For example, S. aureus and S. pyogenes are known to overgrow other bacteria on swabs when processing delay increases, and both S. pneumoniae and NTHi are fastidious organisms more likely to perish after 6 hours and in conditions of freezing.
Ten coupons were used for each swab material, swab preparation, and processing protocol to be evaluated.
Because at least this obstacle is overcome by our sampling technique and can be ruled out as a confounding factor, we investigated the effect of loading nylon-flocked swabs with predefined concentrations of immune mediators using two different consecutive protocols of processing the swabs.
These results suggest that adequate DNA for PCR-based applications can be obtained from buccal swabs, but sampling or processing considerations may be important in obtaining optimal results.
We thank the Tierseuchenkasse MV for collecting samples, Katja Levin for processing the poultry swabs and the Landesamt für Landwirtschaft, Lebensmittelsicherheit und Fischerei MV for processing samples and the support in planning the study.
Dry swabs were frozen at -80°C until processing for PCR.
Once in the laboratory, swabs were stored at 4°C until processing.
The advantage of removing the swab prior to transport is that it eases processing for the diagnostic lab, eliminates the loss of media due to absorption by the swabs, and reduces the potential for cross-contamination by aerosols in the event that the swabs are removed in the lab.
Processing involved inserting 2 cotton-tipped swabs into the specimen (if dysentery was present, an area of blood or mucus was swabbed); one swab was placed into modified Cary-Blair transport medium [ 29], and the other into buffered glycerol saline [ 30].
