Bacterial Contamination of Multi-Use Fluid Bags

By Anthony P. Carr, Dr. Med. Vet., DACVIM

Bacterial infections should concern any veterinarian, particularly if they are caused iatrogenically. Recent studies, briefly described below, found only minor levels of contaminations in reused intravenous fluid bags but more on ports after several days.

Intravenous fluid bag colonization

Although we all know it’s a less-than-ideal practice, many of us still keep a bag of fluids that we periodically reuse. In some cases these bags are used for subcutaneous fluid therapy in multiple patients or in the same patient (a relatively common practice in cats with chronic kidney disease for which the owners administer the fluids at home).

Of course, when the bag is punctured to obtain fluids, there’s always the risk of bacterial contamination. Indeed, studies show that contamination can occur in veterinary multiuse medication vials. One study found that 18% of multidose vials at a veterinary teaching hospital were contaminated with bacteria, in some cases with organisms that clearly were pathogenic.1 This study also cultured saline bottles and found that over a third contained bacteria.

Researchers from the Ohio State University looked for bacterial contamination of fluid bags in a veterinary emergency room (ER) and intensive care unit (ICU). The researchers used 1-L bags of saline (n=90) punctured three times daily. Samples were cultured on days 0, 2, 4, 7 and 10.2 The bags in the ER showed no bacterial growth on days 0 or 2. On day 4, 1.1 percent of the bags had positive test results for bacteria, and on days 7 and 10, 4.4 percent had positive results. None of the bags in the ICU were positive at any time point.

The injection ports were also sampled with a swab, and the following bacterial growth was found:

Day 0 – 4.4 %,   day 2 – 12.2% , day 4 – 17.8 % and days 7 and 10, 31.1 %.  Most contaminated ports were from the ER.

The results of this study, which were presented at the 2013 International Veterinary Emergency and Critical Care Symposium, suggest that bacterial contamination of fluid bags used over a longer period is rare but does occur. If the bag is used for only two days, the risk of contamination appears to be low. Infection of fluid bags may be linked to the severity of port contamination.

A previous study showed that if an alcohol swab was used before inserting a needle into a port, the introduction of bacteria into the vial was significantly reduced.1 This study also demonstrated a much higher prevalence of bacterial contamination in bottles of saline solution.

The differences in the results of these two studies may be related to environmental differences in which the bags were used. It’s possible that the ER or ICU staff paid close attention to hand hygiene and suitable practices when taking fluids from a bag, something that may not occur in a less-intense practice environment.

The takeaway: Although not an ideal practice, multiple uses of intravenous fluid bags is feasible, although attention should be paid to appropriate port disinfection before removal of fluids, and the bag should be discarded after two days.


1.  Sabino CV, Weese JS.  Contamination of multiple-dose vials in a veterinary hospital.  Can Vet J.  2006:  47 (8) 779-782.

2.  Guilaumin J, Olp N Magnassun K et al.  Influence of hangtime on bacterial colonisation on intravenous bags in a veterinary emergency and critical care setting.  (Abs)  J Vet Emerg. Crit. Care.  2013.  23: S6

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