Factors influencing Candida albicans growth in parenteral nutrition with and without lipid emulsion: Using an established framework to inform maximum duration of infusion policy decisions

Abstract

Because lipid putatively encourages contaminant growth it has been proposed that infusion of lipid-containing parenteral nutrition (PN) bags should be restricted to 24 h (48 h or longer if lipid free). This study aimed to examine this proposal by identifying factors affecting Candida albicans growth in PN. C. albicans growth was assessed in quadruplicate in 12 PN infusates, with and without lipid and varying glucose concentrations. The results are presented as mean ± SEM. Baseline log10 colony forming units (cfu)/mL (1.806 ± 0.015) increased substantially by 48 h in the PN infusates (to 3.731 ± 0.059). In PN infusates (pH 6.14 ± 0.01) growth was unaffected by the presence of 5% w/v lipid (0.246 ± 0.156 log10 cfu/mL decrease; P = 0.127), and independently suppressed by increasing glucose concentration (0.438 ± 0.174 log10 cfu/mL decrease per 10% increase in w/v glucose; P = 0.018). In a separate analysis growth was suppressed by increasing energy density (0.520 ± 0.179 log10 cfu/mL decrease per 1000 kcal non-nitrogen energy in 2 L; P = 0.007), without a significant effect of % non-nitrogen energy from lipid (0.056 ± 0.036 log10 cfu/ml increase per 10%; P = 0.082). Using a framework developed to examine growth of potential contaminants in PN, the inclusion of lipid emulsion in PN produced no specific effect on the growth of C. albicans, other than by increasing energy density. Growth was independently suppressed by increasing either glucose concentration or non-nitrogen energy density.