Prolonged primary incubation in the isolation of anaerobic bacteria from clinical specimens.

The value of prolonged primary anaerobic incubation for the isolation of anaerobic bacteria from clinical material was assessed by comparison of two incubation systems. Continuous incubation of primary anaerobic plates for 48 h was superior to conventional methods in that more anaerobes were isolated. The results indicate that in some cases prolonged incubation may be the only method of achieving the correct bacteriological diagnosis, particularly when relatively oxygen-sensitive strains are involved or when organisms may be damaged by exposure to oxygen during transport. Use of extended primary incubation provides a clearer picture of the microbial flora of the original lesion and reveals that some anaerobic genera may be more commonly involved than is at present recognised.