Antimicrobial minimum inhibitory concentration of Mycoplasma gallisepticum: a systematic review

Pharmacokinetic and Pharmacodynamic integration of tilmicosin against Mycoplasma gallisepticum in the target infection site in chickens

Mycoplasma gallisepticum (M. gallisepticum) is a primary respiratory pathogen of poultry and causes significant economic losses to the poultry industry. There were no reported articles concerning the Pharmacokinetics/Pharmacodynamics (PK/PD) interactions of tilmicosin against M. gallisepticum in vivo. In the current study, we established an in vivo M. gallisepticum infection model and tilmicosin was administered orally to the M. gallisepticum-infected chickens by different dosage regimens. The concentration of tilmicosin in lung tissue was determined by high-pressure liquid chromatography/tandem mass spectrometry (HPLC–MS/MS), besides the counting of the viable colony of M. gallisepticum in lung tissue was also monitored dynamically to appraise the PK/PD interactions of tilmicosin against M. gallisepticum. We found that anti-mycoplasmal activity was concentration-dependent and mycoplasmacidal activity was observed at tilmicosin dosage >7.5 mg/kg. The PK/PD parameter of AUC/MIC (The area under the concentration–time curve divided by the minimal inhibitory concentration) correlated well with anti-mycoplasmal efficacy (R² = 0.92). The ratios of AUC/MIC for 1 log₁₀ and 3 log₁₀ colony-forming units [CFU]/lung reductions were 300.02 and 6,950.15 h, respectively. These findings indicated that tilmicosin may be therapeutically effective in chickens to treat M. gallisepticum lung infections if administered at a dose of 9.12 mg/kg.

The Ring-Necked Pheasant (Phasianus colchicus) Industry within the United Kingdom and the Threat Posed by Mycoplasma gallisepticum: A Review

Simple Summary

In ring-necked pheasants (Phasianus colchicus), Mycoplasma gallisepticum (MG) infection is frequently associated with infectious sinusitis. This condition causes swelling of the infraorbital sinuses, upper respiratory distress, depression and variable levels of mortality, and is considered one of the most important clinical and economic diseases of pheasants. This review provides a brief overview of the structure of the UK pheasant industry, with reference to the various stages within the supply chain, common diseases and challenges facing the industry. The current understanding of MG transmission, prevalence, clinical expression, diagnosis and control strategies in pheasants is subsequently summarised. In addition, this review aims to assess the current gaps in knowledge relating specifically to MG in pheasants, with reference and extrapolation where appropriate to data gathered from other species. This review will be of particular interest to clinicians in the field when planning MG control or treatment strategies in pheasants. It may also be of academic interest as it provides a summary of poorly studied areas.

Abstract

In ring-necked pheasants (Phasianus colchicus), Mycoplasma gallisepticum (MG) infection is frequently associated with infectious sinusitis. This condition causes swelling of the infraorbital sinuses, upper respiratory distress, depression and variable levels of mortality, and is considered one of the most important clinical and economic diseases of pheasants. This review provides a brief overview of the structure of the UK pheasant industry, with reference to the various stages within the supply chain, common diseases and challenges facing the industry. The current understanding of MG transmission, prevalence, clinical expression, diagnosis and control strategies in pheasants is subsequently summarised. In addition, this review aims to assess the current gaps in knowledge relating specifically to MG in pheasants, with reference and extrapolation where appropriate to data gathered from other species.

The Monitoring of Mycoplasma gallisepticum Minimum Inhibitory Concentrations during the Last Decade (2010–2020) Seems to Reveal a Comeback of Susceptibility to Macrolides, Tiamulin, and Lincomycin

Mycoplasma gallisepticum (Mg) is a highly contagious avian pathogen responsible for significant economic losses for the poultry industry. In some circumstances, antimicrobial treatment is useful to contain clinical signs of Mg infection in birds. However, antimicrobial resistance emergence is now common among animal pathogens, becoming a worldwide health concern. The collection of minimum inhibitory concentration (MIC) data is fundamental for an appropriate antimicrobial use and for fighting antimicrobial resistance emergence. However, MIC data can only be generated in specialized laboratories, and therefore they are not regularly available. MICs of 67 non-vaccine-derived Mg isolates collected in Italy between 2010 and 2020 were obtained. Although 79.1% of the Mg isolates showed enrofloxacin MICs ≥ 8 µg/mL, a statistically significant trend toward low MICs of erythromycin, tylosin, tilmicosin, spiramycin, tiamulin, and lincomycin was observed, indicating a comeback to susceptibility of Mg toward these drugs. Doxycycline proved to be slightly more effective than oxytetracycline. The present study shows that Mg changed its susceptibility toward many of the drugs most commonly used for its containment over a ten-year period.