up to three different fluoroquinolones were detected in pig and broiler barns. Fluoroquinolone concentrations ranged from 10-pg/mg to 46-ng/mg dust. Fluoroquinolone-resistant E. coli were isolated from four barns. Of all the dust samples, 22% contained non-susceptible isolates. Non-susceptible isolate presence in the dust was significantly associated (p = 0.0283) with detecting the drugs, while drug detection increased the odds (4-fold) of finding non-susceptible E. coli (odds ratio = 3.9877, 95% CI: 1.2854-12.3712). This retrospective study shows that fluoroquinolone usage leads to dust contamination. We conclude that farmers and animals inhale/swallow fluoroquinolones and fluoroquinolone-resistant bacteria due to drug application. Furthermore, uncontrolled drug emissions via air exhausted from the barns can be assumed.

Determination of fluoroquinolones in chicken feces - a new liquid-liquid extraction method combined with LC-MS/MS.

The application of antibiotics including fluoroquinolones to farming animals is widespread and may lead to the development of antibiotic resistance and other environmental effects. To calculate environmental loads and for a proper risk assessment it is necessary to determine the antibiotic concentration in feces. Therefore, a new liquid-liquid extraction method combined with HPLC-MS/MS for the detection of marbofloxacin, ciprofloxacin, enrofloxacin and difloxacin in chicken feces was developed. Recoveries ranged from 51.0% to 83.5%. LOQs were between 0.10 and 1.09µg/kg. Feces of chickens treated with an enrofloxacin dosage of 10mg/kg bodyweight revealed maximum enrofloxacin and ciprofloxacin concentrations of 61.3 and 18.8mg/kg. Both antibiotics could be detected in feces up to two days after the last application in notable amounts (∼1mg/kg). Thus, feces of recently medicated chickens should not be used as a fertilizer without any further processing.

Comparison of different solid-phase extraction materials for the determination of fluoroquinolones in chicken plasma by LC-MS/MS.

Fluoroquinolones are synthetic antibiotics which are frequently used in veterinary medicine e.g. for the treatment of poultry. Their specific importance is based on the fact that they are regarded as antibiotics of last resort because of their broad spectrum of action against Gram-negative and -positive bacteria. Here, a new and sensitive method for the simultaneous determination of four fluoroquinolones (marbofloxacin, ciprofloxacin, enrofloxacin and difloxacin) in chicken plasma by LC-MS/MS was developed. Solid-phase extraction was chosen for sample preparation because a selective sample clean-up is combined with an effective extraction. Various solid-phase extraction materials including polymer-based reversed-phase, silica-based reversed-phase and mixed-mode sorbents were compared. Selection criteria were analyte recovery, sample extract purity and economical aspects (analysis time and elution solvent volume). Best recoveries and minimized elution solvent volumes were achieved using polymeric reversed-phase cartridges. However, post-column infusion experiments revealed that the analysis is influenced by co-eluting matrix components. Hence, a combination of a mixed-mode anion-exchange cartridge and a mixed-mode cation-exchange cartridge was used as final extraction method. This method yield slightly lower analyte recoveries compared to polymeric-reversed-phase cartridges but exhibit no matrix effects. Recoveries of spiked chicken plasma ranged from 61.9% to 84.8% with an inter-day precision of generally less than 12%. LODs are between 0.03 and 0.05µg/L; LOQs are between 0.08 and 0.16µg/L. Maximum plasma concentrations of chickens medicated with an enrofloxacin dosage of 3mg/kg bodyweight were 38.9µg/L for enrofloxacin and 3.3µg/L for its main metabolite ciprofloxacin.

Determination of drug residues in urine of dogs receiving anti-cancer chemotherapy by liquid chromatography-electrospray ionization- tandem mass spectrometry: is there an environmental or occupational risk?

Cytotoxic drugs, previously used only in human medicine, are increasingly utilized for cancer treatment in veterinary practice. We developed and validated a liquid chromatography (LC)-electrospray ionization-tandem mass spectrometry (MS-MS) method to determine vincristine, vinblastine, cyclophosphamide, and doxorubicin in canine urine. Sample pretreatment consisted of liquid-liquid extraction, and LC separation was carried out on an RP C(18) column employing a 0.5% formic acid/methanol gradient system. The analytes were detected in positive ion mode using the MS-MS scan mode. The mean recoveries in six different urine samples were between 64.2% and 86.9%. Limits of quantitation were 0.5 microg/L for vincristine and vinblastine, 1 microg/L for cyclophosphamide, and 5 microg/L for doxorubicin; limits of detection were approximately 0.25 microg/L for vincristine, vinblastine, and cyclophosphamide and 0.5 microg/L for doxorubicin. It could be demonstrated that all investigated drugs are found in urine of dogs undergoing chemotherapy. In samples from day 1 after chemotherapy, as much as 63 microg/L vincristine, 111 microg/L vinblastine, and 762 microg/L doxorubicin could be detected. Cyclophosphamide showed only minor concentrations on day 1, but up to 2583 microg/L could be found directly after chemotherapy. These initial data show that there might be a potential contamination risk when administering cytotoxics in veterinary medicine.

Degradation and elimination of various sulfonamides during anaerobic fermentation: a promising step on the way to sustainable pharmacy?

Antibiotics, most notably sulfonamides and tetracyclines, are frequently used veterinary pharmaceuticals in animal husbandry. A new field of application for animal manure is in biogas plants for generating environmentally friendly energy. As a result, antibiotics contained in manure may still reach the environment as fermentation residues are also used on agricultural fields as fertilizers. Therefore, in fermentation tests seven sulfonamides and trimethoprim were investigated regarding their elimination behavior during a five-week fermentation process. Sulfadiazine, sulfamerazine, sulfamethoxazole, sulfadimethoxine, and trimethoprim were nearly completely eliminated while sulfathiazole, sulfamethazine, and sulfamethoxypyridazine showed persistence. For sulfadiazine it was possible by means of mass spectrometry to identify and partly quantify a metabolite, emerging from a hydroxylation at the pyrimidine ring, 4-OH-sulfadiazine. Furthermore, a microbial inhibition test showed a substantial reduction in the antimicrobial activity of the metabolite compared to the parent compound. Thus, the fermentation process may be an efficientwayto reduce the load of selected veterinary antibiotics finding their way into the environment Degradable drugs such as sulfadiazine may therefore, at least in the aspect of residual antibiotic activity of metabolites, be considered as environmentally friendly drugs.