The administration of parenteral nutrition (PN) via central venous catheters (CVVs) is a major source of CR-BSIs. Efforts are continuously being made to identify risk factors that increase this potentially devastating consequence of hyperalimentation so that mitigation strategies may be implemented.
One such risk factor is the macronutrient composition of the PN itself. The administration of IV fat emulsion (IFE) has been associated with an increased infection incidence most likely secondary to the promotion of biofilm formation by common microbes associated with CR-BSIs. Soybean oil IV fat emulsion (SO-IFE) has been found to stimulate Candida albicans biofilm, whereas mixed-oil IV fat emulsion (MO-IFE) has been found to reduce it secondary to the presence of capric acid, which inhibits hyphae formation and elongation of fungal infections. Docosahexaenoic acid and eicosapentaenoic acid are found in MO-IFE but not SO-IFE and may contribute to a reduction in biofilm formation in Staphylococcus aureus (SA) infections.
The purpose of this retrospective cohort study was to compare CR-BSI rates in pediatric patients receiving SO-IFE or MO-IFE while controlling for other factors that can affect risk.
This study included pediatric patients who received PN at a Memphis children’s hospital (i.e., those in the cardiovascular, neonate, or pediatric ICUs) or at an outpatient children’s intestinal rehabilitation clinic. Pediatric patients were enrolled in the study if they were inpatients or outpatients between January 1, 2015, and July 31, 2019. Investigators calculated days of exposure in those aged 18 years or older who had a CVV placed for PN administration and who received IV IFE for at least 3 times a week for at least 7 days.
The presence of a CR-BSI was identified by a positive blood culture with no other identifiable source of infection and by the use of antibiotics for at least 7 days. Inpatients received IFE separately with amino acids and dextrose in a two-in-one solution, whereas outpatients received an admixture of all three macronutrients. Ethanol lock therapy, which is used to prevent and eradicate CVV infections, was employed in outpatients. Exposure was monitored until the IFE was discontinued. If patients received both SO-IFE and MO-IFE, CR-BSI data were recorded separately for each formulation. Particular infectious sources of CR-BSIs studied included C albicans, non-albicans Candida spp (NAC), coagulase-negative Staphylococcus (CoNS), Enterobacterales, Enterococcus spp, methicillin-resistant SA, and Pseudomonadales.
The primary outcome were the categorical and total CR-BSI rates between the IFE formulations.
There was a total of 743 exposures for SO-IFE and 450 exposures for MO-IFE among the 1,131 patients, resulting in 32,599 and 19,796 days of therapy, respectively. Sixty-two patients received both SO-IFE and MO-IFE with a subtotal of 12,490 days for SO-IFE and 8,696 days for MO-IFE. Approximately two-thirds of the patients were neonates (i.e., younger than age 28 days, 67% for SO-IFE, and 61.6% for MO-IFE). The overall infection rate was 6.27/1,000 fat emulsion days. The most common infections were due to CoNS, Enterobacterales, and SA. The majority of polymicrobial infections (80%) occurred in the SO-IFE group.
The average rate of infection with CoNS was significantly higher in the SO-IFE group than in the MO-IFE group (3.58/1,000 days and 1.39/1,000 days, respectively; incidence rate ratio [IRR] 0.27: 95% CI; 0.16-0.46, P <.01). The total average rates of infections were also higher in the SO-IFE group than in the MO-IFE group (7.33/1,000 days and 4.52/1,000 days, respectively; IRR 0.60: 95% CI, 0.44-0.81, P <.01).
Fewer total CR-BSIs were significantly associated with being a child (vs. a neonate, infant, or adolescent; IRR 0.49, P = .03), male gender (IRR 0.75, P = .02), and receiving outpatient PN (IRR 0.67, P = .03). Patients who received MO-IFE were 73% less likely to have a CoNS C-BSI (IRR 0.27, P <.01) and 40% less likely to experience any CR-BSI (IRR 0.60, P <.01) than those who received SO-IFE.
The authors cautioned that additional confounders may have contributed to the results than what they had identified in this single-center study since CoNS was the only pathogen that demonstrated a statistically significant difference between the two IV IFE formulations.
As pharmacists are involved in consulting on hyperalimentation and in compounding PNs, this paper provides valuable preliminary information on the different clinical outcomes in pediatric patients between the use of MO-IFE and SO-IFE formulations, with results favoring the former product.
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