Comparison of three anaerobic culture techniques amd media for viable recovery of subgingival plaque bacteria.

Various methods are available for viable recovery of bacteria from subgingival plaque, but their relative efficiency is not clear. In the first experiment, with 10 patients, three anaerobic techniques (Brewer jars, chamber and role tubes) and three agar media (trypticase soy with 5% sheep blood (TS), brucella agar with 5% blood and 0.5 microgram/ml of menadione (B), and modified medium 10 with 3% blood (MM 10) were compared. In the second experiment, with another 10 patients, Brewer jars were compared with a glove box, using TS. Subgingival plaque was sampled with a gas flushed broach passed through a syringe. Significance of differences in viable recoveries was determined by ANOVA. Brewer jars and chamber (aerobic plating) were comparable in efficiency, but excelled roll tubes (anaerobic inoculation). TS was better than B, but equivalent to MM 10. TS in Brewer jars (aerobic plating) matched TS in the glove box (anaerobic plating), but performed better than all the other procedures tested. Recoveries did not differ on pre- and non-prereduced plates and on commercial and laboratory, freshly made plates. Non-evacuated jars sealed inside the box (anaerobic plating) provided lower recoveries than jars evacuated, filled and sealed outside (aerobic plating). Roll tubes benefited most by extending incubation from 7 to 14d. Commercial, non-prereduced TS agar plates incubated in Brewer jars of a glove; box are highly recommendable methods for processing of subgingival plaque.