Spore Strip Population Testing
Microtest has demonstrated substantial expertise at biological spore strip population testing. This procedure is performed according to the United States Pharmacopeia (USP), Section <55>.
 Testing involves strips pre-inoculated with certain spores. At issue: do the strips actually possess specified spore counts? If so, they can be passed for use as biological indicators in later testing. The USP requires that customers submit a minimum of three indicators per test.
In the population test, the USP specifies three strips per evaluation. Strips are placed into sterile diluent, and then mechanically macerated. Diluted solution containing the chewed-up material is heat shocked plated so as to achieve a target of 30 to 300 colonies per plate, and incubated for 48 hours to encourage spore growth.
All culture media used undergoes USP Growth Promotion Testing (GPT) and sterility assurance for optimal recovery and sterility. Incubators are calibrated and monitored 24/7 via our lab’s advanced SCADA system. Positive and negative controls are performed with each sample.
Finally, plate counts are enumerated, and populations for each spore strip are calculated. Per the USP, the average number of colonies recovered should be not less than 50% and not more than 300% of the strip’s label claim. If population levels are acceptable for every lot, these strips can then be used to test the efficacy of ethylene oxide, steam, and dry heat sterilization processes.
At Microtest, the entire test can usually be reported in 1 week. And of course, all testing is performed by qualified microbiologists.
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