When monitoring environments in pharma industry I check separately the total aerobic mesophilic count (TAMC) in TSA and total yeast and molds count (TYMC) in Sabouraud (SDA) with an air sampler.
The guidelines show only one limit. It is a general limit for total microbial contamination which should be >200 UFC/m3. Is the total microbial contamination the count of TAMC plus TYMC?? I mean, if I check microorganisms that grow in TSA and SDA my total count should be the addition of both? Or should I consider only the TSA plate due to TSA is a culture for bacteria and fungi?
To combine counts, you must ensure you're not double counting - fungi will grow on TSA and bacteria on Sabouraud. As you wondered, TSA alone might be just as good. You could use a medium with reduced Aw designed to recover fungi unlikely to grow on TSA. Think the limit number should be less than (). There are article in Am Pharma Rev on this subject - e.g. https://www.americanpharmaceuticalreview.com/Featured-Articles/169384-Role-of-Environmental-Monitoring-and-Microbiological-Testing-During-Manufacture-of-Sterile-Drugs-and-Biologics/
Thank you for your reply Phil Geis . First of all, the limit is .
If I use only one culture for the count of bacteria and fungi I will probably undervalue one of them because if I incubate TSA at 30-35 ºC this is the optimal temperature for bacteria which will grow faster than fungi. On the other hand If I incubate at 24 ºC is the optimal temperature for fungi. So, wouldn't it be better gorwth each type of microorganism in their respective cultures and count both?
At one time - folks used on plate incubated initially at 35 C and later at 24 for bacteria and fungi respectively. As you might anticipate, the plate often dried out making it unacceptable. You can use 2 plates one at each temp. - whatever the media, this demands you discern potential double counting.
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