Trichomonas gallinae is a flagellated protozoon which parasitizes in the upper digestive tract of different birds,
especially columbiformes (doves and pigeons) and falconiformes. The parasite is also a common inhabitant of
the crop of psittacine birds and is frequently detected in budgerigars. The lesions associated with T. gallinae
infection of the upper digestive tract range from mild inflammation of the mucosa to large caseous lesions that
block the lumen of the oesophagus. Nitroimidazoles are considered to be the drugs of choice for the treatment
of trichomonosis. However, only a few studies report the existence of resistant strains of T. gallinae to these
drugs. Thus, in the present investigation cloned cultures of T. gallinae obtained from budgerigars and pigeons
were analysed for the first time for their in vitro susceptibilities against four 5´-nitroimidazole derivates,
including metronidazole, dimetridazole, ronidazole and ornidazole. Significantly different minimal lethal
concentrations (MLCs) were observed for them against all four drugs. The lowest MLCs revealed the
Trichomonas isolates obtained from two budgerigars, ranging from 2.0±0.3 to 3.0±0.7 μg/ml for
metronidazole and dimetridazole, and from 2.0±0.6 to 6.7±1.7 μg/ml for ornidazole and ronidazole.
Contrary to this, the highest MLCs were recorded for one Trichomonas isolate obtained from a pigeon, ranging from 83.3±6.7 (for dimetridazole and ronidazole) to 103.3±3.3 μg/ml (for metronidazole and ornidazole). The data obtained for the resistance testing were further compared with already available genetic data of the small subunit rRNA gene sequences and ITS-1, 5.8S rRNA and ITS-2 sequences, indicating a certain correlation between in vitro results and strain relationships. |
