Session Information
Session Type: ACR Poster Session B
Session Time: 9:00AM-11:00AM
Background/Purpose: The incidence of methicillin-resistant Staphylococcus aureus (MRSA) septic arthritis (SA) has increased over the past decade. While MRSA SA is thought to be more severe than non-MRSA SA, there is little published evidence suggesting these patients differ in their presentation and outcomes in the adult population. Our objective: To define the epidemiology, clinical characteristics and outcomes of patients with MRSA SA compared to non-MRSA SA patients.
Methods: We conducted a retrospective study that included all patients 18 and older admitted to a single, tertiary-care hospital between 1998 and 2015 diagnosed with culture-positive monoarticular SA and were surgically treated. We excluded cases of osteomyelitis, polyarticular infection or septic bursitis.
Results: Of the 425 patients with SA, 63 (14.8%) were due to MRSA. Compared to patients with non-MRSA SA, those with MRSA SA: were older (63.2 vs 58.3 years, p=0.04); had a higher prevalence of chronic kidney injury (p=0.004); had more end-stage liver disease (p=0.04); and were more likely to have shoulder involvement (p=0.004). In addition, MRSA SA was more likely to affect patients with recent (0-42 days) prosthetic implantation (p=0.05). There were no significant differences in rates of fever or sepsis but mean ESR (87.5 vs 74.3 mm/hour, p=0.04) and mean % of blood polymorphonuclear (PMN) (80.4 vs 77.3%, p= 0.05) were significantly higher in those with MRSA SA. Importantly, the length of hospital stay (LOS) was significantly longer for patients with MRSA SA (12.6 vs 10.4 days, p=0.05), as well as the rates of discharge to rehabilitation was higher (73.7 vs 54%, p=0.005) and expiration within 30 days (11.4 vs 4.4 %, p=0.03).
Conclusion: MRSA SA is common, representing nearly 15% of SA cases. Our study confirms that MRSA SA patients tend to be older, have more comorbidities and worse outcomes than those infected with other organisms. Despite these findings, patients with MRSA SA do not, on average, appear to be sicker at the time of presentation. Table 1. Demographic and clinical features of patients with culture-positive septic arthritis, Methicillin-Resistant Staphylococcus Aureus (MRSA) vs. non-MRSA
| MRSA (n=63) | Non-MRSA (n=362) | p-Value | |
| Demographic Data: | |||
| Age (yrs), mean (SD) | 63.2 (19.4) | 58.3 (17.8) | 0.04 |
| Female gender, N (%) | 29 (46) | 159 (43.9) | 0.76 |
| Risk Factors for SA: | |||
| DM, N (%) | 22 (34.9) | 116 (32) | 0.65 |
| CKI, N (%) | 17 (27) | 47 (13) | 0.004 |
| HIV, N (%) | 1 (1.6) | 11 (3) | 0.52 |
| ESLD, N (%) | 5 (8) | 10 (2.8) | 0.04 |
| IVDU, N (%) | 6 (9.5) | 17 (4.7) | 0.12 |
| History of septic arthritis, N (%) | 17 (27) | 60 (16.6) | 0.05 |
| RA, N (%) | 5 (7.9) | 20 (5.5) | 0.45 |
| Previous joint trauma, N (%) | 10 (15.9) | 53 (14.6) | 0.80 |
| Recent procedure in joint, N (%) | 29 (46) | 141 (39.1) | 0.30 |
| Clinical features: | |||
| Fever (>100 F), N (%) | 23 (36.5) | 129 (35.6) | 0.78 |
| Sepsis (defined by SIRS criteria), N (%) | 17 (27) | 121 (33.4) | 0.43 |
| Mean peripheral WBC (in thousands), (SD) | 12.3 (6.1) | 11.5 (5.2) | 0.31 |
| Mean peripheral PMN (%), (SD) | 80.4 (9.9) | 77.3 (11.1) | 0.05 |
| Mean ESR (mm/hr), (SD) | 87.5 (36.4) | 74.3 (37.9) | 0.04 |
| Mean CRP (mg/L), (SD) | 151.5 (111.3) | 135.9 (105.9) | 0.40 |
| Mean synovial WBC (in thousands), (SD) | 105.6 (118.4) | 83.8 (112) | 0.22 |
| Mean synovial fluid PMN (%), (SD) | 89.4 (15.9) | 87.1 (17.8) | 0.39 |
| SD: Standard deviation; DM: Diabetes Mellitus; CKI: Chronic Kidney Injury; HIV: Human Immunodeficiency Virus; ESLD: End Stage Liver Disease; IVDU: Intravenous Drug Use; RA: Rheumatoid arthritis; WBC: White blood cell; PMN: Polymorphonuclear leukocyte; ESR: Erythrocyte sedimentation rate; CRP: C-reactive protein | |||
Table 2. Joints affected and outcomes in patients with culture-positive septic arthritis, MRSA vs. non-MRSA.
| MRSA | Non-MRSA | P-Value | |
| Joint: | |||
| Knee, N (%) | 32 (50.8) | 206 (56.9) | 0.37 |
| Hip, N (%) | 8 (12.7) | 72 (19.9) | 0.18 |
| Shoulder, N (%) | 14 (22.2) | 35 (9.7) | 0.004 |
| Infected 0-42 days of prosthetic insertion, N (%) | 6 (30) | 17 (12.8) | 0.05 |
| Infected 43-365 days of prosthetic insertion, N (%) | 6 (30) | 43 (32.3) | 0.84 |
| Infected >365 days since prosthetic insertion, N (%) | 8 (40) | 73 (54.9) | 0.21 |
| ICU, N (%) | 12 (19.4) | 59 (16.3) | 0.56 |
| Detection of pus by surgeon, N (%) | 26 (74.3) | 154 (65.8) | 0.32 |
| Mean LOS in days, N (SD) | 12.6 (9.1) | 10.4 (8.1) | 0.05 |
| Discharge to rehabilitation, N (%) | 42 (73.7) | 185 (54) | 0.005 |
| ICU: Intensive Care Unit; LOS: Length of Stay | |||
To cite this abstract in AMA style:
Fowler ML, Byrne K, Lieber SB, Moore A, Shmerling R, Paz Z. Do Patients with MRSA-Positive Septic Arthritis Differ Clinically from Non-MRSA-Positive Counterparts? [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/do-patients-with-mrsa-positive-septic-arthritis-differ-clinically-from-non-mrsa-positive-counterparts/. Accessed .« Back to 2016 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/do-patients-with-mrsa-positive-septic-arthritis-differ-clinically-from-non-mrsa-positive-counterparts/