Prevalence of Tuberculous Spondylodisciitis and Diagnostic Utility of Xpert MTB RIF

Abstract

Background

To understand the prevalence of TB spondylodisciitis and the diagnostic utility of Xpert MTB RIF test (Genexpert) in the diagnosis of TB spondylodisciitis as compared with a Composite Reference Standard (CRS) based on clinical, mycobacterial smear, culture, pathological, radiological findings and clinical follow up.

Methods

69 patients with infective spondylodisciitis who underwent surgical or image guided tissue biopsy were evaluated during May 2014 to February 2017. Tuberculous spondylodisciiitis were classified as ‘confirmed’ if culture grew MTB, ‘probable’ if in the absence of positive AFB culture, clinical, radiological or pathological findings favor TB, ‘possible’ if all negative but response to ATT was noted.

Results

36 patient had culture confirmed pyogenic spondylodisciitis; 17 cases were treated empirically though the tissue culture were negative as HPE was suggestive of pyogenic spondylodisciitis. 3 had non-infective etiology.

Among 30 who were treated as tuberculous spondylosdisciitis, in initial 16 patients genexpert was not done due to non-availability. Among these 16 patients, 1 had confirmed TB as the tissue grew MTB (MDR TB), 15 were treated as probable TB. All patients except one had good outcome. In the 14 patients treated as tuberculous spondylodisciitis in whom genexpert was done, 12 patients had positive genexpert as compared with 7 AFB culture positive patients. In two samples in which genexpert was negative, TB was confirmed by AFB culture and in another by HPE. All patients except one (who had underling lymphoma) improved with ATT. In all other 10 cases where genexpert was negative, the etiology was pyogenic.

Conclusion

Pyogenic spondylodisciitis is more prevalent than tuberculous spondylodisciits in this study. Genexpert in tissue from infective spondylodisciitis is more sensitive than AFB smear and culture in diagnosing tuberculous spondylodisciitis.

Table 1:

Performance of Genexpert as compared with AFB culture

	genexpert +	genexpert -
Culture –	6	1
Culture +	6	1

Figure 1:

Flow chart depicting distribution of cases and genexpert performance

Disclosures

All authors: No reported disclosures.