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| Question | Answer |
| What is the microscopic appearance of Rhodococcus? | Gram +, pleomorphic, non-motile |
| How to detect Rhodococcus? | PCR and cytology. If false negative, thoracic radiographs are helpful for diagnosis. |
| What tests do we do for identification of Rhodococcus? One is specific for R..equi: | Cat + Ox - Gram + CAMP test |
| What is the principle of CAMP test? | R.equi produces phospholipases that enhance the hemolytic activity of S.aureus B toxin. |
| What do you know on Rhodococcus resistance and sensitivity? | RESISTANT- to acid (phaagolysosomes), UV light, desiccation= persists in eq. environment. To β lactams and TE SENSITIVE- to most Abs for G+ |
| Is rhodococcus resistant to penicillin? | Yes |
| What is one property that protects R.Equi from the immune system of the host? (similar to M.tuberculosis) | 1) prevents fusion of phagosome and lysosome 2) Inhibits respiratory burst. These allow R.equi to multiply within the phagosome shielded by the immune system. Survives in macrophages |
| Which strain of Rhodococcus affects plants? | R.fascians- phytopathogen- leafy gall disease. |
| What species are hosts to R.equi? | Pigs- In lymph nodes Goats and Cattle- RARE Humans- if immunosup. pulmonary inf. HORSES- bronchopneumonia in foals |
| What is the result of R.equi infection in horses? | Infection of macrophages in lungs where it replicates and damage the surrounding tissue. Leaves host w/ immunosuppression towards other respiratory infections. |
| How is R.equi transmitted? | By ingestion or inhalation. Mostly in summer when manure is dry-- aerosolization= inhale |
| What important factor does Rhodococcus have that is the cause of infections? | 85-90kb Virulence plasmid. Bacteria lacking this plasmid are non-infectious. |
| What other virulence factors does it have? | LAM- lipos-arbaino-mannan: cell envelope lipid. Also cell wall lipids that affect recognition by the immune system of host within CD1-T cell. |
| what is the result of rhodococcus infection in goats? | Hepatic abscesses but rare |
| What samples are used for testing? | Trans-Tracheal washes |
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