Mycoplasma species commonly colonize the respiratory tract of normal dogs and cats and have also been shown to be a respiratory pathogen. Culture is the gold standard for identifying Mycoplasma sp; however, the organism is notoriously difficult to grow. PCR is faster and does not rely on organism viability for identification. The purpose of this study was to compare results of PCR and culture for the detection of Mycoplasma species in respiratory tract samples.
Records of the University of Georgia Veterinary Teaching Hospital and the Athens State Veterinary Diagnostic Lab were searched for dogs and cats with respiratory disease that had a Mycoplasma PCR and Mycoplasma culture (MC) performed on the same day from the same respiratory specimen. Data collected included site and method of sample collection and results of PCR, MC, other cultures, and cytology.
Results showed moderate agreement between PCR and culture for the detection of Mycoplasma (24 of 30 samples; kappa coefficient 0.59). Sensitivity and specificity of PCR were 81.8% and 78.9%, respectively, using MC as the gold standard. There were no significant differences between proportion of false positives (13%) or false negatives (7%) (p=0.4142). The six discordant results were further characterized as four PCR+/MC- and two PCR-/MC+ samples. Sixty-seven percent (4/6) of the discordant results were obtained on mailed samples.
PCR compared favorably to culture for the identification of Mycoplasma spp. in respiratory tract samples obtained from dogs and cats with respiratory disease. Discordant results occurred more commonly in mailed samples.