[Relationship Between the VNTR Loci Polymorphism and MALDI-TOF MS Protein Profile Diversity in Mycobacterium tuberculosis Complex].

OBJECTIVE: To study the relationship between the copy numbers of repetitive units at variable number tandem repeat (VNTR) loci of Mycobacterium tuberculosis complex (MTBC) with its diversity of protein profiles. METHODS: The MTBC strains were subjected to genotyping using multiple locus variable number tandem repeat analysis (MLVA). Also, the principal component analysis (PCA) was performed for bacterial protein profiles of MTBC using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The relationship between the polymorphism of VNTR loci and PCA clustering was analyzed. RESULTS: A total of 157 MTBC strains were collected. 146 MTBC strains (MS identification score values ≥1.700) were performed PCA and three clusters, clusterⅠ(61 strains), clusterⅡ(26 strains) and cluster Ⅲ(59 strains), were generated. Polymorphic diversities were observed in 24 VNTR loci, among them, 7 were highly various, 7 were moderately, and 10 were low various. The polymorphism of Mtub39, QUB26 and QUB4156 loci were correlated with the results of MALDI-TOF MS clustering (P=0.000, P=0.035, P=0.017). CONCLUSION: The polymorphism of Mtub39, QUB26 and QUB4156 loci in MTBC was correlated with the difference of MALDI-TOF MS protein profiles, suggesting that these loci may play a role in regulating the composition of protein profiles of MTBC strains.

[Triton X-100 Enhanced the Detection of Hodge Test and Carba NP Test for Carbapenemase-producing Acinetobacter baumannii Complex].

OBJECTIVE: To find out highly effective phenotypic methods to detect carbapenemase-producing Acinetobacter baumannii (A. baumannii complex) so as to support the epidemiological investigation and clinical application. METHODS: We included 113 A. baumannii complex and compared the detection performance of modified Hodge test, Carba NP test, Triton Hodge test, and the simplified Carba NP-direct test with Tritont X-100. RESULTS: We tested 83 carbapenemase-producing A. baumannii complex and 30 non-carbapenemase producers. The sensitivity and specificity of Hodge test were significantly higher than those of Carba NP test (71.1% versus 35.0%, 100% versus 86.7%, P<0.05, respectively). The sensitivity of Triton Hodge test and Carba NP-direct test was respectively significantly higher than Hodge test and Carba NP test (98.8% versus 71.1%, 85.5% versus 35.0%, P<0.001, respectively ). However, the specificities were comparable (P>0.05). The positive additive effects of the two methods with Triton X-100 were more obvious than those of the methods without Triton X-100 (P<0.001). CONCLUSION: Triton X-100 could increase the sensitivity and positive additive effect on phenotypic detection of A. baumannii complex. Triton Hodge test and Carba NP-direct test were more applicable for clinical routine procedure.