Are blood cultures performed after disco-vertebral biopsy useful in patients with pyogenic infective spondylitis?

A. Cherasse, D. Martin1, C. Tavernier and J. F. Maillefert

Departments of Rheumatology and
1 Neuroradiology, Dijon University Hospital, France

SIR, As the treatment of pyogenic infective spondylitis is based on appropriate antibiotic therapy, the identification of the causative micro-organism is highly desirable. Thus, the investigations performed prior to initiation of therapy must include blood and, if negative, disco-vertebral biopsy cultures [1]. Moreover, since it is thought that such biopsies can result in transient blood bacteriaemia, additional blood cultures in the minutes and hours following the biopsy are often recommended. However, to our knowledge, the usefulness of post-biopsy blood cultures has never been assessed. The aim of this work was to evaluate the diagnostic value of such blood cultures.

For this purpose, the data of every patient hospitalized in our rheumatology unit between 1991 and 2001 for pyogenic infective spondylitis were retrospectively reviewed. The diagnosis was made in the presence of clinical, laboratory and imaging (including bone scintigraphy and/or CT scan and/or magnetic resonance imaging) evidence of pyogenic infective spondylitis, and (i) the presence of micro-organism on blood culture and/or disco-vertebral biopsy, or (ii) the efficacy of empirical antibiotic treatment on clinical, laboratory and imaging parameters. Among these patients, the characteristics of those in whom a disco-vertebral biopsy was performed were reviewed.

During the evaluation period, 56 patients were hospitalized for pyogenic infective spondylitis. Among these, a percutaneous X-ray guided disco-vertebral biopsy was performed in 35 whose pre-biopsy blood cultures were negative. The characteristics of these 35 patients are shown in Table 1Go. Of the 35 biopsy cultures, 24 (68.6%) were positive. In all patients, three additional blood cultures were performed from 30 min to 4 h following the biopsy. These cultures were considered as positive if at least two out of three revealed the same micro-organism. Of the 35 patients, blood cultures performed after disco-vertebral biopsies were positive in 7 (20%). In one patient, for whom all other cultures, including those obtained from disco-vertebral biopsy, were negative, a positive blood culture was of great therapeutic interest, as it revealed Esherichia coli. In five other patients, the causative micro-organism had been isolated from the disco-vertebral biopsy cultures, but the positive blood culture was of therapeutic interest, in that it revealed a previously observed uncommon and/or saprophytic micro-organism (Staphylococcus epidermidis in three patients, Capnocytophaga in one, and Pyocyanic bacillus in two). Thus, the blood cultures made it possible to conclude that the micro-organism obtained on disco-vertebral biopsy was not due to contamination, and was involved in the vertebral infection.


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TABLE 1. Characteristics of the 35 patients

 
The population evaluated in this study was comparable with others previously published in terms of age, gender, localization of the vertebral infection, bacteriological performance of the disco-vertebral biopsy and causative micro-organisms [1, 2]. These results suggest that blood cultures following disco-vertebral biopsy may sometimes be helpful in the diagnosis of pyogenic infective spondylitis. This easy to perform, cheap, non-aggressive procedure sometimes confirms difficult bacteriological diagnoses. Moreover, it allows identification of the causative micro-organism in some patients in whom all previous procedures, including disco-vertebral biopsy cultures, are negative.

Conflict of interest

The authors have declared no conflicts of interest.

Notes

Correspondence to: J. F. Maillefert, Department of Rheumatology, Hôpital Général, 3 rue du Fb Raines, 21000 Dijon, France. E-mail: jean-francis.maillefert{at}chu-dijon.fr Back

References

  1. Colmenero JD, Jiménez-Mejias ME, Sanchez-Lora FJ et al. Pyogenic, tuberculous, and brucellar vertebral osteomyelitis: a descriptive and comparative study of 219 cases. Ann Rheum Dis 1997;56:709–15.[Abstract/Free Full Text]
  2. Honan M, White W, Eisenberg GM. Spontaneous infection discitis in adults. Am J Med 1996;100:85–9.[ISI][Medline]
Accepted 28 November 2002





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