This paper describes research on the levels of endogenous melatonin (MLT) in the blood serum in dogs in different seasons (March, June, September, December) and at different times of day (11:00, 12:00, 23:00, 24:00 and 1:00), using immunoassay method. Blood samples were collected in the diurnal cycle, in consecutive seasons. The conducted studies show that MLT levels undergo clear changes in both the diurnal cycle, as well as in seasonal one in this species.
Introduction: The objective of this study was to describe a pharmacokinetic-pharmacodynamic (PK/PD) approach for determination of a rational dosage of ampicillin (AMP) and depletion of the antibiotic residues in milk after intramammary administration to cows. Material and Methods: The cows came from different farms from the Lublin Province area. They (n = 9) received 5 g of the drug, containing 75 mg of AMP sodium in physiological solution, through a syringe tube by intramammary administration. Following single intramammary administration, the milk samples (5 mL) were collected after 2, 4,6,8,10,24, 36, 48, and 60 h. The liquid chromatography-mass spectrometry analysis was performed on the Agilent 1200 system connected to an AB Sciex API 4000™ mass spectrometer. The pharmacokinetic analysis of the concentrations of the antibiotic in milk was performed using software Phoenix ® WinNonlin ® 6.4. Calculations were made in non-compartmental (slopes, highest, amounts, and moments) and compartmental analysis. Results: The pharmacokinetic characteristics of AMP after intramammary administration indicate rapid elimination of the drug from milk. The mean residence time had a several-fold lower value than the designated elimination half-life and amounts to only 3.4 h. The concentration of the drug in the milk dropped relatively quickly and the process was very dynamic. Conclusion: The conducted research confirms the rationale of using the PK/PD model in order to verify the dosing regimen for other antibiotic groups and various indicators of the applied PK/PD model.
The resistance of 167 pathogenic bacteria of animal origin to quinolones was determined by the disc diffusion method, and by the minimum inhibitory concentration (MIC) test. The highest resistance of Escherichia coli was found to be against nalidixic acid (NA), 49.1% and flumequine (FLU), 38.2%. The sensitivity of the strains were: ciprofloxacin (CIP; 81.8%); enrofloxacin (ENR; 81.8%); norfloxacin (NOR; 80.0%); and pefloxacin (PE; 76.4%). Salmonella spp. showed 100% sensitivity to CIP, ENR, NOR and PE. A high resistance percentage in the cases of: FLU (86.7%); PE (50.0%); and CIP (26.65%) distinguished the Streptococcus spp. The highest percentage sensitivity of Staphylococci was found with three fluoroquinolones: CIP, ENR and NOR, 94.3% each (66 strains). The studies did not indicate that a total cross-resistance might occur between the examined quinolones.
Introduction: The objective of this study was to determine the current profile of bacteria responsible for the infection of the mammary gland and to assess their sensitivity to selected β-lactam antibiotics. Material and Methods: The study was conducted on 119 (n = 119) dairy cows of the Polish Black-White breed aged 4 to 10 years with inflammation of the mammary gland. The cows came from different farms: smallholder farms and large dairy cattle farms in the Lublin and Bialystok Provinces. Before the process of collection of milk samples, the teats were cleaned and immersed in a liquid disinfectant. The first streams were collected into containers which were subsequently utilised. Afterwards, 2-4 mL of milk or secretions was milked into sterile disposable tubes. The milk samples were collected into plastic bottles and kept in a cooler with ice until transportation to the laboratory. Tests of resistance to β-lactam antibiotics were performed by disc diffusion. Results: Contagious and environmental bacteria were isolated from all dairy barns. In the group of contagious bacteria, the presence of typical pathogens responsible for the mammary gland infections, i.e. Staph. aureus, Str. agalactiae, and C. bovis, was detected. A relatively broad group of the isolates was formed by environmental bacteria responsible for inflammation of the mammary gland: Str. dysgalactiae, Str. uberis, Staph. chromogenes, Staph. hyicus, Staph. warneri, and E. coli. Among the environmental organisms, streptococci constituted the largest percentage (23%), followed by staphylococci (13.2%), and E. coli (8.8%). The largest group of infectious pathogens comprised Str. agalactiae (29.6%) and Staph. aureus (20.8%). Conclusion: Our investigation of the current profile of the isolates responsible for mastitis in the Lublin and Bialystok Provinces showed that environmental bacteria are the major cause of the disease. In view of the substantially varying degrees of sensitivity of the microorganisms isolated from cases of mastitis to β-lactam antibiotics, each therapeutic treatment should be preceded by susceptibility testing.
To date, only a few studies on the azithromycin (AZM) pharmacokinetics in ornamental birds have been published. In the current study AZM concentrations in domestic pigeon (Columba livia domestica) plasma samples were analyzed using a validated ultra-high performance liquid chromatography tandem mass spectrometry method. The aim of the current study was to carry out an analysis of the pharmacokinetics and pharmacodynamics after administration of a single oral dose of a sustained-release AZM formulation and to conduct a simulation of treatment based on selected minimal inhibitory values. The study was performed with 12 healthy adult pigeons, both sexes. The pigeons tolerated AZM very well and no adverse effects were observed in any animal during the study. Based on the observed characteristics of the pharmacokinetics/ /pharmacodynamics profiles of AZM in pigeons, it should be noted that 35 mg/kg per os as a single starting dose and 25 mg/kg every 24 h are recommended for treatment of both susceptible and less susceptible pathogens.
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