Group B streptococcus (Streptococcus agalactiae) pyogenic arthritis in nonpregnant adults

We analyzed the cases of pyogenic arthritis from group B streptococcus (GBS), or, in nonpregnant adults diagnosed in the Hospital Universitari de Bellvitge, a 1,000-bed tertiary care teaching hospital in Barcelona, Spain, during a 10-year period, and we reviewed the available literature to summarize the experience with this infectious entity. From the database of our institution, which does not attend pediatric, obstetric, or burn patients, we collected all microbiologically proven cases of infectious arthritis seen from January 1992 to December 2001. We excluded patients with infection limited to spine; patients with prosthetic joint infection; patients undergoing articular surgery during the year before diagnosis; and those with tuberculous, brucellar, or fungal arthritis. Of a total of 112 patients identified, GBS was the causative organism in 11 (10%) cases. We reviewed the literature using a MEDLINE search (1972-2001), and found 64 additional cases. Of the 75 patients, 34 (45%) were men and 41 (55%) women, with ages ranging from 20 to 87 years (mean age, 57.9 +/- 14.9 yr); 37 patients (49%) were over 60 years. Sixty-eight percent (51/75) of the patients presented with monoarthritis, while in 32% (24/75) more than 1 joint was involved. The most common location was the knee (36%), followed by the shoulder (25%). In 66% (43/65) of cases, bacteremia was documented. In 64% (47/74) of patients, a systemic predisposing factor for infection was noted; the most common conditions were diabetes mellitus, malignancies, and chronic liver diseases. In 31% (23/75) of patients, a concomitant infectious process due to the same microorganism was found, mainly vertebral osteomyelitis and urinary tract infection. Penicillin was the main antibiotic used after bacterial identification; surgical drainage was performed in 36% (27/75) of cases. The overall mortality rate was 9% (7/75). GBS is now a significant causative agent of pyogenic arthritis in nonpregnant adults. In this population, joint infection by GBS is a disease that mainly affects aged patients with underlying medical illnesses; polyarticular involvement, bacteremia, and the presence of a concomitant infectious process are frequent conditions. The case-fatality rate is substantial.