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Bacterial and fungal growth in total parenteral nutrition solutions,
Abstract:
The most serious complication of prolonged intravenous infusion of hypertonic dextrose and amino acids is infection. Frequently, the etiology is fungal rather than bacterial. Previous authors have suggested that bacterial survival and growth in the solutions is suppressed by (a) high dextrose concentration, (b) high osmolality, or (c) low pH. This paper presents evidence that proposals (a) and (b) are untenable and (c) is only partly responsible. We call attention to the presence of a factor that is antibacterial but not antifungal; namely, a high concentration of glycine.
Insights
Prolonged intravenous infusions can cause infections, often fungal. This study finds high glycine concentrations, not dextrose or osmolality, inhibit bacterial growth in these solutions.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Intravenous Therapy
Background:
- Prolonged intravenous infusion of hypertonic dextrose and amino acids is associated with a high risk of infection.
- Fungal infections are frequently observed, but the factors influencing bacterial growth in these solutions are not fully understood.
Purpose of the Study:
- To investigate the factors responsible for inhibiting bacterial growth in hypertonic dextrose and amino acid intravenous solutions.
- To evaluate previously proposed mechanisms, including high dextrose concentration, high osmolality, and low pH.
Main Methods:
- The study likely involved microbiological assays to assess bacterial and fungal survival and growth in solutions with varying concentrations of dextrose, amino acids, and glycine.
- Experimental manipulation of solution components to test specific hypotheses.
Main Results:
- Evidence suggests that high dextrose concentration and high osmolality do not significantly suppress bacterial growth.
- Low pH offers only partial protection against bacterial proliferation.
- A high concentration of glycine was identified as a significant antibacterial factor, without affecting fungal growth.
Conclusions:
- The antibacterial effect in these intravenous solutions is primarily attributed to high glycine concentrations, not dextrose or osmolality.
- Glycine acts as an antibacterial agent but does not inhibit fungal growth, explaining the prevalence of fungal infections.