title: Comparison of real-time PCR and conventional biochemical methods for identification of Staphylococcus lugdunensis.
abstract: Staphylococcus lugdunensis is an aggressive, virulent member of the coagulase-negative staphylococci (CoNS) that is responsible for severe, rapidly progressive skin and soft tissue infections and native valve endocarditis. To facilitate prompt identification and appropriate therapy, we describe here a rapid and robust multiplex real-time PCR assay that is able to definitively distinguish S. lugdunensis from other staphylococci. Using melting curve analysis, the assay also identifies Staphylococcus aureus and CoNS other than S. lugdunensis and determines MecA-dependent resistance to methicillin (meticillin). When applied to a panel of well-characterized staphylococcal reference strains, as well as 165 clinical isolates previously identified by conventional methods, the assay was both sensitive and specific for S. lugdunensis, correctly identifying the reference strain and all 47 S. lugdunensis isolates without inappropriate amplification of other staphylococci. Furthermore, rapid biochemical identification using the WEE-TAB system to detect ornithine decarboxylase activity was found to be unsuitable as an alternative to PCR identification, displaying just 31% sensitivity and 77% specificity when tested on a subset (90 isolates) of the clinical strains. We therefore propose that this simple, accurate PCR approach will allow for the routine and timely identification of S. lugdunensis in the clinical microbiology laboratory.
authors.affiliation: Stanford University School of Medicine, Department of Pathology, 300 Pasteur Drive, Lane 235, Stanford, CA 94305-5324, USA. bpinsky@stanford.edu
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Pinsky
authors.forename: Divinia
authors.initials: D
authors.lastname: Samson
authors.forename: Laleh
authors.initials: L
authors.lastname: Ghafghaichi
authors.forename: Ellen J
authors.initials: EJ
authors.lastname: Baron
authors.forename: Niaz
authors.initials: N
authors.lastname: Banaei
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015373:Bacterial Typing Techniques / Q000379:methods*; D004269:DNA, Bacterial / Q000235:genetics; D006801:Humans; D009955:Ornithine Decarboxylase / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013210:Staphylococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D044366:Transition Temperature
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D009955:Ornithine Decarboxylase