Oral and Poster Abstracts

pharmacokinetic/pharmacodynamic (PK/PD) parameters. Six
Holstein lactating cows with subclinical mastitis in at least one
mammary quarter were selected. DNF 18% (Advocin ® ,Pfizer Inc,
Argentina) was administered subcutaneously (10 mg/kg single
dose). Blood and quarter milk samples were collected at different
times until 96h after drug administration. Milk and plasma DNF
concentrations were measured by HPLC with fluorescence
detection.The MIC 90 was determined in 51 S. aureus strains to
calculate PK/PD parameters. PK parameters were determined by
non-compartmental analysis. Each mammary quarter was considered
independently (n=24), since our purpose was to compare the
findings in mastitic quarters (n=8) against healthy ones (n=16) and
in quarters of high-producing (HP) cows (n=12) against lowproducing
(LP) cows (n=12). The PK/PD parameters calculated were
AUC 0-24h/MIC 90 (area under the concentration vs time until
24h/MIC for 90% of the isolates), AUC 0-∞/MIC 90 (AUC until
infinity/MIC 90) and T>MIC 90 (time during which the concentrations
exceed the MIC 90).DNF penetration into milk was fast. DNF
concentrations determined in milk (C max=2.7±0.8 µg/mL) were
higher than those found in plasma (C max=1.4±0.2 µg/mL) and milk
bioavailability (F milk) was 4.2.C max in plasma occurred 1.2h postadministration,
while C max in milk occurred 6h post-administration.
T1/2 in milk (8.5h) was longer than T1/2 in plasma (4.4h). The PK
parameters shows that milk concentrations decrease slower than
plasma ones. According to the level of production, DNF was
eliminated slower from quarters of LP cows. Concomitantly, the
mean residence time (MRT) in milk from quarters of LP cows was
longer than the MRT obtained in milk from quarters of HP cows. The
C max and the C max/MIC 90 resulted larger in milk from quarters of LP
cows. According to health status, it was observed that the MRT was
longer in mastitic quarters. The level of production and the quarter
health status could modify the PK and PK/PD parameters of DNF in
milk of lactating cows treated parenterally. Consequently, we
consider that therapeutic protocols should be adjusted according to
susceptibility and the MIC of the bacteria involved and the level of
production of the animal to be treated.
Key words: danofloxacin, pharmacokinetic/pharmacodynamic, milk,
mastitis, cows
406 Epidemiology of Staphyloccoccus aureus Intramammary
Infection in Dairy Cows in Slovenia
O. Podpecan 1 , P. Zrimsek 2 , M. Pate 3 , M. Ocepek 3 , I. Zdovc 3 ,
A. Pengov 3
1
Savinian Veterinary Policlinic, Ruminants, alec, Slovenia
2
Veterinary faculty Ljubljana, Clinic for Reproduction and Horses,
Ljubljana, Slovenia
3
Veterinary faculty Ljubljana, Institute for Microbiology and
Parasitology, Ljubljana, Slovenia
The main objective of the study was to determine factors associated
with epidemiology of S. aureus intrammamary infections in dairy
cows. A total of 763 dairy cows and 2978 udder quarters from 42
herds were included in the study. Lactation number, body condition
score and somatic cell counts (SCC) were calculated. Bacteriological
determination of isolates and genotyping of S. aureus were
performed using the Api-Staph test and pulsed-field gel
electrophoresis (PFGE). Antibiotic resistance rates of S. aureus
isolates were determined using the agar disk diffusion test.
Statistical comparison of the results was performed using Kruskal-
Wallis One Way Analysis of Variance on Ranks, Dunn´s test and
Mann-Whitney-U test. The prevalence of S. aureus intramammary
infection on a herd level was 33.7%. SCC in milk from udder
quarters infected with S. aureus were significantly higher,
irrespective of the lactation number, comparing with bacteriological
negative udder quarters (P