GAS-LIQUID-CHROMATOGRAPHY OF CELLULAR FATTY-ACIDS FOR IDENTIFICATION OF STAPHYLOCOCCI

A commercially available, computer-assisted microbial identification s ystem (MIS) employs gas-liquid chromatographic analyses of bacterial f atty acids. The MIS was used to identify 470 isolates of Staphylococcu s species. The accuracy of the MIS was compared with the accuracies of conventional methods. There was a complete agreement between the MIS and conventional methods in the identification of 413 (87.8%) strains. For 36 of 45 misidentified strains, the correct identification was li sted by the MIS as a choice but not as the first choice. Twelve strain s could not be matched. All strains of Staphylococcus cohnii, S. epide rmidis, S. intermedius, S. lugdunensis, S. schleiferi, S. sciuri, S. s imulans, and S. xylosus were correctly identified. Two species, S. hom inis and S. saprophyticus, accounted for 52.6% (30 of 57) of the misid entifications. Seventy eight organisms were retested. Identification o f 73 organisms remained unchanged, and for five organisms, the second choice became first and vice versa. The overall performance of the MIS is acceptable, and the system can be used as an alternate identificat ion method for staphylococci.