Certain bacterial species can survive extended periods of dessication, by forming resistant endospores. Clostridia and anthrax are the most famous examples, what with all your terrorist-ey types sending anthrax spores through the mail to whoever happens to be on their shit list du jour that day. Its not so much the bacteria themselves, its anthrax bacteria after having enveloped itself in a spore, resistant to dessication, and other harsh conditions otherwise inimical to the bacteria themselves. When such endospores find themselves in a warm, moist environment such as after having been inhaled, say, in soil, or somewhere that handles sheep hides, then once they've found a nice comfortable (for the anthrax bacteria, not the host, that is) spot, such as a lung, the endospores then germinate, allowing further replication of the bacteria in a more ideal habitat than wherever it was that they formerly were which required sporulation in the first place.
Which is not to suggest your pills are contaminated with anthrax, merely pointing out that some such microorganisms can indeed survive extended periods of dessication.