The detection of Mycoplasma sturni and Mycoplasma moatsii from the choana of a barn swallow (Hirundo rustica): a case report

Mycoplasmas are found in many different species. Until now 26 avian mycoplasma species have been described, but in the most free ranging bird species the prevalence and significance of Mycoplasma spp. is still unclear. In May 2021 a barn swallow (Hirundo rustica) was brought to a veterinary clinic after it hit a window. As part of the routine exam a choanal swab was taken for mycoplasma culture and for the detection of mycoplasmas using a Mycoplasma-genus-specific Polymerase chain reaction. Six single colony subcultures were obtained by the cultivation. Obtained subcultures were investigated by sequencing the 16S rRNA and the 16S-23S rRNA intergenic transcribed spacer region sequence. The 16S rRNA gene sequence from one subculture had a homology of 99.03% and the 16S-23S rRNA intergenic transcribed spacer region sequence of 100% with the sequence of Mycoplasma sturni. The 16S rRNA gene sequence from the other five subcultures shared a homology of 99.89% and the 16S-23S rRNA intergenic transcribed spacer region sequence of 99.81% with the sequence of Mycoplasma moatsii. According to the available literature this is the first report about the detection of M. moatsii, in the respiratory tract of a barn swallow. M. moatsii was previously only found in grivit monkeys (Cercopithecus aethiops), Norway rats (Rattus norvegicus) and a mute swan (Cygnus olor). The role of mycoplasmas in barn swallows is still unknown, especially as in the present case both mycoplasma species do not seem to cause clinical symptoms.