Assessment of microbial growth in intravenous immune globulin preparations

The ability of intravenous immune globulin (IVIG) products to support bacterial and yeast growth was studied. Microtiter plates containing preparations of eight commercially available IVIG products were inoculated with 10(5) colony-forming units (CFUs) of bacteria per milliliter or 10(3) CFUs of yeast cells per milliliter. The organisms used were Candida albicans, Torulopsis glabrata, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Klebsiella pneumoniae. The plates were incubated at 3, 25, or 37 degrees C for seven days. For each organism and each temperature, a total of 16 identical wells were studied per preparation. Optical density was measured at 24-hour intervals to determine bacterial growth; yeast growth was determined visually. None of the IVIG preparations supported bacterial growth at any temperature over the seven-day period. No preparation supported visible yeast growth at 3 degrees C; however, most of the preparations did support yeast growth at 25 and 37 degrees C. The failure of the IVIG preparations to support bacterial growth at all temperatures and yeast growth at 3 degrees C suggests that a reconsideration of recommended expiration dates for IVIG products may be warranted.