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Growth of microorganisms in total parenteral nutrition mixtures and related clinical observations
Abstract:
The effect of lipid addition to TPN (Total Parenteral Nutrition) solutions on microbial growth was investigated. Staphylococcus epidermidis, which failed to grow or grew poorly in the absence of lipid, reached greater than 10(4) cfu/ml (colony forming units per ml), from an initial inoculum of approximately 50 cfu/ml after 24 h when lipid was added. Candida albicans grew more slowly in the presence of lipid, but nevertheless reached 10(4) cfu/ml after 40 h incubation. Klebsiella aerogenes grew readily in all solutions, whereas Escherichia coli failed to grow in any solution. Growth of S. epidermidis and K. aerogenes was improved when the inoculum consisted of starved cells; however, growth of starved cells of C. albicans lagged behind that of unstarved cells. The ability of S. epidermidis to grow in lipid-containing TPN mixtures is particularly important, since this organism is frequently associated with sepsis. In an infant surgical unit, where TPN is under the care of a nutrition team, samples of TPN fluids and giving sets were examined for microbiological contamination at the end of the 24 h administration period. Contamination was found in eight of the 98 systems examined from eight patients. The organisms were identified as coagulase-negative staphylococci and diphtheroids.
Insights
Lipid addition to Total Parenteral Nutrition (TPN) solutions enhances the growth of Staphylococcus epidermidis, a common cause of sepsis. Microbial contamination in TPN systems is a significant concern, particularly in infant surgical units.
Area of Science:
- Microbiology
- Clinical Nutrition
- Infectious Diseases
Background:
- Total Parenteral Nutrition (TPN) is a critical method for delivering nutrients intravenously.
- Microbial contamination of TPN solutions poses a significant risk of infection, especially in vulnerable patient populations.
- The role of lipid emulsions in TPN on microbial proliferation requires thorough investigation.
Purpose of the Study:
- To investigate the impact of lipid addition to TPN solutions on the growth of specific microorganisms.
- To assess the clinical relevance of microbial contamination in TPN administration systems within an infant surgical unit.
Main Methods:
- In vitro assessment of microbial growth kinetics (Staphylococcus epidermidis, Candida albicans, Klebsiella aerogenes, Escherichia coli) in TPN solutions with and without lipid emulsion.
- Evaluation of the effect of cell physiological state (starved vs. unstarved) on microbial growth.
- Microbiological surveillance of TPN fluids and administration sets in an clinical setting.
Main Results:
- Lipid addition significantly promoted the growth of Staphylococcus epidermidis, reaching high concentrations within 24 hours.
- Candida albicans exhibited slower growth in lipid-containing TPN but still reached significant levels.
- Klebsiella aerogenes grew well in all TPN formulations, while Escherichia coli showed no growth.
- Microbial contamination (coagulase-negative staphylococci, diphtheroids) was detected in 8.2% of TPN systems examined in the infant surgical unit.
Conclusions:
- Lipid-containing TPN solutions can support the growth of clinically relevant microorganisms like Staphylococcus epidermidis, increasing the risk of TPN-associated infections.
- The findings highlight the importance of strict aseptic techniques and monitoring for microbial contamination in TPN administration.
- Further research into strategies to mitigate microbial growth in lipid-based TPN is warranted.