The growth of micro-organisms in intravenous fluids

Microbial contamination of single- and multiple-dose vials after opening in a pulmonary teaching hospital

Objectives

Methods

Results

Conclusions

Warming of infusion syringes caused by electronic syringe pumps

PURPOSE

To evaluate inadvertent warming of the infusion syringe in four different types of electronic syringe pumps.

METHODS

Ambient temperature and syringe surface temperature were simultaneously measured by two electronic temperature probes in four different models of commercially available syringe pumps. Experiments were performed at an infusion rate of 1 ml h(-1) using both battery-operated and main power-operated pumps. Measurements were repeated four times with two pumps from each of the four syringe pump types at a room temperature of approximately 23 degrees C. Differences among the four syringe pump brands regarding ambient to syringe temperature gradient were compared using ANOVA. A P-value of less than 0.05 was considered statistically significant.

RESULTS

Syringe warming differed significantly between the four syringe brands for both the battery-operated and main power-operated mode (ANOVA, P< 0.001 for both modes). Individual differences between syringe surface and ambient temperature ranged from 0.3 to 1.9 degrees C for battery operation and from 0.5 to 11.2 degrees C during main-power operation.

CONCLUSION

Infusion solutions can be significantly warmed by syringe pumps. This has potential impact on bacterial growth and the stability of drug solutions and blood products infused, as well as on the susceptibility to hydrostatic pressure changes within the infusion syringe.

Propofol emulsion and bacterial contamination

Package insert information provided with propofol advises prompt administration following its drawing-up. This study has examined the delays which occur between drawing-up and administration of propofol in clinical practice and the incidence of bacterial contamination occurring under such conditions. Two hundred and fifty-four clinical uses of propofol were examined. Mean elapsed times (range) from drawing-up to induction were 28.8 min (1-172), and 11.6 min (1-65) from induction to culture inoculation. The delay to induction exceeded ten minutes in 68.5% of propofol uses. Sixteen cultures (6.3%) grew bacteria. Delay to induction was not associated with increased chances of bacterial growth in any of the samples. Increasing delay between induction and culture inoculation was associated with greater odds of bacterial growth, which is consistent with contamination occurring at or after induction. Whilst the manufacturers advise prompt administration, our findings show that when inadvertent delays occur, propofol remains bacteriologically safe to use under standard clinical conditions. Microbial contamination can occur at any stage, thus attention to asepsis remains important throughout the administration period.

Comparative study between liquid and solid media for the detection of bacterial contamination in intravenous solutions

For the sterility testing of intravenous solutions, the Pharmacopeia recommend the use of liquid media. However, contamination by a single micro-organism during the test may lead to the inappropriate blocking of the release of the batch. An alternative method using solid media for culturing the membranes used in the filtration was therefore sought. With an artificial contamination with 10-100 colony-forming-units (cfu) of nine different micro-organisms, including those advocated by the Pharmacopeia, the feasibility of two different methods was assessed using two different intravenous solutions manufactured in our hospital. The results show that recoveries of minute amounts of bacteria using solid media and liquid media were similar. In all experiments there was a concordance in both positive and negative results. However, the batches of solutions have to be tested as quickly as possible after their preparation, whatever the method used, to avoid false-negative tests.