Letter to the Editors regarding the Scientific paper by Gonzalez, Moreno, Fumuso et al.,

SANCHEZ BRUNI S.

JOURNAL OF VETERINARY PHARMACOLOGY AND THERAPEUTICS

WILEY-BLACKWELL PUBLISHING, INC

Año: 2010 p. 416 - 417

0140-7783

Reply Letter to the Editor Regarding the Letter to the Editor signed by Marilyn Martinez and Ted Whittem, in which they expressed concern about a paragraph in the discussion of a recently published paper by Gonzalez, C. et al. 2010. Their contention is that this paragraph misinterprets the previous report by Martinez et al. 2006. The authors wish to clarify that our discussion was, in fact, written in the context of comments made in a later article (Martinez et al., 2006; page 20, 4th paragraph) and not the one cited (i.e. Martinez et al., 2004). We believe that, whilst the interpretation regarding the global PK/PD relationship for fluoroquinolones (FQ) is correct, the wording of the mentioned paragraph could have been better. However, we also believe that our discussion does not affect either the quality or relevance of the reported data. In the article published by Martinez et al., 2006, the authors clearly stated that: “….FQ are highly effective in the presence of high Cmax/MIC values, exceptions to this rule have been observed. For example in the case of Bacillus anthracis…..”. Later, they also referenced other authors who had demonstrated in vitro, (for gemifloxacin in a S. pnumoniae model), that “…  time to kill 99% of inoculums depends on Cmax/AUC, but the ability of to maintain this decrease is related to AUC/MIC (based on area under bacterial killing curve) (MacGowan et al., 2000, 2001). Those authors concluded that “If the duration of time between doses is extended beyond 24 h (as was tested by gemifloxacin), effectiveness may also depend upon the duration of time that drug concentrations exceed the MIC (T>MIC) (MacGowan et al. 2001)”. Although, other more recent examples are also available, we wish to make it absolutely clear that our statement (i.e. “FQ appear to exhibit…”) was not intended as a dogmatic assertion concerning the global concept of PK/PD relationships for FQ. Rather, it was intended to point out that under certain situations, the duration of exposure to the fluoroquinolone can also have an important role in determining the characteristics of its antimicrobial activity. In conclusion, we can confirm that we entirely agree with the interpretation of Martinez, M and Whittem, T. as stated in their letter. Moreover, we acknowledge and appreciate their keen and detailed interest in our paper. References: González, C., Moreno, L., Fumuso, E., García, J., Rivulgo, M., Confalonieri, A., Sparo M., & Sánchez Bruni, S. (2010). Enrofloxacin-based therapeutic strategy for the prevention of endometritis in susceptible mares. Journal of Veterinary Pharmacology and Therapeutics, 33, 287-294. MacGowan, A., Rogers C., Holt, H., Wootom, M., Bowker, K., (2000). Assessment of different  antibacterial effect measures used in in vitro models of infection and subsequent use in pharmacodynamic correlations for moxifloxacin. Journal of Antimicrobial Chemotherapy, 46, 73-78 MacGowan, A., Rogers C., Holt, H., Wootom, M., Bowker, K., (2001). Pharmacodynamics of gemifloxacin against Streptococcus pneumonia in an in vitro pharmacokinetics model of infection. Antimicrobial Agents and Chemotherapy 45, 2916-2921 Martínez, M., McDermott, P.& Walker, R. (2006) Pharmacology of the fluoroquinolones: a perspective for the use in domestic animals. The Veterinary Journal, 172, 10–28. Prof. Sergio F. Sánchez Bruni Laboratory of Pharmacology Faculty of Veterinary Medicine Universidad Nacinal del Centro de la Pcia. De Buenos Aires Tandil- Argentina Email:ssanchez@vet.unicen.edu.ar