OBJECTIVE To explore the diagnostic value of the guanylate binding protein 5 (GBP5) gene in patients infected with Mycobacterium tuberculosis (MTB).

METHODS Patients who visited the Fifth People′s Hospital of Suzhou from Jan. 2024 to May 2024, as well as individuals undergoing health examinations during the same period, were selected as the study subjects. Based on the diagnostic criteria, the subjects were divided into active tuberculosis (ATB) group (230 cases), pneumonia group (207 cases), latent tuberculosis infection (LTBI) group (48 cases) and healthy control (HC) group (122 cases). Real-time quantitative reverse transcription polymerase chain reaction was used to detect the expression level of the GBP5 gene in the whole blood of the subjects, and receiver operating characteristic (ROC) curves were employed to analyze its diagnostic performance.

RESULTS There were statistically significant differences in GBP5 gene expression among the four groups (P < 0.001). The area under the ROC curve (AUC) for GBP5 in distinguishing the ATB group from the HC group, LTBI group and pneumonia group was 0.902, 0.813 and 0.745, respectively. In the ATB group, the positive detection rate of the GBP5 method was 67.39%, higher than that of Gene Xpert MTB/RIF (62.20%), tuberculosis culture (60.00%) and smear acid-fast staining (35.20%) (P < 0.05). When distinguishing between ATB and LTBI patients, the positive prediction value of GBP5 was 95.09%, higher than that of IGRA testing (79.92%) (P < 0.05). The expression level of GBP5 was negatively correlated with the MTB bacterial load (P < 0.001).

CONCLUSIONS The detection of the GBP5 gene has important clinical significance in the auxiliary diagnosis of tuberculosis and can serve as an effective supplement to existing diagnostic methods for tuberculosis.