Influences of swab types and storage temperatures on isolation and molecular detection of Mycoplasma gallisepticum and Mycoplasma synoviae

Routine diagnosis of Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) is performed by collecting oropharyngeal swabs, followed by isolation and/or detection by molecular methods. The storage temperature, storage duration and the type of swab could be critical factors for successful isolation or molecular detection. The aim of this study was to compare the influence of different types of cotton-tipped swab stored at different temperatures, on the detection of MG and MS. To achieve this, combined use of traditional culture analysis (both agar and broth), with modern molecular detection methods was utilized. Performances of wooden and plastic shaft swabs, both without transport medium, were compared. Successful culture of M. gallisepticum was significantly more efficient from plastic swabs when compared to wooden, whereas no difference was seen for the re-isolation of M. synoviae. Storage at 4°C compared to room temperature also increased the efficiency of culture detection for both Mycoplasma species. When stored at room temperature, PCR detection limits of both MG and MS were significantly lower for wooden compared to plastic swabs. The qPCR data showed similar detection limits for both swab types when stored at both temperatures. The results suggest that swabs with a plastic shaft are preferred for MG and MS detection by both culture and PCR. While a lower storage temperature (4°C) is optimal for culture recovery, it seems that both temperatures investigated here are adequate for molecular detection and it is the swab type which carries a greater influence.