Comparison oftheAutoSCAN-W/A RapidBacterial Identification SystemandtheVitek AutoMicrobic Systemfor Identification ofGram-Negative Bacilli

TheautoSCAN-W/A (W/A; Baxter MicroScan, WestSacramento, Calif.) withthenewfluorometric Rapid Neg Combo1(RNC)panel isafully automated fluorometric system foridentification ofbothenteric andnonenteric gram-negative bacilli within 2h.Wecompared theW/AwiththeVitek AutoMicrobic System (Vitek AMS;Vitek Systems, Inc., Hazelwood, Mo.)foridentification of383clinical isolates ofgram-negative bacilli. TheAPI20E (Analytab Products, Plainview, N.Y.) andconventional biochemical testing wereusedasthereference systems. TheW/Acorrectly identified 336isolates (87.7%) tothespecies level andclassified anadditional 29isolates (7.6%) ascorrect withlowprobability (overall identification = 95.3%); theVitek AMS correctly identified 355 isolates (92.7%) tothespecies level andclassified anadditional 8isolates (2.1%) ascorrect withlowprobability (overall identification = 94.8%). A commonsetof134isolates ofgram-negative bacilli wastested inboth participating laboratories asameansofassessing interlaboratory agreement withboththeW/AandtheVitek AMS.Theoverall agreements between thetwolaboratories were86%withtheW/Aand92%withtheVitek AMS.TheW/Aperformed comparably totheVitek AMSforidentification ofmostgram-negative bacilli, actually exceeding theVitek AMS foridentification ofnonenteric bacilli. Rapidtimetoidentification andahighlevel of automation maketheW/Aanattractive system forclinical microbiology laboratories. Diagnosis andtherapy ofgram-negative bacterial infection inhospitalized patients remains amajor challenge forclinical microbiology laboratories. Thecontinued prominence of gram-negative bacilli asmajorpathogens inintensive care unit patients (14), development oflimited-spectrum antibioticsandantibiotic-resis tant