Characteristics of spontaneous coagulase-negative staphylococcal spondylodiscitis: a retrospective comparative study versus Staphylococcus aureus spondylodiscitis.

Background: Coagulase-negative staphylococci (CoNS) are increasingly implicated in recent patient series of spondylodiscitis, but there are no series of CoNS-spondylodiscitis available. The objective of this study was to compare the characteristics of patients with spontaneous CoNS-spondylodiscitis with those patients with Staphylococcus aureus (SA) spondylodiscitis.

Methods: This was a retrospective single center study involving 147 spontaneous infectious spondylodiscitis cases observed between 2000 and 2015. The 26 cases of CoNS-spondylodiscitis (15 confirmed) were compared with 30 cases of SA-spondylodiscitis. CoNS infection was considered confirmed if the same CoNS was isolated in at least two samples at two different times.

Result: Patients with CoNS-spondylodiscitis were older (70 vs. 61 years of age; p = 0.01), had associated cancer more often (15% vs. 0%; p = 0.04) and had a longer diagnostic delay (>15 days in 88% vs. 60%; p = 0.01); experienced fever less often (19% vs. 50%; p = 0.01), and had lower white blood cell (7.6 vs. 9.9G/L; p = 0.01) and polymorphonuclear leucocyte counts (5.6 vs. 7.5G/L; p = 0.04). Patients with CoNS spondylodiscitis had less pronounced inflammatory syndrome (erythrocyte sedimentation rate [ESR]: 62 vs. 81 mm at 1 h; p = 0.03; CRP: 60 vs. 147 mg/L; p = 0.0003) and less common (ESR < 30 mm: 23% vs. 0%; p = 0.01; CRP < 10 mg/L: 23% vs. 0%; p = 0.005) in comparison with patients with SA infection. The infection entry site was most often an intravascular catheter (20% vs. 3%; p = 0.008). The level of positive percutaneous needle biopsies was comparable between CoNS and SA. Two patients who died both had SA infections.

Conclusion: CoNS-spondylodiscitis involved at least 10% of spontaneous spondylodiscitis cases and was more common in elderly patients, afflicted by comorbidities, and its presentation was less virulent than that of those with SA-spondylodiscitis.