Bacterial isolates from positive paired venous catheter and peripheral blood cultures taken during parenteral nutrition were the same species but different strains: A case report.

OBJECTIVE: The same microbial species isolated from blood simultaneously drawn from a central venous catheter hub and a peripheral vein (paired blood cultures) during parenteral nutrition may be assumed to represent the same strain. This case report provides an example of this assumption being incorrect along with a comparator example of it being correct. This has implications for interpretation of differential time to positivity and differential quantitative blood cultures during investigation of suspected intraluminal intravascular catheter or cannula bloodstream infection. CASE DESCRIPTION: Two patients ages ≥18 y prescribed parenteral nutrition each had positive paired blood cultures that had been taken for suspected catheter bloodstream infection because of temperature spikes ≥38°C. The paired Staphylococcus epidermidis isolates from the first patient and the paired Enterococcus faecium isolates from the second patient were each tested beyond routine clinical care to establish if they could be different strains. The central and peripheral isolates of Staphylococcus epidermidis from the first patient were different strains based on hospital-reported antibiograms, genomic DNA profiles, thermograms, and weaker growth and different sizes of colonies of the central strain compared with the peripheral strain. There were no such differences for the isolates of Enterococcus faecium from the second patient. RESULTS: The central and peripheral isolates of Staphylococcus epidermidis from the first patient were different strains based on hospital-reported antibiograms, genomic DNA profiles, thermograms, and weaker growth and different sizes of colonies of the central strain compared with the peripheral strain. There were no such differences for the isolates of Enterococcus faecium from the second patient. CONCLUSION: This case report indicates consideration should be given to reporting whether bacteria have been identified at either species or strain level if differential time to positivity or differential quantitative blood cultures are used to define catheter or cannula bloodstream infection.

Contribution of intravenous medication to water and sodium intake in upper and lower gastrointestinal surgical patients.

OBJECTIVES: The quantitative importance of prescribed intravenous (IV) medication to water and sodium intake in routine clinical practice is undocumented, with uncertain influence on clinical outcomes. The present study aimed to redress this issue in surgical patients with gastrointestinal problems. METHODS: The prescription and administration of IV medication and fluids were retrospectively reviewed for water and sodium over 24-h periods in 86 patients in upper and lower gastrointestinal surgical wards in two teaching hospitals. Changes over 5 y were assessed in the same two wards using the same methodology. RESULTS: Among 90.7% of patients prescribed IV medication, the median intake was 272 mL water/d (range, 40-2687 mL water/d) and 27 mmol sodium/d (range, 2-420 mmol sodium/d), with no significant difference between hospitals or ward type. In 28.2% of patients receiving any infusates, the only source of water and sodium was IV medication, and in 14.3% of patients, the medication provided more sodium than other infusates. Antibiotic agents and paracetamol accounted for 58.3% of water and 52.3% of sodium in IV medication. Historic data of IV medicine-related water and sodium intake did not differ significantly from current data. The literature suggests that clinical outcomes can be modulated by variations in water and sodium intake well within the range provided by IV medication. CONCLUSION: IV medicine prescriptions, particularly antibiotic agents and paracetamol, can make substantial and clinically relevant contributions to daily water and sodium intake. These contributions have persisted over time and should be considered during routine assessments of fluid balance and interventions aiming to improve clinical outcomes.

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.

BACKGROUND & AIMS: 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. METHODS: C. albicans growth was assessed in quadruplicate in 12 PN infusates, with and without lipid and varying glucose concentrations. RESULTS: 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). CONCLUSIONS: 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.

Factors that influence Staphylococcus epidermidis growth in parenteral nutrition with and without lipid emulsion: a study framework to inform maximum duration of infusion policy decisions.

BACKGROUND & AIMS: Recommendations limit infusion of parenteral nutrition (PN) from bags with lipid to 24 h (48 h if lipid free) because lipid putatively encourages contaminant growth. This study aimed to examine these recommendations and identify factors affecting Staphylococcus epidermidis growth in PN. METHODS: S. epidermidis growth was assessed in quadruplicate in 12 PN regimens, with and without lipid and varying glucose concentrations. RESULTS: Baseline colony forming units (cfu)/mL (32.6) less than doubled at 48 h in all infusates. In PN infusates (pH 6.2 + 0.02 (SEM)) growth was independently increased by the presence of 5% w/v lipid (14.2 cfu/mL; P = 0.028), and glucose concentration (25.6 cfu/mL per 10% increase in w/v glucose; P = 0.003). In a separate analysis growth was stimulated by energy density (27.7 cfu/1000 kcal non-nitrogen energy in 2 L; P = 0.002), without a significant effect of % non-protein energy from lipid (-2.6 cfu/ml per 10%). CONCLUSIONS: Using a framework developed to examine growth of potential contaminants in PN, no evidence was found to support the specific recommendation to restrict the maximum infusion duration of lipid containing PN to a greater extent than lipid free PN. S. epidermidis growth was not only affected by the presence of lipid, but also glucose concentration and energy density.