How is sterility testing performed for pharmaceutical products?

Sterility testing demonstrates absence of viable microorganisms per pharmacopeial methods (USP <71>, Ph. Eur. 2.6.1). Methods include: membrane filtration (preferred - filtering product through 0.45 um membrane, incubating membrane in growth media) and direct inoculation (adding product directly to media - used when filtration is impractical). Media: tryptic soy broth (bacteria, fungi) and fluid thioglycollate medium (aerobic and anaerobic bacteria). Incubation: 14 days at appropriate temperatures. Validation includes: method suitability testing (demonstrating recovery of challenge organisms), media growth promotion testing, and bacteriostasis/fungistasis testing. Positive and negative controls verify test validity. Personnel performing sterility testing require qualification and environmental monitoring during testing.