FPGEE for National Association of Boards of Pharmacy (NABP) Practice Exam

What is the method of choice for sterility testing when feasible?

1. Direct inoculation of culture medium

2. Membrane filtration method

3. Visual inspection under magnification

4. Incubation at room temperature

The correct answer is: Membrane filtration method

The membrane filtration method is the preferred method for sterility testing when it is feasible. This technique is particularly effective because it can efficiently capture microorganisms from larger volumes of liquid, such as solution or culture media, that need to be tested for sterility. In this method, the liquid sample is passed through a filter that has a pore size small enough to retain bacteria and fungi while allowing the liquid to pass through. After filtration, the filter is then placed on or in appropriate culture media, where any trapped microorganisms can grow, allowing for detection of contamination. This method offers several advantages, including its capacity to test larger volumes and its ability to provide a quantitative measure of microbial burden if needed. It also minimizes the risks of contamination that can sometimes occur with other testing methods. Other methods, while useful in certain contexts, do not provide the same level of reliability and efficiency. For instance, direct inoculation of culture medium might be simpler but is less sensitive when dealing with low levels of contamination. Visual inspection under magnification is not a reliable method for detecting microbial contamination as many microorganisms cannot be seen without culturing, and it may miss low levels of pathogens. Incubation at room temperature is not a standard practice for sterility testing since specific temperature conditions