Effect of chilling on the survival of Bacteroides fragilis

Publisher Website
Google Scholar
Abstract
Factors affecting the susceptibility of B. fragilis ssp. fragilis to low temperature were examined [with regard to diagnostic implications]. Predetermined numbers of cells were spread on agar media or suspended in enriched Trypticase soy broth and exposed to low temperature under both aerobic and anaerobic conditions. Exposure of 18 h growth of a freshly isolated B. fragilis strain to 4.degree. C aerobically or anaerobically resulted in a loss of at least 50% viability after 12 h. B. fragilis cells in early growth (6 h) were more tolerant to exposure at 4.degree. C than older cells (18 h). When the freshly isolated strain was repeatedly subcultured in the laboratory it was uniformly more cold tolerant than fresh clinical isolates. The incorporation of 1.0 M sucrose and 5 mM MgCl2 into liquid media partially alleviated the lethal effects of cold temperature on B. fragilis ssp. fragilis.