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Synopsis: An outbreak of bacteremia due to Serratia liquefaciens in a dialysis center proved to be due to contamination that occurred during pooling of the residual contents of single-dose vials of preservative-free epoetin alfa.
Source: Grohskopf LA, et al. Serratia liquefaciens bloodstream infections from contamination of epoetin alfa at a hemodialysis center. N Engl J Med 2001; 344:1,491-1,497.
Abstract: Ten episodes of Serratia liquefaciens bacteremia and six pyrogenic reactions occurred during a six-week period among patients in a Colorado dialysis center. The state health department invited the Centers for Disease Control and Prevention to conduct an investigation. In a cohort study, CDC investigators found that two risk factors were independently associated with infection or pyrogenic reaction. These were receipt of median doses of epoetin alfa greater than 4000 U and dialysis during an afternoon or evening session. The epoetin alfa was supplied in single-use, preservative-free vials of 10,000 U. Because there was typically substantial excess medication remaining in the vial after use, the staff routinely entered each vial with a needle for multiple doses, and then withdrew and pooled the residual when the vial was nearly empty.
Cultures of the center’s water supply did not yield S. liquefaciens, and cases occurred after reprocessing of dialyzers was discontinued. S. liquefaciens was isolated from 61 of 97 empty vials of epoetin alfa, as well as from a soap dispenser and a hand-lotion dispenser in the medication room where the epoetin alfa vials were stored. Blood, medication vials, hand lotion, and soap isolates of S. liquefaciens were identical by pulsed field gel electrophoresis. The outbreak stopped after the practice of re-entering single-dose vials and pooling of epoetin alfa was discontinued.
Commentary by Robert Muder, MD, hospital epidemiologist at the Pittsburgh VA Medical Center.
A cluster of bloodstream infections due to certain genera of Gram-negative bacilli, most notably Klebsiella, Enterobacter, or Serratia, should immediately suggest the possibility of a contaminated intravenous fluid or medication, particularly if the patients affected have no obvious primary source of infection.1,2 Bacteria of these genera can multiply rapidly in a variety of medications and IV fluid preparations once introduced.
The outbreak of S. liquefaciens bloodstream infections in this hemodialysis center was caused by the practice of re-entering preservative-free single vials of epoetin alfa multiple times, and pooling residual medication. The likely source of the organism was the hand care products in the medication room.
Grohskopf and colleagues noted that the staff typically "topped off" the soap or lotion in the dispensers when they were nearly empty, rather than cleaning and refilling them. This practice would tend to encourage multiplication of any contaminating organism to fairly high levels. Once the hands of the staff were contaminated, the vial stoppers could easily become contaminated during handling. The stoppers were cleaned with an alcohol swab prior to each entry; this is not a reliable sterilization method. Once introduced into the vial, the organisms were able to multiply during subsequent storage in the refrigerator.
The impetus for the multiple usage of vials and pooling of the epotein alfa was cost saving. Epoetin alfa, given to dialysis patients to increase red blood cell mass, is a moderately expensive medication ($10/1000 U, according to Grohskopf et al). The formulation used at this center was supplied in single-dose, preservative-free vials containing 10,000 U.
As the average dose given was about 4,000-6,000 U, there would have been a considerable amount of medication remaining in each vial that would otherwise need to be discarded. A survey of dialysis centers found that 58 of 71 (69%) used a single-dose preparation of epoetin alfa, and that 45 of 58 (78%) used the vials repeatedly; nine (16%) routinely pooled residual medication.
The lesson to be learned here is obvious. Disregarding good infection control technique as a cost-saving measure is hazardous. Further-more, it is likely to be counterproductive in the long run, since health care-related infec-tions (bacteremia in particular) are expensive to treat. It is disconcerting that this lesson must be relearned repeatedly.
1. Maki DG, et al. Nationwide epidemic of septicemia caused by contaminated intravenous products: Epidemi-ologic and clinical features. Am J Med 1976; 60:471-485.
2. Goetz AM, et al. An outbreak of infusion-related Klebsiella pneumoniae bacteremia in a liver transplantation unit. Clin Infect Dis 1996; 21:1,501-1,503. n