Abstract： Objective　To analyze the species distribution of microorganisms in culture tubes reported positive byBACTEC™ MGIT960 (hereafter referred to as "MGIT960") after species identification using matrix-assisted laser desorption/ionization time of flight massspectrometry (MALDI-TOF MS) technique. Methods　From 2021 to 2022, a total of 2 662 positive tubes reported by the MGIT 960 instrument at Tuberculosis Reference Laboratory of Tianjin Center for Tuberculosis Control were collected. Liquid cultures were independently inoculated to blood plate and neutral L-J medium, and the resulting isolate strains were identified using the MALDI-TOF MS method. According to the MALDI-TOF MS results, the non-repetitive results of the same patient on the same culture medium were analyzed for the composition ratio of strain distribution. For the strains not identified by MALDI-TOF MS, 38 strains were selected for 16S rRNA gene sequencing. Results　A total of 605 isolates were obtained from blood plates, and 501 of those were analyzed. Among them, Mycobacterium accounted for 17.76% (89/501), predominant by Mycobacterium abscess 10.18% (51/501) and Mycobacterium fortuitum 3.19% (16/501). Bacteria other than Mycobacterium accounted for 68.06% (341/501), with the main ones being Nocardia farcinica 15.57% (78/501), Gordonia sputa 9.38% (47/501) and Gordonia bronchialis 7.58% (38/501). There were 71 unidentifiable strains, making up 14.17% (71/501). A total of 2 378 strains were isolated from neutral L-J mediums, 1 748 of which were used in the incoming analysis. Among these, 78.72% (1 376/1 748) were Mycobacterium, 60.53% (1 058/1 748) were Mycobacterium tuberculosis (MTB), 4.69% (82/1 748) were Mycobacterium chimaer intracellulare group and 3.55% (62/1 748) were Mycobacterium Lentiflavum. Bacteria other than Mycobacterium accounted for 17.11% (299/1 748) in neutral L-J medium isolates, with Nocardia farcinica 4.35% (76/1 748), Gordonia sputa 2.69% (47/1 748) and Gordonia bronchialis 2.12% (37/1 748) as the main species. There were 73 strains that couldn't be identified, comprising 4.18% (73/1 748). The 38 strains that not identified by MALDI-TOF MS were all found to be Actinobacteria and Firmicutes by sequencing. Conclusions　A variety of nontuberculous Mycobacterium and bacteria other than Mycobacterium were found in the positive culture tubes reported by the MGIT960 instrument, most of which could be quickly identified by mass spectrometry. Bacteria other than Mycobacterium are mainly Nocardia and Gordonia, which should be paid attention to in differential diagnosis.

Objectives To explore the associations between drug efflux pump gene expression and phenotypic drug resistance as well as gene mutation patterns related to drug resistance of Mycobacterium tuberculosis.Methods Forty-five Mycobacterium tuberculosis isolates resistant to one or more of drugs including isoniazid, rifampicin, streptomycin and ethambutol, and 26 isolates all sensitive to the above four drugs from Tianjin Tuberculosis Control Institute in 2007 were involved in this study. Direct sequencing was applied to detect the mutations in the corresponding resistance genes(isoniazid:katG, inhA, oxyR-ahpC, ndh, rifampicin:rpoB, streptomycin:rpsL, rrs, and ethambutol:embB, embC and embA). After RNA extration and reverse transcription, real-time PCR was conducted to assess the expressions of putative drug efflux pump genes Rv1410c, Rv2136c, Rv0783c and Rv2136c, and Students' t test and ANOVA analysis were used to analyze the expression differences in Mycobacterium tuberculosis with different phenotypic drug resistance and drug resistance related gene mutation patterns.Results Compared to pan-sensitive isolates[(5.67±3.29)×10-5], Rv1410c showed higher expression in streptomycin[(8.48±6.33)×10-5, t'=2.18, P<0.05], isoniazid[(8.43±6.38)×10-5, t'=2.20, P<0.05], rifampicin[(9.59±7.27)×10-5, t'=2.29, P<0.05], multi-drug[(10.37±7.86)×10-5, t'=2.34, P<0.05] resistant isolates, and in isoniazid + streptomycin resistant isolates[(9.39±6.81)×10-5, t'=2.43, P<0.05];Rv2136c showed higher expression in isoniazid resistant[(3.51±2.43)×10-5, t'=2.03, P<0.05], multidrug-resistant isolates[(4.21±2.94)×10-5, t'=2.22, P<0.05] and resistant to isoniazid+streptomycin[(3.81±2.46)×10-5, t'=2.28, P<0.05] isolates . The expression of Rv0783c in rifampicin resistant isolates with rpoB 531 mutations [(5.41±3.03)×10-6] was higher than those with wild type of rpoB 531[(2.29±1.62)×10-6, t=2.81, P<0.05].Conclusions The expression of Rv1410c and Rv2136c are associated with mutiple-drug resistance of Mycobacterium tuberculosis.The expression of Rv0783c in rifampicin resistant isolates is associated with mutation in rpoB 531.

Objective　To investigate the correlation between degree of deeper infiltration of NPC on CT scan,prognosis and expression of P53 protein,in order to further recognize bilogical features of NPC.Methods　Collect 70 NPC biopsy specimens,which had performed CT scan before radiotherapy and had detailed clinical records.The expression of P53 protein was examined by means of S-P immunohistochemical technique.The correlation between expression of P53 protein and peripheral deeper infiltration and prognosis was analysed in detailed.Results　The results of these cases showed that the positive rate of over expression P53 were 68.57%,which had no relation with the histological types and pathological grades.The positive rate of P53 in Ⅱ、Ⅲ types had a higher positive rate than that of the Ⅰ type of NPC.Expression of P53 protein had no relation with neck lymph node metastasis,but had significant correlation with the size of metastatic lymph node,which is the positive rate of P53 in diameter of metastatic lymph node ＜4 cm was higher than that of diameter ≥4 cm.Expression of P53 had no relation with local recurrence and distant metastasis after radiotherapy.Conclusion　With the tumor infiltrating the deeper layer of nasopharynx,the positive rate of P53 expression is more and more high,and degree of malignant is increasing.The three types on CT scan represents the biological features of NPC.