Septic arthritis due to methylcyllin-resistant Staphylococcus aureus in adults.

INTRODUCTION

Septic arthritis due to methylcyllin resistant Staphylococcus aureus (MRSA) is a serious infection that has increased in incidence in the past 10years.

METHODS

We conducted a retrospective study (1984-2011) in which a description of the clinical and epidemiological characteristics of MRSA arthritis in adults was performed and then compared to native joint infections caused by MRSA vs. methylcyllin sensitive Staphylococcus aureus (MSSA).

RESULTS

Fourteen MRSA infections were included (7 native joint, 5 prosthetic and 2 bursae). No case was polyarticular. There was significant comorbidity, although none was associated to rheumatoid arthritis. Seven patients had bacteremia. Four required surgical treatment. Six died. When comparing the 7 patients with native joint MRSA infection with the 17 cases caused by MSSA, no significant differences in risk factors were seen, except more malignancies in the MRSA group. The infection was polyarticular in 7 cases (41%) of the MSSA group. Bacteremia was more frequent in the MRSA group (71.4 vs 58.8%). Empirical antibiotic was useful in 28.6% of MRSA cases versus 100% of MSSA cases. There was a greater tendency to associated mortality in MRSA arthritis (57.1% vs 17.6%, P=.07).

CONCLUSIONS

MRSA septic arthritis is a serious condition that occurs in the elderly and patients with high comorbidity. It is usually monoarticular, with positive blood cultures and higher mortality than MSSA arthritis. In patients at risk, vancomycin empiric antibiotic therapy is indicated.