Introduction

According to the currently accepted diagnostic criteria of the American College of Rheumatology (ACR), reactive arthritis is a sterile immune-mediated pathogenesis process of the joint that follows bacterial infection of either the gastrointestinal or urogenital system.(1) The enteric organisms most closely associated with the disease include various species of the genera Salmonella, Yersinia, Campylobacter, Shigella, and others; the primary urogenital pathogen involved in the genesis of reactive arthritis is the obligate intracellular bacterium Chlamydia trachomatis.2 Recent studies from many laboratories, however, have equivocated this official disease definition.(1) For example, while it does appear to be the case that synovial inflammation elicited by prior infection with Salmonella, Yersinia, and other enteric organisms involves primarily protein antigens in the joint rather than viable bacteria,(3-5) C. trachomatis has been demonstrated to be not only viable at that site, but also metabolically active.(6,7) Thus, as developed in detail below, our current understanding of the pathogenesis process, and host-pathogen interaction, in reactive arthritis clearly is incomplete.

Importantly, several groups have identified organisms in the inflamed joints of patients with reactive arthritis other than those canonical species specified by the official ACR definition. One approach employed by many investigators has been to use generalized polymerase chain reaction (PCR) primer systems targeting highly conserved DNA sequence regions separated by unique regions of the bacterial 16S rRNA genes. Results of the many studies structured in this fashion have been surprisingly congruent, demonstrating various species of

JUDITH A. WHITTUM-HUDSON and ALAN P. HUDSON • Wayne State University School of Medicine, Detroit, Michigan. RALPH SCHUMACHER • University of Pennsylvania School of Medicine and D.V.A. Medical Center, Philadelphia, Pennsylvania.

Pseudomonas, Mycoplasma, and other genera known to include both pathogenic and nonpathogenic organisms.(8) Interestingly, some of these studies also identified unusual bacterial species in the inflamed joint, including Moraxella osloen-sis, Stenotrophomonas maltophilia, and others, some of which are opportunistic pathogens of emerging interest.(9) However, it is not clear at this point what influence, if any, these organisms exert on the initiation or maintenance of synovial pathogenesis. A second approach to identification of noncanonical bacterial species in the joint has been to use PCR primer systems targeting a specific organism. One bacterium targeted in this manner in recent studies has been the respiratory pathogen Chlamydia pneumoniae. As developed in this chapter, C. pneumoniae has undergone relatively intense scrutiny in relation to its potential role in eliciting synovial inflammation and its resulting chronic reactive arthritis. The results of those studies indicate that this organism does indeed participate actively in the inflammatory process characteristic of this clinical entity, although many important details concerning how it does so remain to be elucidated.

Arthritis Relief Now

Arthritis Relief Now

When you hear the word arthritis, images of painful hands and joints comes into play. Few people fully understand arthritis and this guide is dedicated to anyone suffering with this chronic condition and wants relief now.

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