Near-infrared spectrometry of microorganisms in liquid pharmaceuticals

Biotechnology and pharmaceutical research have created a number of new and potentially life-saving drugs. Many of these drugs are formulated as injectable products. Some drug products do not survive autoclaving or other means of terminal sterilization. An aseptic filling process is typically used to sterilize such products, but it is less reliable than autoclaving, making detection of unsterile units even more essential. Invasive microbiological methods and turbidimetry are currently employed as inspection techniques. These processes are time-consuming, destroy product, and may not detect low levels of contamination. Near-IR light scattering is proposed as a new method of determining low levels of contamination noninvasively and nondestructively. The method is used successfully in the current study to detect contamination by a species of yeast, mold, and bacteria in intact plastic infusion bags at levels as low as three colony-forming units per milliliter for yeast. By use of the near-IR method, each injectable unit can be evaluated with its integrity maintained, allowing the product to be dispensed or evaluated by another analytical method.