Sterility of refrigerated injectable collagen syringes after injection of patient

Background: Injectable collagen has been used for more than 15 years to correct soft tissue cosmetic defects. After injection, the collagen remaining in the syringe is often refrigerated for later use in the same patient, despite manufacturer and Food and Drug Administration recommendations to discard the unused collagen. Objective: This study examined the incidence of bacterial contamination of stored collagen. Methods: Syringe needle tips and collagen from 50 previously used syringes containing either Zyderm I, Zyderm II, or Zyplast were cultured separately under aerobic and anaerobic conditions. Bacterial isolates were identified. Results:Propionibacterium acnes was cultured from 7 of 50 needle tips. One positive needle tip culture grew both P. acnes and Staphylococcus aureus. Bacteria were isolated from only one collagen sample that grew a nonhemolytic streptococcus that may have represented a laboratory contaminant. Conclusion: Syringes of collagen stored for repeated use rarely become contaminated with bacteria despite frequent contamination of their needle tips. Skin abscesses after collagen injection should be cultured under anaerobic, as well as aerobic, conditions so that infections caused by P. acnes will not be missed.