The in vitro effects of proxymetacaine, fluorescein, and fusidic acid on real-time PCR assays used for the diagnosis of Feline herpesvirus 1 and Chlamydophila felis infections. (Special Issue: Focused on feline diseases.)

摘要

Purpose: To investigate the possible inhibition of qPCR assays used for the diagnosis of ocular infections in cats by proxymetacaine, fluorescein, and fusidic acid, which are commonly used in veterinary ophthalmology. Methods: Fluorescein, proxymetacaine, and fusidic acid were tested for possible inhibition of a triplex qPCR assay designed to detect Chlamydophila felis, Feline herpesvirus 1 (FHV-1), and the feline 28S ribosomal DNA (28S rDNA) gene by comparing threshold cycle (C_t) values of samples with and without the three products. A second experiment was carried out to measure the effects of various dilutions of fusidic acid. Results: No statistically significant differences were detected between the C. felis, FHV-1, and 28S rDNA C_t values with and without proxymetacaine or fluorescein. However, there was a statistically significant increase in FHV-1 (P<0.01), C. felis (P<0.01), and 28S rDNA (P<0.05) C_t values when fusidic acid was used. When dilutions of fusidic acid were tested, the results revealed that only the 1:2 dilution caused a statistically significant increase (P<0.01) in the FHV-1 Ct values. Conclusion: Proxymetacaine and fluorescein did not interfere with our qPCR assays for the detection of C. felis and FHV-1. The presence of fusidic acid caused a small inhibitory effect of doubtful clinical significance. In vivo studies are required to establish the clinical relevance of this study and to confirm our findings.