Surface monitoring in isolators: feedback on a national survey of practices

Introduction
Currently, our surfaces samplings are carried out using dry swabs impregnated with sterile diluent. Agar inoculation and incubation are subcontracted to the biology laboratory (BL). Following non-compliances, we wish to upgrade our practices. The aim of this study is to benchmark current surfaces monitoring practices in isolators.

Materials and Methods
Based on cleanrooms requirements and researching surface sampling available on the market, we have designed a form with 5 items: contact plates, contact slides, Petrifilm® tests, swabs and gloves prints. For each item, type of surface, sampling method, media and LB subcontracting are discussed. For gloves prints, type of glove, production time and frequency are requested.

Results
Out of 48 pharmacotechnical units consulted, 27 answered (56%): 13 (48%) use a combination of contact plates and swabs, 9 (33%) only contact plates and 5 (19%) only swabs; no one uses contact slides or Petrifilm^® tests.
18 (82%) units use contact plates for all flat surfaces and 4 (18%) only for work plan; 17 units (77%) perform manual pressure sampling. 21 units (95%) use Trypticase-Soy (TS) agar. 12 (55%) units subcontract incubation to the BL.
12 units (67%) use swabs for all isolators surfaces, 5 (28%) for inappropriate surfaces to contact plates and 1 for gloves. 12 (67%) units have dry swabs impregnated with sterile diluent and 6 (33%) have pre-moistened swabs. Agar inoculation is always subcontracted to the BL (5 units – 28%); regarding the 13 other units, 5 (38%) introduce “mechanically” the media into the tube (ICR-Swab® Merck), 3 (23%) “manually” and 4 (31%) put the swab in a media tube (1 doesn’t know). Culture media are polyvalent (TS, BHI); 6 units (46%) realize agar inoculation and incubation at the pharmacy, 3 units (23%) realize agar inoculation at the pharmacy and subcontract incubation to the BL and 4 (31%) subcontract all the process.
13 units perform gloves prints: sterile (6 – 46%), neoprene (5 – 39%) or both (2 – 15%); 5 (38%) during production, 7 (54%) post-production and 1 before and after. 7 (54%) perform daily sampling, 4 (31%) weekly and 2 (15%) monthly.

Discussion & Conclusion
More than 80% of the units use contact plates and half of them combine contact plates, swabs and gloves prints. This first benchmark helps us to improve our internal practices: combination of contact plates (weekly), pre-moistened swabs (monthly) and gloves prints.

See the poster