Influenza Testing

We have purchased the Bianax Now Influenza A&B test kits. The Vendor had indicated the appropriate CPT would be 87804 at 2 units (as we are testing for both A&B strains). However, we are finding that some Payer edits will not allow 2 units and are recommending billing the CPT twice with a 59 modifier. Our question is :
What is the difference between CPT 87804 and 87400 (Influenza A or B) and can either code be billed with # of units or do both require a 59 mod?

Rapid Flu Test

Code 87804 is detection by visual interpretation. If tested for A and B, then bill code 87804 twice and put modifier -59 on second code. This test takes a sample from respiratory tract (throat, nose, sputum). This service is coded per result. 1 result = one code, 2 results = 2 codes. payers differ on modifiers, if they do not accept modifier -59, append modifier -91 (Repeat diagnostic test).

Code 87400 is taken fron any other source, by culture or any technique not considered rapid flu test.

Nancy Maguire