Rapid identification of microorganisms by circular-intensity differential scattering

There is a pressing need in clinical medicine for rapid identification of microorganisms. We describe a method that has the potential for such rapid identification: circular-intensity differential scattering, which is based on the differential scattering of left and right circularly polarized light. The scanning time required to obtain the spectral signature of an organism is about 4 min. Using a commercial circular dichrograph modified to measure circular intensity differential scattering at 90 degrees, we obtained significantly different spectra for five different crude influenza viruses. Salmonella typhimurium TA98 and TA100, and Escherichia coli HB101, HB101(pBR322), and HB101(pMB9). Purified supercoiled plasmid pBR322 DNA was readily distinguishable from linear pBR322 DNA; such differences in nucleic acid packaging may be significant factors in the discriminatory power of this technique.