Msc Ing. Ambiental

MINIREVIEW

Osteomyelitis and the role of bio¢lms in chronic infection
Rebecca A. Brady1, Jeff G. Leid2, Jason H. Calhoun3, J. William Costerton4 & Mark E. Shirtliff1,5
1

Department of Microbiology and Immunology, University of Maryland – Baltimore, School of Medicine, Baltimore, MD, USA; 2Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA; 3Department ofOrthopaedic Surgery, University of Missouri – Columbia, Columbia, MO, USA; 4 Center for Biofilms, School of Dentistry University of Southern California, Los Angeles, CA, USA; and 5Department of Biomedical Sciences, University of Maryland – Baltimore, Dental School, Baltimore, MD, USA

Correspondence: Mark E. Shirtliff, Department of Biomedical Sciences, Dental School, University ofMaryland-Baltimore, 650 W. Baltimore Street, Rm 9209, Baltimore, MD 21201, USA. Tel.: 1410 706 2263; fax: 1410 706 0865; e-mail: mshirtliff@umaryland.edu Received 2 July 2007; revised 28 September 2007; accepted 30 September 2007. First published online 13 December 2007. DOI:10.1111/j.1574-695X.2007.00357.x Editor: Willem van Leeuwen Keywords osteomyelitis; biofilm; Staphylococcus aureus .

AbstractUnderstanding the mechanisms implicated in the initial attachment, development, and maturation of a biofilm phenotype are of tremendous importance for their effect on the medical, industrial, and public health arenas. This review explores the current understanding of the nature of biofilms and the impact that molecular interactions between the bacteria themselves, as well as between bacteria and the host, mayhave on biofilm development and phenotype using the nonmotile Gram-positive coccus, Staphylococcus aureus, as an example .

Introduction
Osteomyelitis is defined as an infection of the bone (Mader et al., 1997). The pathogenesis of osteomyelitis has been explored clinically and different types of osteomyelitis can be classified according to the source of the infection (i.e. hematogenous orcontiguous focus) and the vascular capability of the host (i.e. with or without generalized vascular insufficiency) (Lew & Waldvogel, 2004).

Types and causes of osteomyelitis
Hematogenous osteomyelitis
Hematogenous osteomyelitis, which is caused by the seeding of bacteria from the bloodstream, accounts for 20% of osteomyelitis cases. Primary hematogenous osteomyelitis is caused by the direct seedingof bone from a bacterial species in the blood. Although found in the adult population, it is more predominant in infants and children (Lew & Waldvogel, 2004). Hematogenous osteomyelitis in adults is more commonly caused by secondary infection where the bacteria gain access to the bloodstream and seed distal bone and
FEMS Immunol Med Microbiol 52 (2008) 13–22

marrow sites. Infections are alsocaused by the reactivation of a quiescent focus of hematogenous osteomyelitis that developed in infancy or childhood and ‘arrested.’ The most common site of involvement is the distal part of the tibia, and the lesion is typically single and located near the metaphysis. There are two common types of hematogenous osteomyelitis: Long bone and vertebral osteomyelitis. Both are most often caused by asingle bacterial species (discussed later), though vertebral osteomyelitis secondary to trauma may be polymicrobic. Patients generally present with fever, lethargy, tenderness over the infection site, and decreased range of motion (Carek et al., 2001). In long bone osteomyelitis, the metaphyses of the long bones (tibia, femur) are most frequently involved (Shirtliff et al., 1999), which is explainedby the anatomy of the metaphyseal region. Here, the blood flow becomes sluggish and disordered. The slowing of blood flow allows bacteria to settle and initiate colonization and an inflammatory response. Minor trauma likely predisposes the infant or child to infection by producing a small hematoma, vascular obstruction, and a subsequent bone necrosis that is susceptible to inoculation from a...