Streptococcal septic arthritis in adults. A study of 55 cases with a literature review.

OBJECTIVES

To evaluate the rate of occurrence and characteristics of streptococcal septic arthritis.

METHODS

Retrospective single-center study of patients with bacteriologically documented septic arthritis admitted to a rheumatology department over a 20-year period.

RESULTS

Of 303 cases of septic arthritis, 55 (18%) were due to streptococci and 166 (55%) to Staphylococcus aureus (55%). As compared to patients with S. aureus arthritis, patients with streptococcal arthritis was more likely to be in female (56% vs. 36%, P < 0.006) and older than 60 years of age (71% vs. 58%), less likely to have comorbidities (36% vs. 56%), rheumatoid arthritis (5% vs. 19%, P < 0.01), or diabetes (2% vs. 15%, P < 0.01), and more likely to have cancer (13% vs. 7%). Involved joints and proportions of patients with arthritis in multiple joints were similar in two groups. Mortality was lower in the group with streptococcal infection (3.6% vs. 7.8%). The streptococci were distributed as follows: group A (n = 7), group B (n = 12), group C (n = 4), group D (n = 7), group F (n = 1), group G (n = 2), nongroupable (n = 14), nontypable (n = 1), and Streptococcus pneumoniae (n = 7). Groups A and B and nongroupable strains mainly affected women; group A selectively involved younger patients and group B very elderly patients. Comorbidity, most notably cancer, was common in patients with S. pneumoniae or group D streptococci. The portal of entry was often a skin lesion for groups A and B and a medical procedure for group D. Multiple joint involvement was common with groups A and B and prosthetic joint infection with groups B and C. Group A and S. pneumoniae were associated with severe systemic symptoms and extra articular foci of infection, whereas a smoldering course was more common with groups D and G and with nongroupable strains. Residual joint abnormalities were noted in half the patients, with no differences across groups.

CONCLUSIONS

The features of streptococcal septic arthritis vary according to the group of the causative organism and differ from those of S. aureus arthritis.