Antibacterial Spectrum of Baytril®

Baytril® is a veterinary antibiotic active against most relevant bacteria in small animal practice, particularly in dogs and cats. The antibacterial spectrum includes gram-negative and gram-positive organisms.

Antibacterial spectrum

In Vitro Antibacterial Activity

The determination of minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC), and examination of time-kill kinetics are recognized in vitro methods. Together with other experimental data (plasma and tissue kinetics), they allow a rough prognosis of probable in vivo antimicrobial efficacy.

Minimum Inhibitory Concentrations (MICs)

In the table, susceptibility data of bacteria isolated from clinical dog and cat patients against Baytril® are shown (12).

Minimum Bactericidal Concentrations (MBCs)

In immunocompromised patients suffering from chronic recurrent diseases, therapy with bactericidal anti-infectives is required. Plasma and tissue concentrations achieved with recommended doses of Baytril® show a pronounced bactericidal effect against growing and stationary bacteria as well as a favorable antibacterial killing (11), (12). Baytril® has also been demonstrated to exhibit strong bactericidal activity against bacteria such as E. coli growing under anaerobic culture conditions (11). Obligate anaerobes, however, such as the commensal gut flora, are not affected by Baytril®.

Microbiolog MIC values

MIC values – MICs/MBCs of FQs

Bactericidal activity against E.coli

Bactericidal activity against E. coli

Time-kill kinetics of FQs


(11) Wetzstein HG, DeJong A: In vitro bactericidal activity and post antibiotic effect of fluoroquinolones used in veterinary medicine. Suppl Compend Contin Educ Pract Vet 18 (2): 22–29, 1996.
(12) Pirro F, Edingloh M, Schmeer N: Bactericidal and inhibitory activity of enrofloxacin and other fluoroquinolones in small animal pathogens.: Suppl Compend Contin Educ Pract Vet 21 (12): 19–25, 1999.