Microbiologic Testing for 503A Sterile-Compounding Pharmacies

Compounding pharmacists must ensure that the sterile preparations they dispense are free of microbiologic contamination. Working in a cleanroom under controlled conditions (proper differential air pressure, temperature, and humidity; acceptable levels of viable and nonviable airborne particles and surface counts, etc.) and testing the efficacy of cleaning and disinfecting practices via environmental monitoring (viable-air and surface testing, glove-fingertip-thumb testing, etc.) are essential to preparing contamination-free medications. Sterile-compounding pharmacists must understand how to monitor their cleanroom environment and, if they perform testing in house, to interpret the results of simple microbiologic tests (a skill helpful even when tests are outsourced to a contract laboratory). In this article, which pertains to 503A sterile compounding, and is based on the current version of United States Pharmacopeia (USP) Chapter <797>, basic concepts in microbiology and the microbial tests that can be performed and interpreted in house and those that must be outsourced are discussed. Streamlining communication with contract laboratory personnel is reviewed. Requirements for an inhouse microbiology laboratory are presented, and the advantages and disadvantages of inhouse and outsourced testing are examined. A list of suggested reading is provided for easy reference. In a subsequent article, environmental monitoring and analysis will be addressed in detail.