With many organizations taking monthly surface sampling in-house, it makes sense that they plan to incubate the surface samples as well. The 2008 version of USP <797> essentially let organizations get away with having only one incubator, which was used for the incubation of gloved fingertip samples at 30 to 35°C and then anything that needed to be incubated at 20 to 25°C was left on a shelf or counter at “controlled room temperature”. This will no longer be acceptable and the incubation of all tests and samples must be in an incubator.
Let’s look at what you need to consider when choosing an incubator.
- Appropriate interior and exterior size – You must know how much will be in the incubator at any given time, including media-fill and gloved fingertip tests and surface samples. Knowing the exterior dimensions is also important, so you can ensure you have the necessary space.
- Temperatures – One incubator needs to be able to heat to 30 to 35 °C and the other needs to be able to refrigerate to 20 to 25 °C. Yes, it needs to be able to refrigerate. Incubators work by drawing in ambient air and then depending on the design, either it heats the air or it can heat or cool the air. To be able to maintain the 20 to 25°C range, a refrigerated incubator is recommended. And no, putting the incubator in a room kept colder than 20°C doesn’t work.
- Forced air – For the incubation of microbiological samples for USP <797>, all that is needed is a forced air incubator. It doesn’t need to be CO2 or water jacketed.
- Easy to read display – It’s nice having a digital display to know what the temperature is inside the chamber.
- Installation – Make sure you have the appropriate space. Many require a certain clearance around all sides. The incubators must also be kept outside of the compounding environment. It is strongly recommended that you have dedicated space for the incubators, away from other pharmacy activities.
- Maintenance – Follow the manufacturer’s preventative maintenance recommendations. This could include checking the gaskets for damage or making sure the incubator is level so that the door will self-close.
- Temperature monitoring – The incubator’s temperature must be monitored daily. This can be done by reading the digital display, reading another thermometer that is placed inside the incubator, or through an automated, continuous monitoring device. No matter which is chosen, the method must be calibrated.
- Calibration – The incubator must be calibrated at least annually unless the manufacturer requires a more frequent calibration interval.
- Qualification – It is strongly recommended that a full installation, operation, and performance qualification be performed on the incubators, but this may be more than the pharmacy wishes to take on. At a minimum, have the incubators temperature mapped to at least identify any hot or cold spots.
- Cleaning schedule – Define a cleaning schedule for the incubator. Be sure to check the manufacturer’s instructions for compatible agents and other cleaning considerations.
By taking on incubation of samples, the pharmacy is essentially also becoming a microbiology lab. Be sure to review USP <1117> Microbiological Best Laboratory Practices. Also be sure to check out our other blog titled “Determining How You Will Handle Viable Sampling and Incubation.”
Pure Microbiology is here to help. Reach out with questions related to viable sampling and incubation.