Risk of cross-patient infection with clinical use of a needleless injectordevice

Background: Needleless injection devices use multiple-dose vials for the ad ministration of local anesthetics to patients. There is a theoretic risk of iatrogenic infection associated with use of these devices. Methods: This study used in vitro models to investigate the potential for t ransferring microbial pathogens among patients by using the Syrijet (Keysto ne Industries, Inc, Cherry Hill, NJ). Staphylococcus aureus and coagulase-n egative staphylococci were used to determine whether patient skin flora cou ld contaminate the instrument internal canal by postejection reverse flow a nd whether the staphylococci could survive on die ejection surface, in the internal canal, or in the anesthetic vial. Results: The ejection surface was contaminated by firing the device while i t was in contact with a contaminated surface. Postejection reverse flow dre w contaminants into the device, and increased with ejection volume. Reverse flow did not reach the multidose vial, and staphylococci did not grow in t he commercial anesthetic solution typically administered with the device. S urface, but not internal, contamination could be removed by swabbing with d isinfectant. Conclusion: Although autoclaving is the only way to ensure sterilization of this device, frequent cleaning of the ejection surface during clinical use minimizes the risk of cross-patient bacterial transfer.