Anaerobes survive in clinical specimens despite delayed processing

Quantitative cultures were performed on 11 purulent specimens of at least 2 ml from mixed aerobic anaerobic infections to determine the effect of prolonged exposure to air on the recovery of anaerobes. The specimens were processed immediately and after air exposure for periods of 10 min and 1, 4, and 24 h. There were a total of 37 anaerobic strains recovered from these specimens. Of the anaerobes, 26 were isolated with the initial processing and 22 were still present after air exposure for 24 h. The numerical concentrations of anaerobes showed little change with the sequential samplings. Eleven anaerobic strains were not detected in the initial culture but appeared sporadically in subsequent cultures. Using the types of specimens and method of processing employed in this study, most pathogenic anaerobes survived in purulent exudate despite extended periods of air exposure. The major cause of discrepent results with periodic cultures was attributed to vagaries in sampling.