Background: Environmental and financial concerns have led to reuse of single-use medical devices and in particular, metered dose inhalers (MDIs). We are unaware of any published large-scale studies to assess this procedure's safety.
Methods: We cultured the MDIs of 254 patients used on the general medical and surgical services using broth immersion of the MDI in 128 cases and swab of the MDI in 126 cases. Metered dose inhalers were then disinfected with 70% isopropyl alcohol using spraying in 127 cases and by 2-minute immersion in 127 cases. All devices were then recultured using colony determination by liquid broth method, resulting in 4 groups: broth and immerse (71); broth and spray (57); swab and immerse (56), and swab and spray (70).
Results: A mean of 24 colonies of all organisms were cultured using the broth immersion technique and 0.94 using the swab technique (P = 0.001). Disinfection by immersion resulted in a mean of 1.46 colonies (all organisms) cultured versus 6.8 colonies by spray (P = 0.008). However, the rate of pathogenic bacterial culture was only 8 (3.1%) of 254 before disinfection and 1 (0.39%) of 254 after disinfection. The latter occurred with spray disinfection and consisted of 2 colonies of Enterobacteriaceae. Comparison of the aforementioned 4 groups revealed no significant differences save for broth and immerse versus broth and spray (P = 0.036) for all organisms irrespective of pathogenicity.
Conclusion: Metered dose inhalers can be safely reused in a general service setting after disinfection with either 70% isopropyl alcohol spray or immersion in isopropyl alcohol for 2 minutes.