Reply to: "Letter to the Editor: concerning an article comparing the efficacy of local and systemic treatment of clinical mastitis".

My publication (Soback et al., 1990) was criticized in a recent Letter to the Editor (Pyörälä, 2005). Pyörälä claimed that the paper should not be referenced in the report of Sérieys et al. (2005) or, for that matter, anywhere. However, Pyörälä fails to describe the alleged errors in the Soback et al. (1990) paper. I find the Soback et al. (1990) paper, for which I am the principal and corresponding author, basically flawless with considerable scientific merit. Pyörälä goes on to claim that the authors themselves have refuted the study, which is inconsistent with the truth. Pyörälä also disregarded our subsequent and only published results on systemic norfloxacin dry-cow treatment (Saran et al., 1995), which did not refute the Soback et al. (1990) paper. By 1995, <3% of Israeli cows had subclinical Staphylococcus aureus mastitis, and the research was abandoned as logistically impractical. I also disagree with Pyörälä’s criticism concerning the report of Sérieys et al. (2005), which I found a worthy study. Correlation between susceptibility testing and mastitis therapy outcome has been shown only for very few compounds. Susceptibility testing cannot, therefore, be considered a prerequisite for successful treatment, especially with the antibiotics used in the Sérieys et al. (2005) study. The β-lactamase production was emphasized by Pyörälä, and two reports were quoted to support the criticism. The study by Sol et al. (2000) contradicts Pyörälä’s suggestion. The antibiotics used in that study were not β-lactamase susceptible, and no resistance was encountered rendering β-lactamase production irrelevant. Not surprisingly, the βlactamase production in the study correlated with more chronic infection. Systemically treated cows were excluded from this study.