Found the following
(U. S. Department of Health and Human Services, 2010) considers cheese made with pasteurized milk as adulterated if the cheese contains 104 1014 CFU/g S. aureus or B. cereus or 100 CFU/g E. coli; 1015 these lots should be rejected and additional investigation conducted. If enterotoxin is detected, 1016 the product should be destroyed.
Alkaline phosphatase level in pasteurized fluid bovine milk is limited to less than 2.0 1087 micrograms phenol equivalent per gram in one or more subsamples whereas cheeses may have higher limits. Actionable limits for S. aureus and B. cereus are set to 104 1088 CFU/g whereas limits 1089 for E. coli or coliforms are set based for specific products. Pathogens such as Salmonella, E. coli 1090 O157:H7, or L. monocytogenes are considered adulterants in RTE dairy products.
https://www.fsis.usd...pdf?MOD=AJPERES
American cheese includes the following varieties of cheese: (a) Cheddar cheese and cheddar cheese for manufacturing shall conform to the provisions of 21 CFR 133.113 and 133.114, respectively, “Cheeses and Related Cheese Products,” as issued by the Food and Drug Administration. (b) Washed curd cheese (soaked curd cheese) and washed curd cheese for manufacturing shall conform to the provisions of 21 CFR 133.136 and 133.137, respectively, “Cheeses and Related Cheese Products,” as issued by the Food and Drug Administration. © Granular cheese (stirred curd cheese) and granular cheese for manufacturing shall conform to the provisions of 21 CFR 133.144 and 133.145, respectively, “Cheeses and Related Cheese Products,” as issued by the Food and Drug Administration. (d) Colby cheese and colby cheese for manufacturing shall conform to the provisions of 21 CFR 133.118 and 133.119, respectively, “Cheeses and Related Cheese Products,” as issued by the Food and Drug Administration
https://www.ams.usda...Standard[1].pdf
So since they've define what "american" cheese is, following the standards for american cheese limits should do the trick
From what I can tell, because there is no standard of identity for curds, there are no specific limits for anything