The evaluation of Xpert MTB/RIF for the diagnosis of tuberculous meningitis / 中华检验医学杂志

ABSTRACT

Objective To evaluate the diagnostic performance of Xpert MTB/RIF for the diagnosis of tuberculous meningitis (TBM).Methods This was a prospective, single center clinical trial.A total of 116 consecutive patients with suspected meningitis who were admitted to Xijing Hospital from October 2013 to June 2015 were recruited.Mycobacterium tuberculosis ( MTB) and rifampicin ( RIF) resistance mutations in 1 ml cerebrospinal fluid ( CSF) were detected with Xpert MTB/RIF and the remaining sample was tested by Ziehl-Neelsen staining , MGIT960 liquid culture and other laboratory tests .And the enrolled patients were grouped according to the 2010 South African expert consensus .The diagnostic performance of Xpert MTB/RIF was evaluated by comparing against clinical score >5 points and MGIT960 liquid culture as reference standards respectively .The comparison was performed using a χ2 test or Fisher′s exact test for categorical variables and a nonparametric rank sum test for continuous variables .Results Among the enrolled 116 subjects, 23 subjects were diagnosed as definite-TBM by MGIT960 liquid culture, 16 subjects were classified as probable TBM , 27 subjects were classified as possible TBM , and 50 subjects were classified as non-TBM.When clinical score >5 points was used as a reference standard , the sensitivity of Xpert MTB/RIF (39.4%) was comparable with that of MGIT960 liquid culture (34.8%) (χ2 =0.292, P=0.589), and significantly better than that of Ziehl-Neelsen staining (9.9%) (χ2 =16.500, 12.771, P<0.001). No significant differences were found among the specificities of Xpert MTB /RIF, MGIT960 liquid culture and Ziehl-Neelsen staining ( 98.0%, 100.0% vs 98.0%, χ2 =1.014, P=0.602 ) .When tested against MGIT960 liquid culture as a reference standard , the sensitivity of Xpert MTB/RIF was 91.3%. Conclusions Xpert MTB/RIF is a rapid and specific method to detect MTB and RIF resistance in CSF .It exhibits a good rule in value for the diagnosis of TBM and a comparable sensitivity with MGIT 960 liquid culture, thus it can be used as the initial method for the diagnosis of tuberculous meningitis .