The PK–PD Relationship and Resistance Development of Danofloxacin against Mycoplasma gallisepticum in An In Vivo Infection Model

Abstract

Mycoplasma gallisepticum is the causative agent of chronic respiratory disease (CRD), a prevalent disease of poultry, which is responsible for significant economic losses in farms. Although several antimicrobial agents are currently recommended for the treatment and prevention of M. gallisepticum infections, investigations of M. gallisepticum have been hampered by their fastidious growth requirements and slow growth rate. As such, little work has been conducted concerning the PK/PD relationship and mechanisms of antibiotic resistance between antimicrobials against M. gallisepticum. In the present study, danofloxacin was orally administrated to the infected chickens once daily for 3 days by an established in vivo M. gallisepticum infection model. Not only the concentrations of danofloxacin in plasma and lung tissues were analyzed, but also the counting of viable cells and changes in antimicrobial susceptibility in air sac and lung were determined. The PK and PD data were fitted by WinNonlin to evaluate the PK/PD interactions of danofloxacin against M. gallisepticum. PCR amplification of quinolone resistance-determining regions (QRDRs) and DNA sequencing were performed to identify point mutations in gyrA, gyrB, parC, and parE of the selected resistant mutant strains. In addition, susceptibility of enrofloxacin, ofloxacin, levofloxacin, gatifloxacin, and norfloxacin against these mutant strains were also determined. The PK profiles indicated that danofloxacin concentration in the lung tissues was higher than plasma. Mycoplasmacidal activity was achieved when infected chickens were exposed to danofloxacin at the dose group above 2.5 mg/kg. The ratios of AUC24/MIC (the area under the concentration-time curve over 24 h divided by the MIC) for 2 log10 (CFU) and 3 log10 (CFU) reduction were 31.97 and 97.98 L h/kg, respectively. Substitutions of Ser-83→Arg or Glu-87→Gly in gyrA; Glu-84→Lys in parC were observed in the resistant mutant strains that were selected from the dose group of 1 and 2.5 mg/kg. MICs of danofloxacin, enrofloxacin, ofloxacin, levofloxacin, gatifloxacin, and norfloxacin against the resistant mutant strains with a single mutation in position-83 were higher than that with a single mutation in position-87. These findings suggested that danofloxacin may be therapeutically effective to treat M. gallisepticum infection in chickens if administered at a dosage of 5.5 mg/kg once daily for 3 days.

In Vivo Pharmacokinetic/Pharmacodynamic Profiles of Danofloxacin in Rabbits Infected With Salmonella typhimurium After Oral Administration

“…The dose proportionality of danofloxacin pharmacokinetics in the range of 1 mg/kg to 30 mg/kg was described in the S. typhimurium -infected rabbits. The dose and AUC 24 h or C max showed significant correlations, which was in accordance with a previous report ( Zhang et al, 2017 ).…”

“…The ex vivo PK/PD model of danofloxacin has been studied for several pathogens such as Escherichia coli , Mannheimia haemolytica , and Staphylococcus aureus in calves, sheep, goats, camels, chickens, and turkeys ( Aliabadi et al, 2003a , b ; Shojaee Aliabadi and Lees, 2003 ; Haritova et al, 2006 ; Serrano-Rodriguez et al, 2017 ). In vivo PK/PD modeling was also conducted in chickens against Mycoplasma gallisepticum ( Zhang et al, 2017 ). However, neither ex vivo nor in vivo PK/PD modeling of danofloxacin against S. typhimurium has been established.…”

Population pharmacokinetics for danofloxacin in the intestinal contents of healthy and infected chickens

“…The present study developed the PopPK of danofloxacin in duodenum, jejunum, and ileum of healthy and infected chickens, and identified and quantified the covariate effects on the PK profiles of danofloxacin for the first time, and the two‐compartment model best described danofloxacin concentrations in the duodenum, jejunum, and ileum. Previous PK studies of danofloxacin often were conducted in serum/plasma and lung of chickens using noncompartmental models (Zeng et al, ; Zhang et al, ). Noncompartmental method is simple and does not require assumptions to compartment model, but it is usually applicable to linear PK.…”

Pharmacokinetic/Pharmacodynamic Integration to Evaluate the Changes in Susceptibility of Actinobacillus pleuropneumoniae After Repeated Administration of Danofloxacin

“…Danofloxacin concentrations in TCF were determined by high-performance liquid chromatography with fluorescence detection (HPLC-FD; Agilent Technologies, United States; Zhang et al, 2017 ). Briefly, after thawing, each sample (200 μL) including the blank sample was added to the same volume of acetonitrile for deproteinization, and was then clarified by centrifugation at 12,000 × g for 10 min.…”