Risks of microbiological contamination of enteral feeds during the set up of enteral feeding systems

Four enteral feeding systems were compared in terms of their ability to limit the chance of introducing microbial contamination during the set up of the systems. The systems incorporated a variety of containers and giving sets, thus resulting in different methods of assembly. The systems were tested under ward conditions in two hospitals and under the worst possible conditions in a simulated ward study. The Steriflo system performed best. Even in the worst possible situation, counts remained very low and the number of Steriflo feeds remaining sterile throughout the feeding period was more than 85% ( P < 0.05). The Bag system performed worst: at the end of the recommended feeding period counts of more than 1000 colony forming units/ml were obtained and the number of sterile feeds was significantly lower than for the other systems ( P < 0.05). Crown cork bottle and Container performed equally well, but not as well as the Steriflo system. Taking <100 micro-organisms/ml as a criterion, the differences however were not statistically significant.
Decanting of sterile feeds was shown to impose a risk of introducing microbial contaminants to enteral feeds. This however was shown to be strongly dependent on the system design.
The results obtained in the hospital trials clearly show that enteral feeding systems can be set up safely when hygienic procedures are followed carefully. When systems were handled with contaminated hands, as simulated in a laboratory trial, the chance of introducing microbial contamination in the feeds increases significantly. Taking into account that hygienic procedures are not always adhered to in hospitals, it is concluded that the Steriflo system offers the best chance, compared with other currently available systems, that enteral feeds will remain microbiologically safe throughout feeding. Practical implications of these findings are discussed.     

Home enteral tube feeding in patients with inherited metabolic disorders: safety issues

BACKGROUND: Many children with inherited metabolic disorders (IMD), at risk of hypoglycaemia and metabolic decompensation, are dependent on long-term home overnight enteral tube feeding but its safety issues have not been evaluated. OBJECTIVE: To identify common safety issues and carer pressures for patients with IMD on home enteral tube feeds (HETF). METHODS: Thirty-four patients (53% male; median age 4.1, range: 1.2-15.8 years), with IMD on home continuous overnight tube feeds were recruited. They were all following specialized feeding regimens. A questionnaire, administered by face-to-face interview with carers identified family members involved in feeding, training they received; child safety issues; equipment reliability and carer night time disturbance. RESULTS: The principal problems were: carer sleep disturbance (100%); tube entanglement (71%); untrained secondary carers (71%); faulty pumps (50%); tube blockages (45%); faulty equipment (32%); and child tampering with pumps and feeding equipment (29%). CONCLUSIONS: Significant risks for children on HETF with IMD were identified, potentially leading to metabolic decompensation and hospitalization. The safety of feeding equipment, lack of training of extended family members and practical support for carers requires urgent attention.     

Endogenous bacterial contamination of enteral tube feeding systems during administration of feeds to hospital patients

The use of sterile, prepackaged enteral feeds has helped to reduce the risk of exogenous microbial contamination of enteral feeds but there is increasing evidence that endogenous contamination with bacteria from the patient's own flora may occur. The purpose of this study was to compare the levels and types of micro-organisms present in residual feed in nutrient containers and giving sets when either 500 or 1000 ml prefilled, ready-to-hang nutrient containers were used to administer 1000 and 2000 ml quantities of feed to patients on hospital wards over 24 h using a single giving set over this period. Forty-one adult patients were randomly allocated to receive either 1000 or 2000 ml of sterile undiluted, whole protein feed over 24 h from 1000 ml prefilled containers (Nutrison Steriflo, Cow and Gate Nutricia Ltd) or from 500 ml prefilled bottles (Osmolite, Abbott Laboratories Ltd). One giving set was used over 24 h for each patient. Samples of feed from the nutrient containers and the distal end of each giving set were sent for microbiological analysis immediately after removal from the patient. Control experiments demonstrated that there were no micro-organisms in the unopened feed containers and that none was introduced during the feed sampling procedure. The percentage of days on which feed samples from the nutrient containers were contaminated was $lt; 10% for feeds administered at a rate of 1000 ml over 24 h and $lt; 23% for those administered at a rate of 2000 ml over 24 h irrespective of system, which may be attributed to increased handling of systems and reuse of the giving set. However, the percentage of days on which samples from the giving sets were contaminated was 43% for all systems. In fact, on an average of 33% of days it was found that the only feed sample that was contaminated was that collected from the giving set. Counts for these samples were $lt;10³ cfu/ml and the main bacteria isolated included Klebsiella spp., Enterobacter spp., Escherichia coli, Streptococcus faecalis and Pseudomonas aeruginosa. These results further implicate retrograde spread of the patient's own flora as a possible source of microbial contamination of feed in the giving sets of enteral feeding systems.     

Microbiological quality of reconstituted enteral formulations used in hospitals

Contamination of enteral feeds may occur during preparation, storage, decanting, and administration to patients. The aim of this study was to investigate the microbiological quality of reconstituted enteral feeds, residual feeds from feed delivery systems, and the water used to reconstitute powdered feeds in hospital. Hazard Analysis Critical Control Points (HACCP) system was implemented to control microbiological contamination of the enteral feeding formulations. Before the implementation of the HACCP system microbiological analyses of feeds showed the presence of indicator organisms such as coliforms and Enterococcus spp. and unacceptably high levels of mesophilic aerobic microorganisms (>10(4) cfu/mL). After the implementation of the HACCP, the microbial quality of the feeds improved significantly, with counts of <10(1) cfu/mL. Blenders used in reconstituting feeds were found to be the main source of bacterial contamination.     

The effect of handling procedures on bacterial contamination of enteral feeds—importance of design of enteral feeding sets

The level of bacterial contamination introduced into two enteral feed delivery systems with different types of air inlet was compared when the air inlets were touched with bare hands, hands protected by sterile gloves and hands experimentally contaminated with bacteria. Feed and surface samples from the set with a flutter valve air inlet which had a smaller surface area for contact were less contaminated than those from the set with long airway tube. This indicates that the design of the system does have an effect on the level of contamination introduced into feeds during the assembly of feeding sets and the delivery of enteral feed,     

Strategies to Manage Gastrointestinal Symptoms Complicating Enteral Feeding

Diarrhea and abdominal distension are common complications associated with enteral feeding. Often the cause is unknown, the enteral formula is blamed and changes to the mode of delivery or formula are instituted. However, the evidence base for many strategies used is limited. Altering the osmolality and temperature of the formula and/or the rate of infusion are commonly practiced but evidence for their benefit is largely anecdotal. Preventing microbial contamination of the feed is important and clear guidelines exist to achieve this. The formulation itself can be modified. While the addition of fiber is well supported theoretically, outcome data are less convincing. Avoidance of osmotically active, poorly absorbed short‐chain carbohydrates in the formula (often used as the major carbohydrate source) is a new tactic to minimize diarrhea. It has compelling theoretical support, but requires further investigation. A methodical clinical approach to gastrointestinal complications of enteral feeding is warranted and an algorithm for management is proposed.     

More than just a health issue: a review of current issues in the care of enterally-fed children living in the community

There are increasing numbers of children with a disability living in the community who require enteral tube feeds to optimize their nutritional status. Whilst there appears to be evidence of health gains, for some children there may also be serious and unintended social deprivations resulting from the need to be tube fed. This paper reviews the literature on support for children who are tube fed and makes a case for more coordinated and effective support services for families who are tube feeding a child at home. It is argued that national guidance should be developed which clarifies the position of all non-parent carers and staff who are willing to administer enteral tube feeds. Such guidance should also ensure that enterally-fed children have the same rights to educational and social services as other children and that families are given the opportunity to make informed decisions about the implications of enteral feeding prior to it being established.     

Promoting the reuse of enteral feeding equipment in ambulatory patients: Where do we stand?

Cleaning and reuse of single-use and single-patient-use enteral feeding equipment is common in Australia, particularly in ambulatory patients. This practice may result in feed product contamination and adverse clinical outcomes for the patient, and exposes the health professional providing the advice to liability for harm caused. The present article reviews the literature addressing cleaning and reuse of enteral feeding equipment to provide guidance to health professionals managing and supporting patients receiving home enteral nutrition.     

Accuracy of home enteral feed preparation for children with inherited metabolic disorders

Background: Many children with rare chronic disorders require home enteral tube feeds (HETF) consisting of multiple modular ingredients. Feeds are often complex and the risk of errors during their preparation is high. The consequences of over‐ or under‐concentration can be critical. The aim of the present prospective observation study was to assess the accuracy, skills and technique of caregivers when preparing and administering HETF. Methods: Fifty‐two HETF patients (median age 7.5 years, range 0.7–18.0 years) with inherited metabolic disorders (IMD) requiring special feeds were recruited. Using observation and a structured questionnaire, a practical assessment of feed preparation and storage by the main caregiver was undertaken by an independent dietitian and nurse in the child’s home, including hygiene practices, accuracy of measuring recipe ingredients, and storage of both ingredients and prepared feeds. Results: The majority (85%; n = 44) of feeds were based on >1 ingredient (median 3; range 1–6). Almost half (48%; n = 25) of caregivers measured feed ingredients inaccurately. Of the 31% (n = 16) using scoops, 31% used incorrect measuring spoons and 25% did not level scoops appropriately. Some 45% (n = 20/44) of carers measured liquid ingredients inaccurately. Hygiene practices during feed preparation were poor, including a lack of hand washing (31%: n = 16) and incorrect storage procedures for unused feed ingredients (56%; n = 29). Conclusions: Practices in the preparation of modular HETF for children with IMD were not ideal. A combination of inaccuracy, poor hygiene, inappropriate storage, and long feed hanging times increases both metabolic and microbial risk. Better education, regular monitoring and the development of ready‐to‐use or preweighed ingredients would be beneficial.     

Home enteral feeding audit 1 year post-initiation

OBJECTIVE To determine the practical problems that families of children on home enteral tube feeds (HETF) experience in the first year post-hospital discharge. METHODS Thirty parents/carers of children (0-16 years) completed a multiple choice/short answer questionnaire by interview 12 months after discharge from hospital. Issues addressed included: home delivery of feed and equipment; pump usage; tube changes; and overnight feeding. RESULTS: The main problems identified were: sleep disturbance (75%); frequent tube dislodgement (46%); tube blockages (41%); inability of some home delivery companies (HDC) to provide all the paediatric special feeds required (43%); and pump inaccuracy (23%). Conclusions Children on long-term HETF and their families experience significant problems with sleep disturbance, tube dislodgement and tube blockage. In addition, accuracy of pumps and obtaining feed and equipment was a source of stress. Dietitians and community nurses urgently need to explore solutions to the common problems associated with overnight feeding. Furthermore, regular home reviews are necessary in long-term HETF to continue to identify and minimize problems.     

Clinical trial of a paediatric enteral feed

A paediatric enteral feed, Paediasure, was given to children aged 1–8 years needing nutritional support. Those who had more than 60% of their energy from Paediasure were included in the trial which ran for 1–3 months. Anthropometric measurements were done at the start and at the end of the trial. Nutritional evaluations of Paediasure were made and compared with other enteral feeds.
It was found that children's growth was satisfactory on Paediasure, that it was well tolerated and palatable if given orally. Paediasure has a high-nutrient density so when given at low volumes (which are required for overweight and some very underweight patients) the recommended nutrient intakes (RNI) are more likely to be met than if other enteral feeds are used.     

A controlled study of the performance of five enteral feeding pumps

The performance of five enteral feeding pumps was investigated in terms of flow volume delivered at selected rate settings using three commercial enteral feeds of differing weight per millilitre values. There were significant differences in the performances of pumps over the range of settings, particularly at levels >100 ml/h with the highest density feed. The mean accuracy of delivery was within ±10% of that expected on all but one occasion. The significance of the observations in relation to possible sources of error is discussed.     

The effect of handling procedures on microbial contamination of enteral feeds--a comparison of the use of sterile vs non-sterile gloves.

The use of non-sterile disposable gloves to reduce the level of microbial contamination introduced into enteral feeds during the assembly of the feeding systems was investigated. No contamination was detected in any of the feed samples collected from the systems assembled wearing non-sterile gloves. The number of microorganisms transferred to the surface of agar plates used for fingerprint cultures was reduced from an average of 43-54 colony forming units (cfu) per plate for volunteers with bare hands to less than 1 cfu when they wore non-sterile gloves. No contamination was detected on plates touched by volunteers wearing sterile gloves.     

Microbiological quality of products used in enteral feeds

The microbiological quality of 19 commonly used nasogastric feeds and feed ingredients was determined. Thirteen of the products yielded no viable micro-organisms while six, all of which were powders containing milk or whey proteins, gave aerobic viable counts from 50-3000 organisms g-1. Possible microbial limits for enteral feeds are discussed with reference to those already suggested for special dietary products, infant formulas and non-sterile pharmaceuticals.     

Application of Hazard Analysis Critical Control Points system to enteral tube feeding in hospital

An HACCP system was implemented for the quality assurance of preparation, storage and delivery of enteral feeds to patients in hospital. Routine methods of feed preparation, storage and delivery to patients were studied and a flow chart was initially made. After identifying hazards, an HACCP team was assembled, a flow chart was modified and critical control points were defined using a decision tree. Control measures for each step of the process and its monitoring and corrective measures to be applied were also defined. In addition, feed samples were analysed for microbiological quality and feed storage temperatures were also recorded, before and after the implementation of the HACCP system. When the control measures were applied and monitored, the hazard was reduced. Bacterial counts in feed were reduced from 10⁵ cfu mL^–1 to < 10¹ cfu mL^–1. The results show that contamination of enteral feed may be reduced or eliminated if a systematic approach such as HACCP is applied effectively.     

The nutritional intake supplied by enteral formulae used in older children (aged 7–12 years) on home tube feeds

Background:  In the UK, patients aged 6–12 years contribute more than one-third of children on home enteral tube feeds (HETF). Many enteral feeds are given to this age group. The present study aimed to investigate the formula with the best nutritional composition for children aged 7–12 years on HETF by comparing the nutrient intake of three feed types; a paediatric feed (PF) for 1–6 year olds, an adult feed (AF), and a feed for children (OCF) aged 7–12 years.
Methods:  Twenty-five HETF children aged 7–14 years (median 10 years) were given a 6.3 kJ mL⁻¹ enteral feed designed for 7–12 year olds (or weighing 21–45 kg) for 9 months. Nutrient intakes on the 7–12-year-old feed were compared with baseline feed (paediatric n  = 10; or adult n  = 15).
Results:  At baseline, the PF failed to meet 100% of the reference nutrient intake (RNI) for three of 19 (16%) of the nutrients studied, whereas AF provided in excess of 250% of the RNI for six of 19 (32%) of the nutrients. During the trial, the nutrients on the OCF were two of 19 (11%) <100% and four of 19 (21%) >250% of the RNI. Only seven of 10 (70%) children on a PF met at least 100% of the UK RNI for calcium, compared to 17 of 19 (89%) on the OCF.
Conclusions:  It is important to offer older children an enteral feed that provides an optimal level of nutrients to meet their nutritional requirements. Feeds designed for 7–12-year-old children more closely meet nutrient requirements than paediatric or adult formulae, but require further modification to fully meet the nutritional needs of this group.     

Microbial contamination of enteral feeding formulas and diarrhea

Twenty-five medical and surgical patients receiving liquid ready-to-use sterile enteral formulas were evaluated prospectively to investigate the relation of diarrhea to serum albumin level, total lymphocyte count, delayed hypersensitivity to purified protein derivative, antibiotic therapy, administration rate and site of enteral formula, and microbial contamination of enteral feeds. Formulas were administered to 6 patients with hang times of up to 6 h by pump-assisted continuous drip and to 19 patients with hang times of up to 3 h as a bolus feeding. Samples of formulas for microbial culture were obtained aseptically before and after feeding on the first and eighth day of the study period. The incidence of microbial contamination of the formula before and after feeding was 1 of 49 samples (2.0%) and 10 of 48 samples (20.8%), respectively. There were 2 patients with diarrhea, which occurred on the second day. Formula samples from 2 patients (100%) with diarrhea and 2 samples from 23 patients (8.7%) without diarrhea were contaminated with 10(4) cfu/mL or more, respectively. A significant difference (P = 0.04) was detected between the two groups. The other factors studied showed no significant association with the incidence of diarrhea. In conclusion, contaminated formula appears to play a significant role in the etiology of diarrhea in patients receiving enteral feeding.     

The effect of poor handling procedures on enteral feeding systems in Hong Kong.

Two enteral feeding systems commonly used in Hong Kong were evaluated for ease of bacterial entry during assembly and delivery of feeds. Wearing new, non-sterile disposable latex gloves during the assembly of the systems did not contaminate the feeds. The risk of contamination increased for systems assembled with bare hands. Systems assembled with hands experimentally contaminated with bacteria resulted in definite contamination of feeds.     

Bacterial contamination of enteral feeding systems due to faulty handling procedures—a comparison of a new system with two established systems

Background: The purpose of this study was to compare the risks of introducing microbial contamination when assembling and running two commonly used, ready-to-hang, enteral feeding systems (Nutrison glass bottles and Steriflo) with a newly introduced system (Nutrison pack). Methods: The nutrient container tops of all systems were deliberately touched during assembly by a researcher wearing gloves contaminated with Klebsiella aerogenes. After touching, half the containers were immediately connected to giving sets, the other half were disinfected using alcohol wipes before connection to the giving sets. Systems were run for 24 h, with a change of nutrient container at 12 h for the Steriflo (2×1000 ml), Nutrison pack (2×1000 ml) and Nutrison glass bottles (2×500 ml), and at 6 h for the Nutrison glass bottles (4×500 ml). Feed samples for microbiological analysis were taken from feed in the systems at the 0 h assembly, and from residual feed in all discarded nutrient containers. Each protocol was repeated five times. Results: The percentage of feed samples in which K. aerogenes was detected reduced significantly from 68% for non-disinfected Nutrison glass bottles changed every 6 h, to 59% after disinfection, and from 51% to 0% after disinfection of Steriflo systems (Mann–Whitney, P< 0.05). For Nutrison glass bottles changed every 12 h the fall from 51% with no disinfection to 49% after disinfection was not significant (Mann–Whitney, P< 0.05). Nutrison packs were not disinfected and yet K. aerogenes was only detected in 2% of feed samples. This rate of contamination was significantly less than that for all the other non-disinfected systems (Mann–Whitney, P< 0.05). Conclusion: The results show a reduction in the incidence of bacterial contamination of the feed samples when systems were disinfected subsequent to being exposed to faulty handling procedures, thus supporting manufacturers recommendations to disinfect systems during assembly. The results particularly highlight the important role played by system design in reducing the levels and incidence of bacterial contamination of enteral tube feeds.