Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals.

BACKGROUND: Current screening tests for Rhodococcus equi pneumonia in foals lack adequate accuracy for clinical use. Real-time, quantitative PCR (qPCR) for virulent R. equi in feces has not been systematically evaluated as a screening test. OBJECTIVE: The objective of this study was to evaluate the accuracy of qPCR for vapA in serially collected fecal samples as a screening test for R. equi pneumonia in foals. ANIMALS: One hundred and twenty-five foals born in 2011 at a ranch in Texas. METHODS: Fecal samples were collected concurrently with thoracic ultrasonography (TUS) screening examinations at ages 3, 5, and 7 weeks. Affected (pneumonic) foals (n = 25) were matched by age and date-of-birth to unaffected (n = 25) and subclinical (ie, having thoracic TUS lesions but no clinical signs of pneumonia) foals (n = 75). DNA was extracted from feces using commercial kits and concentration of virulent R. equi in feces was determined by qPCR. RESULTS: Subsequently affected foals had significantly greater concentrations of vapA in feces than foals that did not develop pneumonia (unaffected and subclinical foals) at 5 and 7 weeks of age. Accuracy of fecal qPCR, however, was poor as a screening test to differentiate foals that would develop clinical signs of pneumonia from those that would remain free of clinical signs (including foals with subclinical pulmonary lesions attributed to R. equi) using receiver operating characteristic (ROC) methods. CONCLUSIONS AND CLINICAL IMPORTANCE: In the population studied, serial qPCR on feces lacked adequate accuracy as a screening test for clinical R. equi foal pneumonia.

Enhancement of the induction of murine thymic lymphomas by cyclosporine.

The effects of cyclosporine (CsA) on the induction of thymic lymphoma in male Swiss Webster mice were investigated using the classic model of two-stage carcinogenesis with N-methyl N-nitrosourea (MNU) as an initiator and CsA as a promoter. The mice treated with a single dose of MNU followed by chronic feeding of 0.015% CsA developed an eight-fold higher incidence of thymic lymphomas than the mice treated with a single dose of MNU followed by a basal diet. No mice treated with CsA alone or mice kept on a basal diet developed tumors. The results suggest that CsA enhances the induction of thymic lymphomas by its promoting effect and that the disturbance of thymic microenvironment induced by CsA may be one of the underlying mechanisms of the promoting action by CsA.