To retrospectively analyze the clinical and laboratory characteristics of patients with positive blood culture results for Mycobacterium tuberculosis (M.tb).

The clinical laboratory database of patients suspected with disseminated tuberculosis from January 2009 to January 2017 in Huashan Hospital affiliated with Fudan University were collected and analyzed. The clinical manifestations, laboratory characteristics and outcomes between disseminated tuberculosis patients with positive blood culture (positive blood culture group) for M. tb and negative results (negative blood culture group) were compared. T test, Mann-Whitney U test and Fisher exact test were used for statistical analysis.

A total of 5 589 patients suspected with M. tb infection had peripheral blood culture for mycobacterium. Positive blood culture for M. tb was found in 26 disseminated tuberculosis patients, while 6 patients finally identified as nontuberculous mycobacterium (NTM) with species identification, and 22 disseminated tuberculosis patients with negative blood culture results were enrolled during the same period as control. The mean age ([49.1±10.1] years old vs[38.3±17.1] years old, t=2.460, P=0.018), the proportion of diagnosed with fever of unknown origin at admission (FUO) (65.0%[13/20] vs 13.6%[3/22], P=0.001), the proportion of diagnosed with focal infection (30.0%[6/20] vs 86.4%[19/22], P=0.001), the proportion of patients with other diseases (75.0%[15/20] vs 22.7%[5/22], P=0.002), the proportion of patients with hematological diseases (35.0%[7/20] vs 4.5%[1/22], P=0.018) and the proportion of patients with tumor (20%[4/20] vs 0[0/22], P=0.043) in the positive blood culture group were significantly different from those in the negative blood culture group. Laboratory examinations of the percentage of neutrophils, the percentage of lymphocytes, the percentage of monocytes, the value of neutrophil/lymphocyte, the level of hemoglobin, the level of erythrocyte sedimentation rate, the level of C-reactive protein, the level of procalcitonin and the positive rate of T-SPOT.TB in positive blood culture groups were significantly different from those in negative blood culture group (all P<0.05).

Peripheral blood M. tb culture is more likely to be positive for those elder disseminated tuberculosis patients with hematological diseases or tumors, and those with increase of neutrophil counts and inflammation markers but reduction of lymphocyte counts and hemoglobin.

Mycobacterium tuberculosis; Blood culture; Disseminated tuberculosis