The bacterial loads of air, surfaces, and personnel in clean rooms are rout
inely monitored using a set of standard media. Bacteria that can grow on th
ese media are a tiny fraction of the total numbers in any environment. A su
bstantial proportion of bacteria long thought to be unculturable were recen
tly shown to be oligophilic. Oligophile counts in clean rooms in our studie
s exceeded the standard plate counts by up to 2 orders of magnitude. They r
esponded to disinfection routines in ways similar to the responses of conve
ntional bacteria. We suggest that oligophiles are better tools than convent
ional bacteria for environmental monitoring in aseptic pharmaceutical produ
ction units.