An expanding population of bacterial strains that are drug resistant, including methicillin-resistant Staphylococcus aureus (MRSA), will be the most important justification for nucleic acid-based tests (NAT). According to "Infectious Disease Diagnostic Markets," a new report from leading life science market research company Kalorama Information, the most substantial growth in the $8.4 billion market for infectious disease diagnostics is in molecular testing.
The needs of infectious disease testing are such that the two traditional methods, culture-based assays and immunoassays, are becoming increasingly inadequate. One key reason for this is the increase in drug-resistant infections. Immunoassays have no analytical potential here and culture-based assays for bacterial susceptibility/sensitivity, though low cost, are slow and often difficult.
"Relevancy is established through significantly improved efficacy and not marginal improvement," says Bruce Carlson, publisher of Kalorama Information. "NAT testing can be put to many uses, but what will get it into more labs is its role in determining the genetic differences that make a bacterial strain such as MRSA or MDR-TB/XDR-TB drug resistant, with results in 2-4 hours."
This has allowed physicians to more rapidly select combination therapeutics for infections such as these. And in viral applications, for example in HIV infection, it has been equally valuable in detecting drug resistances that have developed in response to therapy.
What will cause immunoassays and culture-based assays to remain in the laboratory will be their relatively low cost. The cost of NAT assays, which are not usually analyzed outside the hospital lab, is still high at around $25-$35, while selective media cost about $5 a plate.