Hemolysins and other characteristics that help differentiate and biotype Staphylococcus lugdunensis and Staphylococcus schleiferi

Abstract

Reference strains and clinical isolates representing the newly defined species Staphylococcus lugdunensis and Staphylococcus schleiferi were examined with the battery of tests previously recommended (G.A. Hébert, C.G. Crowder, G.A. Hancock, W.R. Jarvis, and C. Thornsberry, J. Clin. Microbiol. 26:1939-1949, 1988) for other species of coagulase-negative staphylococci (CNS). The Staph-Ident system (Analytab Products, Plainview, N.Y.) supplemented with tests for synergistic hemolysis, adherence to glass, pyroglutamyl-beta-naphthylamide hydrolysis, and susceptibility to a set of five antimicrobial disks differentiated each of these species from other species of CNS and separated strains within each species into several biotypes. Most strains (95%) of S. lugdunensis produced a delta hemolysin like that seen with nine other species of CNS. Most strains (91%) of S. schleiferi produced a beta hemolysin, which is a unique characteristic among CNS. Most (95%) of the S. schleiferi but very few (12%) of the S. lugdunensis were adherence positive. Both hemolysins and adherins are potential virulence factors among CNS. Some (29%) of the S. lugdunensis were beta-lactamase positive. The S. lugdunensis were resistant to polymyxin B and bacitracin (10 U), but the S. schleiferi were susceptible to both disks. Clinical isolates of S. lugdunensis were aligned in 18 biotypes because of eight biochemical profiles and eight physiologic subtypes; isolates of S. schleiferi were in 8 biotypes because of three biochemical profiles and subtypes. These tools for correctly identifying and then biotyping two more clinical species of CNS should enhance both epidemiologic and ecologic investigations.