Risks of allergy vial contamination: Comparison of mixing in-office versus under ventilation hood

Objective: Compare the risk of bacterial contamination of allergy immunotherapy vials prepared in-office versus those mixed under a ventilation hood. Study Design: Prospective single-blinded study. Setting: Tertiary otolaryngology outpatient clinic. Results: Five hundred thirty-seven vials were prepared and cultured for aerobes and anaerobes over an 11-month period. Three hundred twenty vials were arbitrarily assigned to in-office preparation and 217 to under-hood preparation. A total of two positive cultures occurred in vials prepared in-office and one from under-hood preparation. Follow-up cultures of these three vials were all negative. No patients receiving injections had signs or symptoms of skin or systemic infections from the injections. Conclusion: Our results suggest that the risk of bacterial contamination in immunotherapy vials in both groups is rare.