1. Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605-4321;,
2. Department of Microbiology and Immunology and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia 30322
3. Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center, Decatur, Georgia 30033;
4. Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland 20814-4799;