Experimental studies of survival of anaerobic bacteria at 4 degrees C and 22 degrees C in two different transport systems.

The survival of anaerobic bacteria on swabs in two different transport systems at 4 degrees C and 22 degrees C was evaluated. The transport systems were a charcoal-impregnated cotton swab in modified Stuart transport medium (MST), and a viscose swab in modified SIFF transport medium (BTM) (Bionor). The following eight clinical strains of anaerobic bacteria were tested for quantitative recovery at 24 h, 48 h, 72 h, and 96 h; Fusobacterium necrophorum, Bacteroides melaninogenicus, Bacteroides intermedius, Peptostreptococcus anaerobius, Peptococcus magnus, Clostridium perfringens, Clostridium tetani, and Actinomyces israelii. Additionally, a mixture of Staphylococcus aureus and Escherichia coli was tested together with Bacteroides fragilis, Fusobacterium necrophorum and Clostridium perfringens. Both transport systems preserved the bacteria, but the BTM medium gave a better quantitative recovery of the bacteria than the MST in 29/64 (45%) of the experiments, whereas the opposite was the case in 15/64 (23%) of the experiments (p < 0.05). There was no significant strain-related difference between the recovery of 10 different B. fragilis strains. There was no major difference in the recovery of the anaerobes in the two systems at 4 degrees C compared to 22 degrees C, except for Fusobacterium necrophorum, which survived best at 4 degrees C in the Bionor transport system.