Survival of beta-lactamase-producing and -nonproducing bacteria in intravenous solutions

The survival of beta-lactamase-producing (beta-lac+) and non-beta-lactamase-producing (beta-lac-) Bacillus and Staphylococcus spp. has been investigated in dextrose 5% injection, NaCl 0.9%, and dextrose 5% in NaCl 0.9% solutions. Tests were performed under static and turbulent conditions of incubation, with and without antibiotics added to the fluids, and with or without 1% citrated blood. All solutions were inoculated with about 1000 organisms/mL, and sampled for viable bacteria at specific time intervals. Under static conditions, there was no significant decrease in viability (p greater than 0.01) of the bacilli, except for the staphylococci (p less than 0.01). However, when cultures were agitated, all species showed significant decline in viability (p less than 0.01). When antibiotics were present, S. aureus (beta-lac+) declined gradually throughout 24 hours (p greater than 0.01). B. cereus (beta-lac+) concentrations were static in all solutions. All organisms multiplied rapidly in solutions containing blood. The results suggest that the growth characteristics of both beta-lac+ and beta-lac- bacteria in intravenous fluids are essentially similar, except in solutions containing beta-lactamase-sensitive antibiotics in which beta-lac+ bacteria tend to survive.