Retrograde (ascending) bacterial contamination of enteral diet administration systems

Appropriate handling and storage reduce the risk of bacterial growth in enteral feeding systems reused within 24 hours

BACKGROUND

Enteral tube feeding can require considerable amounts of plastic equipment including delivery sets and containers, often disposed of after a single feeding session because of bacterial contamination concerns. The aim of this research was to assess whether reuse of delivery sets and containers for up to 24 h is safe from a microbiological perspective.

METHODS

Four enteral tube feeding systems (FS) were tested under hygienic controlled or repeated inoculation challenge conditions using key foodborne pathogens, to assess bacterial growth over time (FS1: ready-to-hang, closed 1-L system with delivery set reused, stored at room temperature [RT]; FS2: a prepared, powdered, open 1-L system with delivery set and container reused, stored at RT; FS3 and FS4: prepared, powdered, open 200-ml bolus systems with delivery set and container reused, stored at RT [FS3] and refrigeration [FS4]). Feed samples were cultured at 0.5, 6.5, 12.5, 18.5, and 24.5 h with >2 Δlog considered significant bacterial growth.

RESULTS

Under hygienic control, FS1, FS3, and FS4 were below the level of enumeration (<5 CFU/g) for all bacteria tested, at all time points. In FS2, significant bacterial growth was observed from 18.5 h. Under repeated bacterial inoculation challenge, no significant growth was observed in FS1 and FS4 over 24.5 h; however, significant growth was observed in FS2 after 6.5 h and in FS3 after 10-12 h.

CONCLUSION

With hygienic handling technique, there is limited bacterial growth with reuse of delivery sets and containers over 24 h. Refrigeration between feeding sessions and using boluses of reconstituted powdered feed reduce bacterial growth risk.

Optimal Frequency for Changing Single-Use Enteral Delivery Sets in Infants after Congenital Heart Surgery: A Randomized Controlled Trial

Objective We aimed to assess the optimal frequency for changing single-use enteral delivery sets during postoperative enteral feeding in infants with congenital heart disease (CHD).Methods We enrolled 120 CHD infants who were fed using an enteral nutrition pump directly connected to a milk bottle with a single-use enteral delivery set in a four-arm randomized controlled trial (ChiCTR2000039544). Patients were randomized into four groups based on the replacement frequency of the enteral delivery set (6 h, 12 h, 18 h, and 24 h groups). The primary outcome was the percentage of contaminated enteral delivery sets (overgrowth of microbiota and colonization of pathogenic bacteria). Secondary outcomes included evidence of infection, gastrointestinal tolerance, intestinal microflora dysbiosis, and healthcare costs.Results The percentages of microbial overgrowth detected in the 6 h, 12 h, 18 h, and 24 h groups were 6.7%, 30.0%, 46.7%, and 80%, respectively (P < 0.001). Significant differences were observed between the 6 h and 18 h groups (P < 0.001), the 6 h and 24 h groups (P < 0.001), and the 18 h and 24 h groups (P = 0.007). Meanwhile, pathogenic bacterial colonization was detected in 0, 4, 6, and 11 delivery sets in the 6 h, 12 h, 18 h, and 24 h groups, respectively (P = 0.002). No difference in clinical symptoms was found among the four groups. The total cost per patient in the 12 h group and the 18 h group was 340.2 RMB and 226.8 RMB, respectively.Conclusion Taking into consideration both microbial overgrowth and cost-effectiveness, the results of this study indicate that for children receiving continuous enteral feeding following CHD surgery, the optimal frequency for changing the single-use enteral delivery set when formula reconstituted from powder is used is 18 hours.

Revisiting the Evidence for the Reuse of Enteral Feeding Equipment in Ambulatory Patients: A Systematic Review

BACKGROUND

The reuse of enteral tube feeding (ETF) equipment is not recommended due to the risk of microbial contamination and subsequent risk of infection; however, this practice continues in many ambulatory settings. A systematic review of the literature was undertaken to review the evidence underpinning the cleaning and reuse of ETF equipment.

METHODS

Studies that investigated the reuse, decontamination, and/or cleaning of ETF equipment were considered for inclusion. Electronic databases were searched (no limits were placed on date of publication, age, or duration of reuse). Extracted data were assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) and reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations.

RESULTS

Ten studies met inclusion criteria: 3 investigated changes to clinical outcomes with extending reuse from 24 to ≤72 hours using water rinses; 5 considered the efficacy of various cleaning methods assessed in laboratory conditions; 2 used a combination of both approaches. Sufficient data to allow GRADE assessment was found only for bottle-type containers.

CONCLUSIONS

A very low level of evidence supports the cleaning and reuse of rigid and "unspecified" bottle containers; no studies were found to inform the reuse of syringes used for bolus feeding or any equipment used for water infusion or flushes. There is an absence of literature evaluating the safety and clinical outcomes of cleaning and reusing ETF equipment, and research is required to support equipment reuse.

A Microbiologic Study of Enteral Feeding Hang Time in a Burn Hospital: Can Feeding Costs be Reduced Without Compromising Patient Safety?

BACKGROUND

Procedural changes for hospitalized patients must always balance safety with fiscal constraints. Microbiologic contamination of enteral feeding solutions has been previously associated with nosocomial infections. Formula manipulation and hang time contribute to microbial load, and there is considerable variation in hang time recommendations in the medical literature. With cost containment in mind, the purpose of this performance improvement study was to determine if an increase in hang time of a modular tube feeding product would increase microbial load or affect the nosocomial infection rate in pediatric burn patients.

METHODS

This biphasic trial initially evaluated the microbial load of the feeding after delivery of two 4-hour aliquots into a container using the same delivery set (total hang time of 8 hours; number of tests = 20). Second, once this feeding procedure was deemed microbiologically safe, tube feedings were administered to patients, and both microbial load and nosocomial infection rate were monitored for 1 year.

RESULTS

Contamination levels at the end of the 8-hour period using the same feeding set with 2 consecutive 4-hour feeding aliquots (number of tests = 38) were lower than standard recommendations. The hospital's nosocomial infection rate was not altered by this procedural change, and feeding-set expenses were reduced.

CONCLUSIONS

The hang time of our enteral feeding administration set can be increased safely from 4 hours to 8 hours, with the tube feeding preparation added as two 4-hour aliquots without a significant change in microbial load or nosocomial infection rate, thus promoting simultaneous fiscal responsibility and patient safety.

Definitions, attitudes, and management practices in relation to diarrhea during enteral nutrition: a survey of patients, nurses, and dietitians

BACKGROUND

Diarrhea is a common complication in patients receiving enteral nutrition (EN), and understanding this problem among patients and healthcare professionals is required. The aim of the study was to investigate patients', nurses', and dietitians' definitions of diarrhea during EN, the attitudes of nurses and patients toward it, and the management practices of nurses and dietitians in response to diarrhea during EN.

METHODS

Twenty-two patients receiving EN, 57 nurses, and 33 dietitians were recruited and interviewed in a cross-sectional study, using a questionnaire that had been developed following an extensive literature review and pretested for clarity.

RESULTS

The ratings assigned by the 3 groups differed significantly for all the characteristics used to define diarrhea: frequency (P = .006), quantity (P < .001), consistency (P = .003), color (P < .001), odor (P < .001), and incontinence (P < .001). Patients gave incontinence the highest rank when defining diarrhea, whereas the healthcare professionals gave fecal consistency and frequency the highest ranks. Patients and nurses rated the unpleasantness of each characteristic of diarrhea during EN differently, with patients rating incontinence and fecal frequency and nurses rating odor and changing the patients' underwear as the most unpleasant characteristics. Nurses and dietitians differed in the frequency with which they adopted various strategies to manage patients who developed diarrhea during EN.

CONCLUSIONS

Patients have different definitions and attitudes toward diarrhea during EN from those of nurses and dietitians. Patients' perceptions need to be understood and respected by healthcare professionals to improve patient-centered care.

Role of enteral nutrition in the incidence of diarrhea among hospitalized adult patients

OBJECTIVE

This study examined the risk of diarrhea as a result of providing enteral nutrition in the hospital setting, adjusting for other clinical and therapeutic factors.

METHODS

Adults admitted to a general tertiary care university hospital, in clinical or surgical units, were enrolled in the study between June 2004 and May 2005 and prospectively followed during their hospital stay. For each patient treated with enteral nutrition (n = 302), a comparable non-treated patient from the same ward (who also received antibiotics previously) and was similarly cared for by the same hospital staff was included in the study (n = 302), constituting a double-cohort study. All patients were seen three times per week, on alternating days, until the occurrence of diarrhea or hospital discharge. Cox's regression analyses were applied for adjustments.

RESULTS

The incidence of diarrhea was 18% for patients receiving enteral nutrition and 6% for non-treated patients (P < 0.01). In multivariate analyses, enteral nutrition was independently associated with diarrhea (hazard ratio 2.7, 95% confidence interval 1.6-4.7), even adjusting for age (hazard ratio 1.02, 95% confidence interval 1.00-1.03) and hospitalization during the summer months (hazard ratio 2.4, 95% confidence interval 1.5-3.9). Patients for whom strict adherence to delivery-set washing-and-changing procedures was observed (on >75% of days) presented a lower incidence of diarrhea (6.5% versus 20.3%, P = 0.02; and 5.9% versus 19.8%, P = 0.05, respectively).

CONCLUSION

Providing enteral nutrition to the hospitalized elderly during the summer months is associated with a higher risk of diarrhea. Strategies aimed toward improvement in the quality of enteral nutrition practices should be evaluated to minimize this deleterious clinical outcome.

Enteral access options and management in the patient with intestinal failure

Intestinal failure refers to a condition in which inadequate digestion and/or absorption of nutrients leads to malnutrition and/or dehydration. Enteral access is occasionally used in patients with intestinal failure either for the purpose of providing nutrition or decompressing the gut. As a consequence, it is important that clinicians caring for these highly complex patients be knowledgeable in enteral access options and experienced in the subsequent care of these tubes. In this review, enteral access options and the potential complications associated with their use will be reviewed. Importantly, this information is relevant to both the pediatric and adult patient with intestinal failure.

Analysis of sites of bacterial contamination in an enteral feeding system

BACKGROUND

Contamination of enteral feedings is an often overlooked source for bacterial infection in the intensive care unit. A new 1-L enteral feeding system with minimal chances of touching critical areas (Nutrison Pack) was compared with routinely used 0.5-L glass bottle systems.

METHODS

Patients admitted to intensive care were randomized to Pack or glass bottle feeding systems. Cultures were taken from the delivery sets 5 times during the day and from feeding containers and different sites of the system after 24 hours.

RESULTS

Bacteria were present in 3 of 112 glass bottles and in 2 of 95 Pack bags. True bacterial contamination (defined as >10(2) colony-forming units/mL, with same bacteria also present in the delivery set) was found in none of the Packs with a 12-h (69 Packs) or a 24-h (26 Packs) hanging time and in only 1 of the glass bottles with a hanging time of 24 hours, which exceeded the advised hanging time of 8 hours. In contrast, the contamination rate of delivery sets was 48%, with increasing bacterial counts over the day and 4 subsequent days. Bacteria mainly belonged to the group of potentially pathogenic bacteria (Enterobacteriaceae and Pseudomonaceae). They likely originated from throat, lungs, and stomach and grew into and along feeding tubes upwards until they reached the delivery set.

CONCLUSIONS

Prolonged hanging times of Pack bags were safe with respect to bacterial contamination. However, the bacterial safety of enteral feedings is more likely to be endangered by the endogenous route of contamination rather than exogenous contamination, as high bacterial counts were found in feeding tubes and delivery sets as a result of retrograde growth.

Bacterial contamination of enteral nutrition in a paediatric hospital

A prospective study was performed in a paediatric hospital to evaluate the incidence of bacterial contamination in enteral nutrition bags and to determine the critical points of process. During two separate one-month periods, all children receiving pump-assisted enteral nutrition were enrolled in the study. Samples for microbiological analysis were collected from enteral nutrition bags after administration in the first and second study period (sample T(2)). In the second study period, two additional samples were made at the end of the feed preparation process. One was refrigerated immediately (sample T(0)) and the other was sealed in a tube that followed the enteral nutrition solution until the end of its administration (sample T(1)). Bacterial contamination was detectable above 10(2)cfu/mL. Twenty-six out of 40 patients were included in the first study period and 14 out of 44 in the second study period. Contamination (>10(2)cfu/mL) occurred in nine of 26 samples (35%) and seven of 14 samples (50%) in the first and second study periods, respectively. Of these, five (20%) and three (21%) contained significant contamination (>/=10(4)cfu/mL). Bacteria of low pathogenicity were found in T(0) samples. Bacteria present in T(2) samples were pathogenic and multiple in 50% of cases. These results suggest that manipulation of the enteral nutrition bags at the bedside is critical for bacterial safety.

A review of the nursing care of enteral feeding tubes in critically ill adults: part II

Enteral tubes are frequently used in critically ill patients for feeding and gastric decompression. Many of the nursing guidelines to facilitate the care of patients with enteral tubes have not been based on current research, but on ritual and opinion. Using a computerised literature search and an evidence-based classification system as described by the Joanna Briggs Institute for Evidence Based Nursing and Midwifery (JBI), a comprehensive review was undertaken of enteral tube management. Several nursing practices related to enteral tube management are described. Evidence to support alternate methods of tube placement assessment other than abdominal X-ray was inconclusive. Enteral feeding should continue if gastric residual volumes are not considered excessive, as feeding is often withheld unnecessarily. Frequency of checking gastric residual volumes is largely opinion based and varies considerably, but prokinetics that aid gastric emptying should be used if absorption of feeds is problematic. Other recommendations include continuous rather than intermittent feeding, semi-recumbent positioning to reduce the risk of airway aspiration and diligent artificial airway cuff management. Contamination of feeds can be minimised by minimal, meticulous handling and the use of closed rather than open systems. Generally, there was little high quality evidence to support practice recommendations leaving significant scope for further research by nurses in the management of patients with enteral tubes.

Is a 24-h cyclic closed enteral feeding system microbiologically safe in geriatric patients?

BACKGROUND AND AIMS

The microbiological quality of a 1-l closed enteral feeding system (CS) was prospectively monitored under clinical conditions simulating cyclic feeding over a 24-h period in geriatric patients.

METHOD

The set was connected after diet sampling (T0). After 5-h feeding, the set was disconnected and a sample taken (T5). Diet was sampled after 12 h before (T12A) and after a 10 ml diet-flush of the set (T12B), after 24-h (T24) and in the pouch (P24). Concentrations of micro-organisms were considered significant when above 10(4) colony-forming units per millilitre.

RESULTS

Twenty-one CS were examined. T0 samples were all sterile; 10 out of 21 T5 were contaminated. The microbiological content of the diet was lower in T12B, compared to T12A (P=0.002). None of the P24 samples was contaminated; 19 were sterile and two contained low levels of micro-organisms that had been previously found in the sets.

CONCLUSION

The CS was sterile before connecting to the patient. Retrograde contamination of the set was observed without contamination of the pouch after 24-h hanging time. Performing a diet-flush decreased the rate of diet contamination at the distal extremity of the set. Thus, cyclic enteral nutrition using the same pouch during a 24-h period seems to be safe in geriatric patients.

Enteral feeding. Nasogastric, nasojejunal, percutaneous endoscopic gastrostomy, or jejunostomy: its indications and limitations

The following article is intended to provide a review of the current state of enteral feeding; a rapidly changing and developing field. It covers the type of feed, the routes of access, and the problems that can occur with enteral feeding.

Contamination of gastrostomy feeding systems in children in a home-based enteral nutrition program

BACKGROUND

There are few data concerning the risk of contamination of enteral feeding systems via gastrostomy in children, and none for conditions that pertain to home-based care.

METHODS

To investigate the risk of contamination of enteral feeding systems during the home-based care of 20 children receiving gastrostomy tube feeding, five samples were taken for analysis: two samples before the enteral feeding period (gastrostomy, enteral feeding system) and three after this period (gastrostomy, distal giving set, liquid remained in container). Microorganisms were identified and counted. Different factors were studied to elucidate their role in bacterial colonization: acid suppressive therapy, gastrostomy tube or button, hanging feeding time, rate of enteral feeding, gastric pullulation and retrograde contamination, manipulation error, and use of open or closed enteral feeding systems.

RESULTS

Overgrowth was defined as a microorganismal load exceeding 10(4) colony-forming units (cfu)/mL. Overgrowth was present in 85% of gastrostomy samples before enteral nutrition started. Most microorganisms belonged to gastric flora. Some bacteria had an environmental origin or derived from cutaneous flora. Forty-five percent of the lines showed overgrowth at the end of enteral nutrition period, mainly with the same microorganism found in the gastrostomy. Closed enteral bags remained sterile, even if manipulation error occurred. Duration, rate of enteral feeding, and acid suppression treatment were not risk factors for overgrowth.

CONCLUSIONS

Retrograde contamination of gastrostomy feeding systems occurs frequently. The preferential use of closed enteral feeding systems is recommended for home-based enteral nutrition programs.

Comparison of microbial contamination of enteral feeding solution between repeated use of administration sets after washing with water and after washing followed by disinfection

We compared microbial contamination of in-use enteral feeding solution from repeatedly used administration sets (a delivery bag and an infusion tube) after washing with water or washing followed by disinfection. In eight hospitals where administration sets were re-used after washing with water, residual solution was collected from both the delivery bag and the distal end of the infusion tube immediately after use and the microbial contamination level and microbial species found examined. The residual enteral feeding solution (28 samples) in the delivery bag grew 10(2)-10(8) colony forming units (cfu)/mL and 36 samples from the distal end of the infusion tube grew 10(2)-10(9) cfu/mL. Re-processing was changed to washing with water followed by disinfection with 0.1% (100 ppm) sodium hypochlorite, and similar examinations were performed. The residual solutions in the bag (22 samples) and in the distal end of the infusion tube (24 samples) were contaminated with < 10(1)-10(4) cfu/mL each, a significant decrease (P < 0.01, Wilcoxon U-test) compared with washing with water alone.

The effect of system design on bacterial contamination of enteral tube feeds

The effect of recent changes in system design on the levels and incidence of bacterial contamination in enteral tube feeds was examined by comparing two different systems. Adult patients who had been identified as requiring enteral tube feeding were allocated to receive sterile, whole protein enteral feed from either 2 x 1000 mL triple foil laminated pouches (Nutrison Standard, Nutrison Pack, Nutricia Ltd, UK) attached to a Flocare 800 pack giving set or from 2 x 1000 mL rigid plastic bottles (Osmolite, Ross Ready-to-Hang, Abbott Laboratories, UK) connected to a Patrol Pump set. Samples of feed from the nutrient containers were sent for microbiological analysis each time the container was changed (12 and 24 h) and samples from the distal ends of giving sets after 24 h.Bacterial contamination was found in a significantly lower number of Nutrison Packs (14/120; 12%) as compared with Ross Ready-to-Hang containers (25/120; 21%) (Fisher's exact test, 1 tailed test, P > or = 0.05). However, both the level and frequency of contamination of the feed samples collected from the distal ends of the giving sets of both types of system were similar to each other but higher than those from the nutrient containers (57/120 contaminated giving sets as compared with 39/240 nutrient containers; P > or = 0.00001). On 32/120 patient days only the giving set samples were contaminated. The results highlight the important role that improvements in system design, such as the use of recessed spikes on giving sets have in reducing the risk of bacterial contamination of enteral tube feeds introduced due to faulty handling procedures, and further implicate retrograde spread of the patients' own flora as a source of contamination in the giving set.

Effect of high ambient temperature on contamination and physical stability of one-liter ready-to-hang enteral delivery systems

The effect of high ambient temperature on the physical stability and bacterial contamination of 1-L, prefilled, closed enteral feeding systems was examined under simulated clinical conditions. One hundred Jevity Ready-to-Hang enteral feeding systems (Abbott Park, IL, USA) were placed in a 37 degrees C incubator for 24 h. The Ready-to-Hang formula containers were visually inspected at 0 and 24 h. Formula samples were collected from the containers at 24 h and plated on trypticase soy agar. Two samples had insignificant bacterial growth of one colony-forming unit per milliliter that was not demonstrated in repeat culture. No growth was observed for any other sample. Additional samples collected from the two apparently contaminated delivery sets showed no growth. No set showed signs of formula instability, such as coagulation, clumping, or curdling. These findings suggest that, even at a high ambient temperature of 37 degrees C, the risk of bacterial contamination or compromised physical integrity is very low with the use of 1-L, prefilled, closed enteral feeding systems.

Bacterial contamination of ready-to-use 1-L feeding bottles and administration sets in severely compromised intensive care patients

OBJECTIVE

In intensive care patients, enteral feeding requires sterile feedings because of infectious complications and adequate supplements to meet nutritional needs. Heretofore, prepacked, large-volume formula containers were developed, but bacterial contamination occurred in 4% to 15%. Our objective was to investigate the microbial contamination rate of 1-L feeding bottles and newly designed administration sets over hanging times of 24 hrs in the intensive care unit (ICU).

DESIGN AND SETTING

A prospective observational cohort study of patients admitted to the ICU of a university hospital.

PATIENTS

All consecutive patients fed via a nasojejunal tube for at least 4 days.

MEASUREMENTS

Cultures of feeding bottles, administration sets, and gastric and tracheobronchial aspirates at day 0, 1, 2, 4, and 7.

RESULTS

A total of 4% of feeding bottles and 74% of infusion sets contained >10(2) colony forming units (CFU)/mL. Gastric and bronchial aspirates were positive in 90% and 92%, respectively. Bacterial counts of feeding bottles were 10(2)-10(5) CFU/mL, and the main bacteria isolated included Enterobacter cloacae, Klebsiella oxytoca, and enterococci. One third of all cultured bacteria in feeding bottles, administration sets, stomach, and lungs belonged to the Enterobacteriaceae family, which was held responsible for the nosocomial infections in the ICU. None of the 1-L feeding bottles with a hanging time of 19-24 hrs was contaminated. Only bottles that had to be exchanged because of need for a faster rate of infusion proved to be contaminated, apparently without clinical consequences. With time and the increasing severity of disease, the administration sets became contaminated at an increasingly faster rate and with higher bacterial counts mainly through retrograde growth of endogenous bacteria. The final step of bottle contamination might have been the bacterial transfer by nurses' hands.

CONCLUSION

Despite an almost ideal design of the enteral nutrition delivery system, a 4% contamination rate of initially sterile feedings with clinically relevant bacteria and the fact that only manipulated systems showed bacterial growth are of concern.

Catch-up growth in children treated with home enteral nutrition

OBJECTIVE

This study was designed to determine the effect of home enteral nutrition on the outcomes of growth and the relationship between growth and entrance anthropometric criteria.

METHODS

We reviewed the medical records of 78 consecutive children (median age, 20 months) who were enrolled in the home enteral feeding program at the Alberta Children's Hospital (Calgary, Alberta, Canada) between 1993 and 1995. Weights, heights, and weight-for-heights were expressed as Z scores, using the Centers for Disease Control and Prevention anthropometric growth curve software. To evaluate growth outcome, the total group was further subdivided using anthropometric criteria into appropriate, wasted, or stunted at the time of entry to the program. In a subgroup of 36 children on whom anthropometric data was available for a median length of 5.7 months, Z scores were compared at 3 points in time: before entry, at time of entry, and last follow-up.

RESULTS

Patients were classified into five main groups: 11 (14%) had pulmonary disease, 26 (33%) had a gastrointestinal disorder, 21 (27%) had congenital defects, 10 (13%) had a neurologic disorder, and the remaining 10 (13%) had a variety of other illnesses, including malignancies and metabolic disorders. Patients were on the program for a median duration of 8.9 months. It was found that during the period of support within the program, enteral feeding was successful in improving weight-for-age Z scores by 0.42 standard deviations but the effect on height-for-age Z scores and weight-for-height Z scores did not reach significance for this population. The subgroup of 36 children on whom longitudinal anthropometric data was available before entering the program was found to have had a significant drop in weight Z scores between the time before program entry (median length of time, 5.7 months) and the time of program entry, which indicates that these children were falling off the growth curve before commencing enteral feeding. To evaluate growth outcome, the total group was further subdivided using anthropometric criteria into appropriate, wasted, or stunted at the time of entry to the program. In the group of appropriate growth patients, while in the program, 50% had catch-up growth for weight (positive change in Z scores) and 33% for height. In the wasted patients, 92% improved their weight percentile and 75% their height percentile. In the stunted group, 71% had catch-up growth for weight and 74% for height.

CONCLUSION

We concluded that the enteral feeding program was able to promote catch-up growth or maintain growth along percentiles in the majority of children.

Clinical and laboratory evaluation of a closed enteral feeding system under cyclic feeding conditions: a microbial and cost evaluation

Cyclic feeding schedules are now commonly used in conjunction with closed enteral feeding systems. Some manufacturers and clinicians have speculated that closed system cyclic feeding may promote formula contamination via retrograde movement of bacteria during the "no-flow" periods. Using both laboratory and clinical settings, our study evaluated whether retrograde bacterial movement under "no-flow" conditions results in contamination of closed system feeding containers. The clinical phase was conducted with 57 closed system feeding containers used to feed nursing home residents. In both laboratory and clinical testing there was no evidence of container contamination at 36-48 h, nor was there evidence of retrograde movement of bacteria beyond the drip chamber. Formula waste and costs were also analyzed using several 24- or 36-h hang time scenarios. Provided the appropriate container size is used, potential cost savings between $67 to $135 per patient per month may be achieved with the 36-h hang time scenarios. Retrograde movement of bacteria does not appear to be a source of closed system feeding container contamination in systems that incorporate a drip chamber. Using the appropriate size feeding container and systems with at least a 36-h hang time will result in significant cost savings.

The effects of rinsing enteral delivery sets on formula contamination

This study investigated whether rinsing enteral delivery sets before formula addition affects formula contamination. Both a simulated and a clinical phase were conducted. In the simulated phase, Osmolite (Ross Laboratories, Columbus, OH) was infused continuously through 52 delivery sets into a flask via enteral infusion pumps for 24 hours. The delivery sets were randomly assigned to two groups of equal size. One group was rinsed with tap water before new formula was added at 8 and 16 hours, and the other group was not rinsed. At 8, 16, and 24 hours, samples of formula were collected from the delivery sets, and bacteria counts were obtained. In the clinical phase, 23 critically ill patients receiving Osmolite continuously were randomly assigned to a rinse or no-rinse group. The same formula addition and rinse protocol from phase I was used. Formula samples were obtained at 24 hours. In both phases, there were no significant differences between the rinse and no-rinse groups with respect to bacteria counts at any time period. The findings suggest that rinsing may be unnecessary if delivery sets are used continuously for 24 hours or less; however, the possibility of a type II error because of the small sample size of this study must be recognized.

The Sir David Cuthbertson Medal Lecture. Enteral-feeding-related diarrhoea: proposed causes and possible solutions

So to summarize the key points: 1. concomitant antibiotic therapy, infected diets and possibly hypoalbuminaemia can lead to enteral-feeding-related diarrhoea; 2. the small intestinal responses to both intragastric and intraduodenal enteral feeding are normal and predictable; 3. there is an ascending colonic secretion during enteral feeding which is more profound during intragastric feeding; 4. the suppression of distal colonic motor activity occurs only during high-load feeding and is probably a secondary phenomenon to the hormonal and secretory responses; 5. peptide YY appears to be intrinsically bound up with the causation of the secretory effect; 6. the secretory effect is abolished by intracaecal SCFA.

Assessment of the microbiological safety of enteral feeds when used with a prolonged feeding time

The microbiological risks of using a ready-to-use 1-litre enteral feeding system (Nutrison Steriflo) in a centre for burn patients were assessed. Such a system will have a relatively long hanging time (> 8 h). This could possibly lead to increased microbiological risks, because if the feed has been contaminated during use, microbes have a longer time available to multiply to high numbers. Multiplication will be relatively rapid due to the temperature conditions in the ward. A study was therefore carried out in which the microbiological quality of enteral formulae remaining in the bottle and giving set at the end of feeding burn patients (n = 5) was determined. From the 80 samples harvested from bottles and giving sets, microbiological analyses at all sampling points were performed in 54. It was shown that the microbiological quality of formulae in bottle and giving set remained good (colony count < 1 per ml), apart from in three exceptional cases. Fifty-one samples remained sterile throughout the feeding period. The results clearly show that the well-developed design of the system, combined with adherence to hygienic procedures by the nursing staff, make it possible to feed burn patients in a microbiologically safe way, even when a relatively long hanging time is used.

Review: microbiology of the gastrostomy tube

This review summarizes what is presently known about microbial colonization of silicone gastrostomy feeding tubes and their deterioration. Feeding tubes are frequently colonized by fungal and bacterial organisms. Candida organisms seem to originate from the oral cavity from where they colonize the stomach and the gastrostomy tubes. It appears that many microorganisms are able to metabolize certain polymer additives, and although this is well described for polyvinyl chloride, it is not for silicone elastomers. However, clinical evidence for a role of microorganisms in the deterioration of silicone feeding tubes is very strong. The clinical significance of gastrointestinal tract seeding from gastrostomy tubes, which act as incubators, is not fully understood and deserves further study. Likewise, deterioration of feeding tubes must be investigated systematically to address the safety and economical issues it presents.

Oral Candida colonizes the stomach and gastrostomy feeding tubes

The lumen of gastrostomy tubes is frequently colonized with Candida. To investigate the source of this contamination, 20 consecutive malnourished patients undergoing placement of a percutaneous endoscopic gastrostomy tube and ten ambulatory controls having routine upper endoscopy performed had both their oral cavity and gastric antrum swabbed and cultured. Percutaneous endoscopic gastrostomy tube recipients who after several weeks were still under our care (9 of 20) had the lumen of their tubes cultured. Fungi were isolated from the stomach in 13 (65%) of 20 patients undergoing percutaneous endoscopic gastrostomy tube placement but in only 1 of 10 ambulatory patients (p < .01). The species isolated from the oral cavity, the stomach, and later the gastrostomy tube were identical in most cases. We conclude that gastrostomy tubes are probably colonized by oral organisms that have made their way into the stomach.