摘要目的 观察和分析MTB对对硝基苯甲酸(PNB)的耐受情况,为实验室鉴定分枝杆菌菌种提供依据.方法 菌株来源为广州市胸科医院门诊和住院患者,从1449株分枝杆菌中确定MTB菌株1114株,对PNB培养基上生长的分枝杆菌,采用MPB64单克隆抗体试剂或进行传统生化试验,以区分MTB和非结核分枝杆菌群(NTM).实验组菌株58株为在PNB培养基上生长的分枝杆菌,但经传统生化试验义疑似MTB,经传统生化试验证实为MTB菌株后,再进行PNB最小抑菌浓度(MIC)试验,以观察其对PNB的耐受性;对照组菌株10株为在PNB鉴别培养基上不生长,经传统生化试验证实为MTB菌株;另选择H37Rv标准株和鸟分枝杆菌标准株及5株临床NTM分离株进行PNB药物的MIC值检测.两组间比较采用成组t值检验.结果 MTB菌株对PNB的耐药率为5.21%(58/1114),实验组菌株PNB的MIC值为1.0～1.5 g/L,而对照组PNB的MIC值为0.25～0.5 g/L,H37Rv标准株PNB的MIC值为0.25g/L,鸟分枝杆菌标准株和5株NTM临床分离株PNB的MIC则＞2.0g/L,实验组与其他各组比较,差异均有统计学意义(t值为4.87～6.68,均P＜0.01).结论 在采用PNB培养基进行分枝杆菌菌群初筛时,如出现菌株对PNB耐药,但菌落形态呈米黄色、粗糙呈菜花样 等,以及对一线抗结核药物敏感等符合MTB的特征时,必须进行传统的生化试验,或使用MPB64单克隆抗体试验进行菌型鉴定,或利用MTB对温度较为敏感的特点及药敏结果进行判断,以免将MTB误判为NTM导致误诊.

abstractsObjective To investigate the resistance of Mycobacterium tuberculosis ( MTB ) to p-nitrobenzoic acid ( PNB ), in order to provide the scientific basis for reliable identification of laboratory strains of mycobacterium. Methods Strains of mycobacterium grown in PNB media were identified with additional traditional biochemical tests, according to the standard protocols of laboratory diagnostics for tuberculosis by the Chinese Antituberculosis Association. For mycobacteria grown in the PNB media but highly suspected as MTB by traditional biochemical tests, MPB64 monoclonal antibody was used for the differentiation between MTB and non-tuberculosis mycobacteria group ( NTM ). Minimal inhibitory concentrations ( MIC ) of PNB was further determined for culture-confirmed MTB, 10 strains of clinically isolated MTB ( control ), H37 Rv standard strain, mycobacterium avium standard strain, and 5 strains of clinically isolated NTM. Results A total of 1114 strains of MTB were confirmed, among which 58 PNB manifested resistance. The rate of resistance was 5.21% ( 58/1114 ), with an MIC ranging for 1. 0 - 1.5g/L. The MICs of control MTB and H37 Rv standard strain were 0. 25 - 0. 5 g/L and 0. 25 g/L, respectively.Both mycobacterium avium standard strain and clinically isolated NTM showed an MIC of ＞ 2. 0 g/L.Differences between groups were statistically significant ( t = 4. 87, 5.09, 6. 68, respectively, P ＜ 0. 01 ).Conclusion In order to avoid laboratory misdiagnosis, for primary screening with NTB with PNB culture,the presence of MTB characteristics, including cream-colored broccoli-like colony morphologies, as well as clinical response to first-line anti-tuberculosis medications, despite PNB tolerance, warrants further investigations of traditional biochemical tests, differentiation with MPB64 monoclonal antibodies, or simply by the use of temperature manipulation or drug-sensitivity test results.