Efficacy of Danofloxacin and Tylosin in the Control of Mycoplasmosis in Chicks Infected with Tylosin-Susceptible or Tylosin-Resistant Field Isolates of Mycoplasma gallisepticum

Abstract

The efficacy of danofloxacin was compared with that of tylosin in the control of induced mycoplasmosis. In three experiments, disease was induced in broiler chicks by intrapulmonary injection of field isolates of Mycoplasma gallisepticum (MG) originating from Brazil, a different isolate being used for each experiment. Starting the day after inoculation, groups of chicks were medicated for 3 days via the drinking water with danofloxacin (50 ppm) or tylosin (500 ppm) or were left as unmedicated controls. Chicks were observed for 21 days. A severe mycoplasmosis was induced in unmedicated birds, characterized by mortality, depression, and respiratory signs. Danofloxacin was highly efficacious in controlling this infection in all three experiments, whereas tylosin was efficacious in only one. This difference could be related directly to the reduced in vitro susceptibility to tylosin displayed by the two isolates of MG. In the two experiments where isolates were tylosin-resistant, danofloxacin was significantly (P < or = 0.05) superior to tylosin in reducing mortality, maintaining weight gain, and reducing the prevalence of air-sac lesions, isolation of MG, and seroconversion.

Study of danofloxacin depletion in eggs of laying hens after oral administration

“…The spectrum of antimicrobial activity of danofloxacin is wide and includes most Gram-negative bacteria, some Gram-positive bacteria and mycoplasmas [2,3]. Owing to its high concentration in chicken lung [4,5], danofloxacin has been widely used in China for the control of respiratory bacterial infections in chickens [6,7], bovine and swine since 1999. However, a recent investigation performed in China showed that the percentage of Escherichia coli isolates from Chinese poultry resistant to fluoroquinolones was fairly high (57.1-66.7%) [8].…”

Comparative study of the plasma pharmacokinetics and tissue concentrations of danofloxacin and enrofloxacin in broiler chickens

“…The drugs are widely distributed to various tissues in the body resulting in target tissue concentrations significantly higher than those achieved in blood ( Giles et al ., 1991 ; Intorre et al ., 1997 ). There are several reports describing their good therapeutic efficacy against various bacterial and mycoplasmal infectious diseases in poultry ( Bauditz, 1987; Jordan et al ., 1993 ; Migaki et al ., 1993 ; Kempf et al ., 1995 ; Charleston et al ., 1998 ).…”

Sequencing Analysis of <b><i>Mycoplasma gallisepticum</i></b> Wild Strains in Vaccinated Chicken Breeder Flocks

“…Another important finding was the de-cline of positive serology percent after 20 weeks of age, reaching the minimum of only 36% of flocks being positive at week 38. This decline could be attributed to massive misuse of antibiotics (MG sensitive), and as a result vaccine MG colonization was affected [Jordan, 1979;Migaki et al, 1993]. It seems that this was the appropriate time for field infection to occur.…”