Rhodococcus Enfeksiyonları
Özet
Rhodococcus, Nocardiaceae ailesi içinde sınıflandırılan fakültatif hücre içi bakteridir. Rhodococcus cinsinde birçok bakteri türü bulunmaktadır. Veteriner hekimlik açısından Rhodococcus equi patojen olarak kabul edilen tek bakteri türüdür. R. equi, gram pozitif, pleomorfik kokobasildir. Gram pozitif, aerobik bir toprak saprofitidir. 6 aylıktan küçük taylarda fırsatçı bir patojendir. R. equi, kanlı agarda ürer. Kapsül ve pigment üretir. Karakteristik mukoid somon - pembe koloniler üretir. Katı kültür ortamında yaklaşık 1–5 μm boyutlarında kokoid olarak görünür. R. equi, atların bulunduğu her yerde toprakta bulunur. Kalabalık at çiftliklerinde endemik hale gelebilir. Enfekte taylar, çevre kirliliğinin başlıca kaynağıdır ve her gram dışkıda 106 -108 bakteri saçabilirler. Yetişkin atlar da dışkılarında bakteri saçabilirken, bu genellikle sporadik olarak ve çok daha az miktarda bakteri ile meydana gelir. Çevreden bakteri bulaşması genellikle sindirim veya solunum yoluyla gerçekleşir. R. equi toprakta yaşayabilir. R. equi, fagositozdan sonra makrofajlar içinde yaşayabilen fakültatif bir hücre içi patojendir. Transtrakeal yıkamalar en iyi tanı yöntemi olarak kabul edilir. R. equi’nin antemortem tanısında genel olarak gold standart olarak kabul edilen yöntem, trakeobronşiyal aspirattan (TBA) bakteri varlığını doğrulamaktır. Endemik çiftliklerdeki subklinik olarak enfekte olmuş tayların yaklaşık %44’ü antimikrobiyal tedavi olmaksızın iyileşir. Klinik hastalığı olan taylar, bir makrolid antibiyotik ve rifampin kombinasyonu ile tedavi edilir.
Rhodococcus is a facultative intracellular bacterium classified in the family Nocardiaceae. There are numerous species of bacteria in the genus Rhodococcus, but in terms of veterinary medicine, only R. equi is recognised as a pathogenic species.R. equi is a gram positive, pleomorphic coccobacillus and a gram positive, aerobic soil saprophyte. It is an opportunistic pathogen in foals under 6 months of age. It is a gram positive, aerobic, saprophytic bacterium that grows on blood agar, producing a capsule and pigment, and characteristic mucoid salmon-pink colonies. On solid culture media, it appears as coccoid, approximately 1-5 μm in size.R. equi is found in soil wherever horses are present, and can become endemic in crowded horse farms. Infected foals are the main source of environmental pollution, shedding 106-108 bacteria per gram of faeces. While adult horses can also shed bacteria in their faeces, this usually occurs sporadically and with much smaller amounts of bacteria. Transmission of bacteria from the environment usually occurs through ingestion or inhalation.R. equi can live in soil and is a facultative intracellular pathogen that can survive within macrophages after phagocytosis. Transtracheal washes are considered the best diagnostic method. The generally accepted gold standard method for the antemortem diagnosis of R. equi is to confirm the presence of bacteria from tracheobronchial aspirate (TBA).Approximately 44% of subclinically infected foals on endemic farms recover without antimicrobial treatment. Foals with clinical disease are treated with a combination of a macrolide antibiotic and rifampin.
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