The potential for isothermal microcalorimetry to detect venous catheter infection isolates and establish antibiograms.

OBJECTIVES: Because bloodstream infection and venous catheter (or cannula) bloodstream infection are associated with high morbidity and cost, early identification and treatment are important. Isothermal microcalorimetry can detect microbial growth using thermal power (heat flow), essentially in real time. The aim of this study was to examine the potential of this technique in clinical practice. METHODS: Thermal power of wild-type bacteria (Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae, and Enterococcus faecium) isolated from blood cultures of adult inpatients receiving parenteral nutrition in routine clinical practice was measured at 37°C every 10s using a Thermometric 2277 instrument. Temporal patterns of heat flow were used to detect the presence of bacteria, differentiate between them, and test their antibiotic sensitivity. Within and between batch reproducibility (% coefficient of variation [%CV]) was also established. RESULTS: Isothermal microcalorimetry always correctly detected the absence or presence of wild-type bacteria. Thermograms differed distinctly between species. Key thermographic features, such as peak heights, timing of peak heights, and interval between peak heights, were highly reproducible within each species (within-batch %CV usually about ≤1%, although between-batch %CV was usually higher). The antibiotic sensitivities (tested only for S. epidermidis and K. pneumoniae) confirmed the results obtained from the hospital laboratory. CONCLUSIONS: Isothermal microcalorimetry is a promising and highly reproducible real-time measurement technique with potential application to the investigation, species identification, and targeted antibiotic treatment of bloodstream infection and venous catheter (or cannula) bloodstream infection.

Estimating Total Energy Expenditure to Determine Energy Requirements in Free-Living Children With Stage 3 Chronic Kidney Disease: Can a Structured Approach Help Improve Clinical Care?

OBJECTIVE: Malnutrition and obesity are complex burdensome challenges in pediatric chronic kidney disease (CKD) management that can adversely affect growth, disease progression, wellbeing, and response to treatment. Total energy expenditure (TEE) and energy requirements in children are essential for growth outcomes but are poorly defined, leaving clinical practice varied and insecure. The aims of this study were to explore a practical approach to guide prescribed nutritional interventions, using measurements of TEE, physical activity energy expenditure (PAEE), and their relationship to kidney function. DESIGN AND METHODS: In a cross-sectional prospective age-matched and sex-matched controlled study, 18 children with CKD (6-17 years, mean stage 3) and 20 healthy, age-matched, and gender-matched controls were studied. TEE and PAEE were measured using basal metabolic rate (BMR), activity diaries and doubly labeled water (healthy subjects). Results were related to estimated glomerular filtration rate (eGFR). The main outcome measure was TEE measured by different methods (factorial, doubly labeled water, and a novel device). RESULTS: Total energy expenditure and PAEE with or without adjustments for age, gender, weight, and height did not differ between the groups and was not related to eGFR. TEE ranged from 1927 ± 91 to 2330 ± 73 kcal/d; 95 ± 5 to 109 ± 5% estimated average requirement (EAR), physical activity level (PAL) 1.52 ± 0.01 to 1.71 ± 0.17, and PAEE 24 to 34% EAR. Comparisons between DLW and alternative methods in healthy children did not differ significantly, except for 2 (factorial methods and a fixed PAL; and the novel device). CONCLUSION: In clinical practice, structured approaches using supportive evidence (weight, height, BMI sds), predictive BMR or TEE values and simple questions on activity, are sufficient for most children with CKD as a starting energy prescription.

Comparative effect of seven prophylactic locks to prevent biofilm biomass and viability in intravenous catheters.

BACKGROUND: Patients requiring long-term intravenous access are at risk of intraluminal catheter bloodstream infection. 'Prophylactic' locks aim to limit this risk but there is uncertainty regarding the most effective lock. OBJECTIVES: To develop a novel technique intended to replicate clinical procedures to compare the effectiveness of various 'prophylactic' locks against biofilm biomass ('biomass') formation and biofilm viability ('viability') of Escherichia coli and Staphylococcus epidermidis in intravenous catheters. METHODS: For 10 consecutive days 106 cfu/mL E. coli NCTC 10418 and S. epidermidis ATCC 12228 were separately cultured in single lumen 9.6 French silicone tunnelled and cuffed catheters. These were flushed with 0.9% w/v sodium chloride using a push-pause technique before and after instillation of seven 'prophylactic' locks (water, ethanol, sodium chloride, heparinized sodium chloride, citrate, taurolidine plus citrate, and taurolidine; each in triplicate) for 6 h daily. Intraluminal 'biomass' and 'viability' were quantified using crystal violet staining and flush culture, respectively. RESULTS: The reduction of 'biomass' and 'viability' depended on both agent and species. Citrate was least effective against E. coli 'viability' and 'biomass' but most effective against S. epidermidis 'viability', and taurolidine was most effective against E. coli 'biomass' and 'viability' but least effective against S. epidermidis 'viability'. 'Biomass' and 'viability' were significantly correlated in E. coli between (r = 0.997, P < 0.001) and within (r = 0.754, P = 0.001) interventions, but not in S. epidermidis. CONCLUSIONS: A novel technique found the effect of 'prophylactic' agents in reducing 'biomass' and 'viability' varied by species. The choice of agent depends on the most likely infecting organism.

An evidence-based surveillance tool to identify and report catheter/cannula bloodstream infection in patients receiving parenteral nutrition.

OBJECTIVE: Catheter/cannula-bloodstream infection (CBI) has been proposed as a marker of the quality of care provided to patients receiving parenteral nutrition (PN). However, surveillance criteria for CBI are variable, inconsistent, and sometimes confusing and impractical. Surveillance criteria were developed to simply and accurately demonstrate the presence or absence of CBI. The aim of this study was to establish a simple and valid surveillance tool, with consideration of changes in vital signs, to identify CBI in patients receiving PN. METHODS: Adult (≥18 y) inpatients prescribed PN at a single large teaching hospital were recruited between October 11, 2017 and November 16, 2018. Common clinical and laboratory criteria, including blood culture, associated with 100 consecutive PN episodes associated with suspected CBI were examined for potential predictive markers of CBI. Using binary logistic regression, criteria were incorporated into an instrument that was validated against a reference classification of CBI established by an expert multidisciplinary group. RESULTS: The reference classification comprised 12 PN episodes with CBI and 88 without. Abnormal vital signs did not significantly predict CBI, but resolution of fever (≥38°C) and low systolic blood pressure (<100 mm Hg) in response to a specific treatment for CBI (line removal/antibiotics) did. Two other criteria were also significant predictors: positive blood culture; and absence of an alternative source that could explain the septic episode other than the catheter/cannula supplying PN. These two criteria together with a positive response to treatment (temperature and/or blood pressure, incorporated into a single binary variable), resulted in 100% correct CBI classification (100% sensitivity, 100% specificity, and 1.000 area under the curve in receiver operating characteristic analysis). All criteria could be retrospectively extracted from the medical records of all PN episodes. CONCLUSION: A CBI tool shows promise as a surveillance instrument for benchmarking and interinstitutional comparisons of the care received by hospitalized patients given PN.

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.

Nutritional self-screening in <1 min: Evaluation of a measuring station using sonic measurement of height.

OBJECTIVE: Since nutritional screening is not routinely and accurately performed by busy care workers, the aim of this study was to evaluate a self-screening electronic measuring station that includes sonic height measurements. METHODS: In all, 114 patients, 18 to 85 y of age and attending gastrointestinal outpatient clinics, followed automatically triggered audio-recorded instructions for weight and height measurements. The patients also provided information about unintentional weight loss to establish malnutrition risk using the Malnutrition Universal Screening Tool (MUST). In 56 healthy individuals, the effect of head/foot positions on height was examined using video-recordings. Laboratory studies examined the effects of hair/wigs, the position of a skull and horizontal plates and ambient conditions. Measurements were also made on a mechanical machine for comparison. RESULTS: Of the patients, 21.9% were malnourished, with 99% agreement between sonic and mechanical machine categorization. Patients self-screened in only 35.6 ± 14.8 s (median 32 s) and 77% rated the screening as very easy (22%, easy), despite encountering some remediable snags. Within-subject precision for height was 0.186 cm in healthy individuals and 0.368 cm in patients. Humidity and barometric pressure had negligible/undetectable effects on height measurements, but temperature corrections were confounded by calibration errors. In the most lateral standing positions, height was underestimated curvilinearly. In healthy individuals, height measurements were 0.353 ± 0.542 cm lower on the sonic than mechanical device, which was inadequately explained by standing position or body tilt, although hair was found to be "invisible" only to the sonic machine. CONCLUSION: A method has been developed to rapidly and reliably self-screen for malnutrition using MUST, avoiding calculation and categorization errors, while providing results that can be immediately printed or transmitted electronically into patient notes.

'Self-screening' for malnutrition with an electronic version of the Malnutrition Universal Screening Tool ('MUST') in hospital outpatients: concurrent validity, preference and ease of use.

Self-screening using an electronic version of the Malnutrition Universal Screening Tool ('MUST') has been developed but its implementation requires investigation. A total of 100 outpatients (mean age 50 (sd 16) years; 57 % male) self-screened with an electronic version of 'MUST' and were then screened by a healthcare professional (HCP) to assess concurrent validity. Ease of use, time to self-screen and prevalence of malnutrition were also assessed. A further twenty outpatients (mean age 54 (sd 15) years; 55 % male) examined preference between self- screening with paper and electronic versions of 'MUST'. For the three-category classification of 'MUST' (low, medium and high risk), agreement between electronic self-screening and HCP screening was 94 % (κ=0·74, se 0·092; P<0·001). For the two-category classification (low risk; medium+high risk) agreement was 96 % (κ=0·82, se 0·085; P<0·001), comparable with the previously reported paper-based self-screening. In all, 15 % of patients categorised themselves 'at risk' of malnutrition (5 % medium, 10 % high). Electronic self-screening took 3 min (sd 1·2 min), 40 % faster than previously reported for the paper-based version. Patients found the tool easy or very easy to understand (99 %) and complete (98 %). Patients that assessed both tools found the electronic tool easier to complete (65 %) and preferred it (55 %) to the paper version. Electronic self-screening using 'MUST' in a heterogeneous group of hospital outpatients is acceptable, user-friendly and has 'substantial to almost-perfect' agreement with HCP screening. The electronic format appears to be as agreeable and often the preferred format when compared with the validated paper-based 'MUST' self-screening tool.

Influence of deprivation on health care use, health care costs, and mortality in COPD.

BACKGROUND AND AIM: Deprivation is associated with the incidence of COPD, but its independent impact on clinical outcomes is still relatively unknown. This study aimed to explore the influence of deprivation on health care use, costs, and survival. METHODS: A total of 424 outpatients with COPD were assessed for deprivation across two hospitals. The English Index of Multiple Deprivation (IMD) was used to establish a deprivation score for each patient. The relationship between deprivation and 1-year health care use, costs, and mortality was examined, controlling for potential confounding variables (age, malnutrition risk, COPD severity, and smoking status). RESULTS: IMD was significantly and independently associated with emergency hospitalization (ß-coefficient 0.022, SE 0.007; p=0.001), length of hospital stay, secondary health care costs (ß-coefficient £101, SE £30; p=0.001), and mortality (HR 1.042, 95% CI 1.015-1.070; p=0.002). IMD was inversely related to participation in exercise rehabilitation (OR 0.961, 95% CI 0.930-0.994; p=0.002) and secondary care appointments. Deprivation was also significantly related to modifiable risk factors (smoking status and malnutrition risk). CONCLUSION: Deprivation in patients with COPD is associated with increased emergency health care use, health care costs, and mortality. Tackling deprivation is complex; however, strategies targeting high-risk groups and modifiable risk factors, such as malnutrition and smoking, could reduce the clinical and economic burden.

Cost-effectiveness of oral nutritional supplements in older malnourished care home residents.

BACKGROUND & AIMS: Malnutrition is common in care home residents, but information on the cost-effectiveness of nutritional interventions is lacking. This study, involving a randomised trial in care home residents, aimed to examine whether oral nutritional supplements (ONS) are cost-effective relative to dietary advice. METHODS: An incremental cost-effectiveness analysis was undertaken prospectively in 104 older care home residents (88 ± 8 years) without overt dementia, who were randomised to receive either ONS or dietary advice for 12 weeks. Costs were estimated from resource use and quality adjusted life years (QALYs) from health-related quality of life, assessed using EuroQoL (EQ-5D-3L, time-trade-off) and mortality. The incremental cost-effectiveness ratio (ICER) was calculated using 'intention to treat' and 'complete case' analyses. RESULTS: The ONS group gained significantly more QALYs than the dietary advice group at significantly greater costs. The ICER (extra cost per QALY gained), adjusted for nutritional status, type of care, baseline costs and quality of life, was found to be £10,961 using the 'intention to treat' analysis (£190.60 (cost)/0.0174 (QALYs); n = 104) and £11,875 using 'complete case' analysis (£217.30/0.0183; n = 76) (2016 prices). Sensitivity analysis based on 'intention to treat' data indicated an 83% probability that the ICER was ≤£20,000 and 92% that it was ≤£30,000. With the 'complete case data' the probabilities were 80% and 90% respectively. CONCLUSION: This pragmatic randomised trial involving one of the oldest populations subjected to a cost-utility analysis, suggests that use of oral nutritional supplements in care homes are cost-effective relative to dietary advice.

Defining, Recognizing, and Reporting Malnutrition.

Although malnutrition is a common health and social care problem, there is no universal agreement about its definition, prevalence, or method of identification and report. Fifteen definitions of malnutrition were critically examined to assess their variability. They ranged from descriptions of undernutrition alone to under- and overnutrition, with intakes ranging from dietary protein and energy alone to dietary and nondietary sources of all nutrients and energy. Definitions also varied from non-outcome based to those based on functional, physiological, and/or clinical outcomes. Some definitions relied on the pathways by which malnutrition develops, with one apparently requiring loss of fat-free mass. Also examined were nutrition screening tools, diversely developed for detection of malnutrition, management of malnutrition, and prediction of clinical outcomes or health care usage. Their intended use also varied from specific care settings (hospital, community, care homes) to all settings and from specific age groups to all age groups. With all these definitions and tools, there is considerable scope for confusion and misunderstanding. Therefore, to clarify the burden and significance of malnutrition, guidelines for documenting it in routine practice and reporting it in scientific literature are provided.

Oral nutritional supplements in a randomised trial are more effective than dietary advice at improving quality of life in malnourished care home residents.

BACKGROUND & AIMS: Few trials have explored the effect of nutrition support on quality of life (QoL). This study examined the effects of oral nutritional supplements (ONS) vs dietary advice on QoL in malnourished care home residents. METHODS: 104 malnourished, care home residents (medium + high risk), identified using the Malnutrition Universal Screening Tool ('MUST'), (mean age 88.5 ± 7.9y) were randomised to receive either oral nutritional supplements (ONS) (n = 53) or dietary advice (n = 51) for 12 weeks. Dietary intake was measured using 24 h dietary recall, and QoL assessed using EuroQol (EQ-5D), including time trade off (TTO) (range -0.59 to 1) and visual analogue scale (VAS) (score 0 to 100) for self-perceived health. RESULTS: QoL (adjusted for baseline QOL, malnutrition risk, type of care received (nursing or residential)) was significantly higher in the ONS than the dietary advice group (intention to treat analysis at week 12; n = 104 ). EQ-5D TTO scores (mean ± SE) were 0.50 ± 0.04 vs 0.36 ± 0.05 (P = 0.005), VAS rescaled scores were 0.54 + 0.03 vs 0.046 + 0.03 (P = 0.006) and VAS scores were 61.3 ± 4.5 vs 54.6 ± 6.3 (P = 0.533) for ONS vs dietary advice respectively. Total energy, protein and the majority of micronutrient intakes were significantly greater in the ONS group, with energy intake being 423 kcal greater in the ONS than the dietary advice group at week 12. CONCLUSIONS: This study in malnourished care home residents indicates that ONS can improve QoL and nutritional intake more effectively than dietary advice alone. CLINICAL TRIAL REGISTRY: This trial was registered with clinicaltrials.gov on 10th August 2007. Clinical trials identifier is NCT00515125http://www.clinicaltrials.gov/ct2/show/NCT00515125?term=nutrition+support&rank=60.

Meta-analysis is not enough: The critical role of pathophysiology in determining optimal care in clinical nutrition.

Evidence based medicine has preferably been based on prospective randomized controlled trials (PRCT's) and subsequent meta-analyses in many fields including nutrition and metabolism. These meta-analyses often yield convincing, contradictory or no proof of effectiveness. Consequently recommendations and guidelines of varying validity and quality have been published, often failing to convince the medical, insurance and government worlds to support nutritional care. Causes for lack of adequate proof of effectiveness are manifold. Many studies and meta-analyses lacked pathophysiological depth in design and interpretation. Study populations were not homogenous and endpoints not always clearly defined. Patients were included not at nutritional risk, unlikely to benefit from nutritional intervention. Others received nutrients in excess of requirements or tolerance due to organ failure. To include all available studies in a meta-analysis, study quality and homogeneity were only assessed on the basis of formal study design and outcome rather than on patient characteristics. Consequently, some studies showed benefit but included patients suffering harm, other studies were negative but contained patients that benefited. Recommendations did not always emphasize these shortcomings, confusing the medical and nutritional community and creating the impression that nutritional support is not beneficial. Strong reliance on meta-analyses and guidelines shifts the focus of education from studying clinical and nutritional physiology to memorizing guidelines. To prevent or improve malnutrition more physiological knowledge should be acquired to personalize nutritional practices and to more correctly value and evaluate the evidence. This also applies to the design and interpretation of PRCT's and meta-analyses.

Basal metabolic rate in children with chronic kidney disease and healthy control children.

BACKGROUND: Meeting energy requirements of children with chronic kidney disease (CKD) is paramount to optimising growth and clinical outcome, but little information on this subject has been published. In this study, we examined basal metabolic rate (BMR; a component of energy expenditure) with the aim to determine whether it is related to kidney function independently of weight, height and lean body mass (LBM). METHODS: Twenty children with CKD and 20 healthy age- and gender-matched control children were studied on one occasion. BMR was measured by indirect open circuit calorimetry and predicted by the Schofield equation. Estimated glomerular filtration rate (eGFR) was related to BMR and adjusted for weight, height, age and LBM measured by skinfold thickness. RESULTS: The adjusted BMR of children with CKD did not differ significantly from that of healthy subjects (1296 ± 318 vs.1325 ± 178 kcal/day; p = 0.720). Percentage of predicted BMR also did not differ between the two groups (102 ± 12% vs. 99 ± 14%; p = 0.570). Within the CKD group, eGFR (mean 33.7 ± 20.5 mL/min/m(2)) was significantly related to BMR (ß 0.3, r = 0.517, p = 0.019) independently of nutritional status and LBM. CONCLUSIONS: It seems reasonable to use estimated average requirement as the basis of energy prescriptions for children with CKD (mean CKD stage 3 disease). However, those who were sicker had significantly lower metabolic rates.

Imposed rate and extent of weight loss in obese men and adaptive changes in resting and total energy expenditure.

OBJECTIVES: Weight loss (WL) is associated with a decrease in total and resting energy expenditure (EE). We aimed to investigate whether (1) diets with different rate and extent of WL determined different changes in total and resting EE and if (2) they influenced the level of adaptive thermogenesis, defined as the decline in total or resting EE not accounted by changes in body composition. METHODS: Three groups of six, obese men participated in a total fast for 6 days to achieve a 5% WL and a very low calorie (VLCD, 2.5 MJ/day) for 3 weeks or a low calorie (LCD, 5.2 MJ/day) diet for 6 weeks to achieve a 10% WL. A four-component model was used to measure body composition. Indirect calorimetry was used to measure resting EE. Total EE was measured by doubly labelled water (VLCD, LCD) and 24-hour whole-body calorimetry (fasting). RESULTS: VLCD and LCD showed a similar degree of metabolic adaptation for total EE (VLCD = -6.2%; LCD = -6.8%). Metabolic adaptation for resting EE was greater in the LCD (-0.4 MJ/day, -5.3%) compared to the VLCD (-0.1 MJ/day, -1.4%) group. Resting EE did not decrease after short-term fasting and no evidence of adaptive thermogenesis (+0.4 MJ/day) was found after 5% WL. The rate of WL was inversely associated with changes in resting EE (n = 30, r = 0.-42, p=0.01). CONCLUSIONS: The rate of WL did not appear to influence the decline in total EE in obese men after 10% WL. Approximately 6% of this decline in total EE was explained by mechanisms of adaptive thermogenesis.

Which screening method is appropriate for older cancer patients at risk for malnutrition?

The risk for malnutrition increases with age and presence of cancer, and it is particularly common in older cancer patients. A range of simple and validated nutrition screening tools can be used to identify malnutrition risk in cancer patients (e.g., Malnutrition Screening Tool, Mini Nutritional Assessment Short Form Revised, Nutrition Risk Screening, and the Malnutrition Universal Screening Tool). Unintentional weight loss and current body mass index are common components of screening tools. Patients with cancer should be screened at diagnosis, on admission to hospitals or care homes, and during follow-up at outpatient or general practitioner clinics, at regular intervals depending on clinical status. Nutritional assessment is a comprehensive assessment of dietary intake, anthropometrics, and physical examination often conducted by dietitians or geriatricians after simple screening has identified at-risk patients. The result of nutritional screening, assessment and the associated care plans should be documented, and communicated, within and between care settings for best patient outcomes.

Can trained volunteers make a difference at mealtimes for older people in hospital? A qualitative study of the views and experience of nurses, patients, relatives and volunteers in the Southampton Mealtime Assistance Study.

BACKGROUND: Malnutrition is common amongst hospitalised older patients and associated with increased morbidity and mortality. Poor dietary intake results from factors including acute illness and cognitive impairment but additionally patients may have difficulty managing at mealtimes. Use of volunteers to help at mealtimes is rarely evaluated. OBJECTIVES: To obtain multiple perspectives on nutritional care of older inpatients, acceptability of trained volunteers and identify important elements of their assistance. DESIGN: A qualitative study 1 year before and after introduction of volunteer mealtime assistants on one ward and parallel comparison with a control ward in a Medicine for Older People department at a UK university hospital. PARTICIPANTS AND METHODS: Semi-structured interviews and focus groups, in baseline and intervention years, with purposively sampled nursing staff at different levels of seniority; patients or close relatives; and volunteers. RESULTS: At baseline staff felt under pressure with insufficient people assisting at mealtimes. Introducing trained volunteers was perceived by staff and patients to improve quality of mealtime care by preparing patients for mealtimes, assisting patients who needed help, and releasing nursing time to assist dysphagic or drowsy patients. There was synergy with other initiatives, notably protected mealtimes. Interviews highlighted the perceived contribution of chronic poor appetite and changes in eating patterns to risk of malnutrition. CONCLUSIONS: Improved quality of mealtime care attributed to volunteers' input has potential to enhance staff morale and patients'/relatives' confidence. A volunteer mealtime assistance scheme may work best when introduced in context of other changes reflecting commitment to improving nutrition. IMPLICATIONS FOR PRACTICE: (i) A mealtime assistance scheme should incorporate training, supervision and support for volunteers; (ii) Good relationships and a sense of teamwork can develop between wards staff and volunteers; (iii) Impact may be maximised in the context of 'protected mealtimes'.

Factors Influencing Escherichia coli and Enterococcus durans Growth in Parenteral Nutrition With and Without Lipid Emulsion to Inform Maximum Duration of Infusion Policy Decisions.

BACKGROUND: Recommendations effectively restrict the infusion duration of lipid-containing parenteral nutrition (PN) from a single bag, purportedly because it encourages growth of potential microbial contaminants more than lipid-free PN. Since other variables, including osmolarity, may independently affect microbial growth, this study examined variables affecting growth of Escherichia coli and Enterococcus durans in PN infusates. MATERIALS AND METHODS: Growth of E coli and E durans was assessed in quadruplicate in 12 different PN infusates, with and without lipid, in varying glucose concentrations. RESULTS: Results are presented as mean log10 colony-forming units (cfu)/mL ± SEM at 48 hours. The log10cfu/mL of both E coli and E durans in PN increased considerably after adjustment for baseline log10cfu/mL and pH, from 1.093 to 2.241 (P < .001) and from 0.843 to 3.451 (P < .001) respectively. Growth of each microorganism was independently increased by lipid inclusion, or increasing the proportion of nonnitrogen energy from lipid, and reduced by raising the glucose concentration or energy density. Increasing the osmolarity of lipid-PN with glucose or sodium chloride reduced growth but only significantly for sodium chloride (E coli, P = .025; E durans, P = .045). Induced changes in pH affected the growth of the 2 organisms differently. CONCLUSION: The presence of lipid and an increasing proportion of energy from lipid in PN favored the growth of E coli and E durans. Osmolarity changes and the nutrient type causing these changes independently affect the growth of these microbes. Each effect needs to be considered when establishing guidelines based on the growth of potential contaminants in different types of PN.