Multidrug therapy of Mycobacterium avium subsp. avium infection in experimentally inoculated budgerigars (Melopsittacus undulatus).

The aim of the study was to determine whether the four-month experimental therapy of mycobacteriosis in budgerigars may cause a complete recovery. A group of nine budgerigars was infected with a Mycobacterium avium subsp. avium isolate with proven pathogenicity for budgerigars. Five weeks post-inoculation, multidrug therapy was started. Another group comprising six birds received the same treatment but no infection, and the third group also comprising six birds was kept without infection or treatment as a control. The adopted antibiotic regimen included clarithromycin 61 mg/kg b.w., moxifloxacin 25 mg/kg b.w. and ethambutol 60 mg/kg b.w. administered by crop gavage every 12 h for 18 weeks. Despite a significant improvement in the condition of the infected, treated birds, the four-month therapy was not sufficient for the complete recovery of all.

Formulation and efficacy of liposome-encapsulated antibiotics for therapy of intracellular Mycobacterium avium infection.

Mycobacterium avium is an intracellular pathogen that can invade and multiply within macrophages of the reticuloendothelial system. Current therapy is not highly effective. Particulate drug carriers that are targeted to the reticuloendothelial system may provide a means to deliver antibiotics more efficiently to M. avium-infected cells. We investigated the formulation of the antibiotics ciprofloxacin and azithromycin in liposomes and tested their antibacterial activities in vitro against M. avium residing within J774, a murine macrophage-like cell line. A conventional passive-entrapment method yielded an encapsulation efficiency of 9% for ciprofloxacin and because of aggregation mediated by the cationic drug, was useful only with liposomes containing < or = 50 mol% negatively charged phospholipid. In contrast, ciprofloxacin was encapsulated with > 90% efficiency, regardless of the content of negatively charged lipids, by a remote-loading technique that utilized both pH and potential gradients to drive drug into preformed liposomes. Both the cellular accumulation and the antimycobacterial activity of ciprofloxacin increased in proportion to the liposome negative charge; the maximal enhancement of potency was 43-fold in liposomes of distearoylphosphatidylglycerol-cholesterol (DSPG-Chol) (10:5). Azithromycin liposomes were prepared as a freeze-dried preparation to avoid chemical instability during storage, and drug could be incorporated at 33 mol% (with respect to phospholipid). Azithromycin also showed enhanced antimycobacterial effect in liposomes, and the potency increased in parallel to the moles percent of negatively charged lipids; azithromycin in DSPG-Chol (10:5) liposomes inhibited intracellular M. avium growth 41-fold more effectively than did free azithromycin. Thus, ciprofloxacin or azithromycin encapsulated in stable liposomes having substantial negative surface charge is superior to nonencapsulated drug in inhibition of M.avium growth within cultured macrophages and may provide more effective therapy of M.avium infections.