title: Identification of staphylococci by Phoenix: validation of a new protocol and comparison with Vitek 2.
abstract: Because of their frequent isolation in the routine laboratory and their increasing clinical significance, fast and accurate species identification of staphylococci may be required; this can only be achieved by automated systems. A total of 147 clinical isolates (52 Staphylococcus aureus, 50 Staphylococcus epidermidis, and 45 other coagulase-negative staphylococci [CoNS]) were first identified by molecular methodology and then comparatively tested by Vitek 2 (new colorimetric identification card) and Phoenix using the novel 0.25 McFarland and the standard 0.50 McFarland inoculum protocols. All S. aureus isolates were accurately identified. Vitek 2 identified correctly all S. epidermidis and 93.3% of the other CoNS, whereas the respective rates were 86% and 82.2% for Phoenix's standard and 92% and 82.2% for the novel protocol. It appears that both systems provide excellent identification of S. aureus, but Vitek 2 recognizes CoNS species more accurately than Phoenix. The 0.25 McFarland protocol does not improve system performance.
authors.affiliation: Laboratory of Clinical Microbiology, Attikon Hospital, National and Kapodistrian University of Athens, Haidari, Athens, Greece.
authors.forename: Kalliopi-Stavroula
authors.initials: KS
authors.lastname: Chatzigeorgiou
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Siafakas
authors.forename: Efthymia
authors.initials: E
authors.lastname: Petinaki
authors.forename: Athina
authors.initials: A
authors.lastname: Argyropoulou
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Tarpatzi
authors.forename: Maria
authors.initials: M
authors.lastname: Bobola
authors.forename: Olga
authors.initials: O
authors.lastname: Paniara
authors.forename: Aristea
authors.initials: A
authors.lastname: Velegraki
authors.forename: Loukia
authors.initials: L
authors.lastname: Zerva
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015373:Bacterial Typing Techniques / Q000295:instrumentation / Q000379:methods*; D001431:Bacteriological Techniques; D003030:Coagulase / Q000032:analysis; D006801:Humans; D008826:Microbial Sensitivity Tests; D011933:Reagent Kits, Diagnostic; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D013212:Staphylococcus epidermidis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D003030:Coagulase; D011933:Reagent Kits, Diagnostic