Enteral formula study finds high contamination

Hand washing, proper preparation key factors

Enteral formula (EF) — particularly powdered products that may be contaminated by health care workers during mixing — may grow subsequent high colonization counts of bacteria, reports Donna Ottoviani, RN, MSN, nurse coordinator for the nutritional support service at the University of Pittsburgh Medical Center.

In a study presented recently in Washington, DC, at an educational conference of the American Society for Parenteral and Enteral Nutrition, Ottoviani reported that health care workers preparing enteral fluid were the most likely source of the contaminations. She recommended education and reinforcement of both proper hand-washing technique and the appropriate preparation and administration of EF. Another possible contributing factor was the medical center’s practice of mixing EF products on individual nursing units rather than at a central location where aseptic preparation can be more easily controlled, she says. Because EF administration is not considered as aseptically critical as intravenous administration, for example, it may fall by the wayside in terms of infection control, she says. Likewise, adverse outcomes in patents receiving EF are not easily linked to the formula, she adds.

’It’s very hard to correlate contamination of EF with diarrhea unless you had a huge study group,” she says. ’I still believe in this day and age, when as many patients are immunocompromised, I don’t think that this degree of bacteria is safe. It’s very hard to prove cause and effect, but it is an area we need to at least pay attention to.”

In the study, 103 patients receiving continuous EF for at least three days were followed for 24 hours. At the end of a 24-hour EF hang-time, the administration set and container were transported to the laboratory for quantitative bacteriological culture. High level bacterial contamination of the EF was defined as levels of colony forming units of 103 or greater. High level contamination was found in 27 (26%) of the samples cultured, she reports.

’This was surprising considering we took [samples] from very high up in the line — actually from the container itself,” Ottoviani says. ’So the [possibility] of retro migration back up the tube is very slim in our estimation. I don’t think it is coming from the patients themselves.”

It was unclear whether contaminated enteral formula led to any nosocomial infections, but three of approximately 17 patients for which blood cultures were also available tested positive for the identical organism contaminating the fluid. Bacteria included Bacillus species (26%), Enterococcus faecalis (15%), Klebsiella pneumoniae (15%), coagulase-negative Staphylococcus (6%), Citrobacter freundii (6%), Pseudomonas aeruginosa (6%), and Enterobacter cloacae (6%).