The Minimum Inhibitory Concentration of Tilmicosin and Tylosin for Mycoplasma gallisepticum and Mycoplasma synoviae and a Comparison of Their Efficacy in the Control of Mycoplasma gallisepticum Infection in Broiler Chicks

Abstract

The minimum inhibitory concentrations of tylosin tartrate and a new macrolid antimicrobial agent, tilmicosin, were assessed for six strains of Mycoplasma gallisepticum (MG) and three strains of Mycoplasma synoviae (MS) in vitro by the microbroth method. For four of the strains of MG, tilmicosin showed a slightly lower minimum inhibitory concentration (MIC) than did tylosin at both the initial reading (when pH 7.0 is first seen in the dilutions under test) and the final reading at 14 days of incubation. For one of the remaining strains, the MIC for tilmicosin was equal to or less than that for tylosin at the initial reading but greater at the final reading. For the other strain, the MIC for tilmicosin was greater than for tylosin, and for both of them the MICs were very much higher than for other strains. For the three strains of MS, there was little difference between the two drugs for one strain whereas the MIC for tilmicosin was slightly less for the other two groups. Groups of 30 chicks were infected with a virulent strain of MG and treated with either tylosin (0.5 g/liter) or tilmicosin (at concentrations of 0.125, 0.25 or 0.5 g/liter). One infected group was untreated and another group was uninfected and untreated. Clinical signs, mainly depression and nervous signs, were seen in two to five birds in the infected treated groups. In contrast, in the infected untreated group, 16 of 30 birds showed clinical signs. Mortality was significantly less in the infected treated groups compared with the infected untreated group (P < 0.001), and following infection there were significantly (P < 0.05) greater weight gains in the infected medicated groups. At necropsy the prevalence of gross lesions of the airsac walls was similar in all the infected medicated groups and was less than that for the infected unmedicated group. For the group on tylosin, MG was recovered from five chicks during life and from six dead chicks. The corresponding figures for the group receiving the lowest dose of tilmicosin were four for each; however, the organism was not recovered from the groups on the higher doses of tilmicosin either during life or from dead chicks. Serological results were negative for all groups except the infected untreated group, in which all three birds that were tested were positive.

Pharmacokinetics, tissue residues of tilmicosin phosphate (tilmicor-al®) and its in vitro and in vivo evaluation for the control of Mycoplas-ma gallisepticum infection in broiler chickens

“…The MIC of tilmicosin and tylosin against MG field strain was 0.054 and 0.319 μg/mL, respectively. This result confirm that of Jordan & Horrocks (1996) who recorded that tilmicosin had a lower MIC against several tested strains of MG than that of tylosin at both initial reading (at pH 7.0) and final reading at 14 days of incubation. Regarding the in vivo evaluation of the efficacy of tilmicosin and tylosin against MG, Table 4 showed the mean clinical score in MG infected untreated and infected treated groups.…”

“…Tilmicosin at 300-500 g/ton prevented the development of air-saculitis caused by MG infection (Shryock et al 1994). In addition, the air saculitis of MGinoculated and tilmicosin medicated birds were less than that for the inoculated and unmedicated ones (Jordan & Horrocks 1996, Abd El-Ghany 2009). Furthermore, tilmicosin treatment at different concentrations for 5 days significantly diminished the respiratory signs and air sac and peritonitis lesions caused by MG (Kempf et al 1997, Charleston et al 1998, Jordan et al 1999, Abd El-Ghany 2009).…”

“…Each chicken was given a single oral (directly into crop using gavage) dose of tilmicosin phosphate (tilmicoral ® ) at a level of 25 mg/kg body weight. This dose was selected according to the manufacturer's approved daily dose, which falls within the range applied by some researchers on efficacy studies of tilmicosin in the control of Mycoplasma infection in broilers (Jordan & Horrocks 1996, Kempf et al 1997). Blood samples (1-1.5 mL) were collected from left wing vein or other veins into heparinized tubes at 0 (before dosing), 15 and 30 minutes, and at 1, 2, 4,6,8,10,12,24,48, and 72 h after dosing.…”

Comparative pharmacokinetics and bioavailability of two tylosin formulations in chickens after oral administration

“…Tylosin is a macrolide antibiotic with a minimum inhibitory concentration (MIC) values ranging from 0.01 to 0.5 μg/ml for various susceptible bacterial and mycoplasmal pathogens (Jordan and Horrocks 1996, Hannan et al 1997, Jordan et al 1998, Salmon and Watts 2000. Tylosin (Tylosina ® and Tylan ® ) was detected in chicken plasma at concentrations higher than the MIC for most susceptible microorganisms and Mycoplasma for 12 h following oral administration.…”

Postantibiotic effects and postantibiotic sub-MIC effects of tilmicosin, erythromycin and tiamulin on erythromycin-resistant Streptococcus suis

“…(20). Tilmicosin is a new macrolide antibiotic synthetically derived from tylosin, which is specially used in veterinary medicine (10,15). Tiamulin was evaluated with tilmicosin because it has similar antimicrobial mechanism with macrolide and is commonly used to treat infections in swine and poultry (3,5,13,27).…”