浙江省宁波市耐多药结核分枝杆菌吡嗪酰胺耐药特征及与二线抗结核药物耐药关系

目的研究结核分枝杆菌(MTB)对吡嗪酰胺耐药特征及其与二线抗结核药物耐药相关性。方法以2015-2017年浙江省宁波地区结核病耐药监测收集的110例耐多药结核病(MDR-TB)病例作为研究对象,采用1%比例法对其进行5种二线抗结核药物(氧氟沙星、左氧氟沙星、卡那霉素、阿米卡星、卷曲霉素)的耐药检测。同时应用BACTEC MGIT 960系统检测所有MDR-MTB的吡嗪酰胺耐药性,采用PCR DNA直接测序法检测MDR-MTB的pncA基因突变特征。结果110株MDRMTB中吡嗪酰胺耐药率为59.09%(65/110),pncA基因突变率为50.91%(56/110)。吡嗪酰胺耐药株中的基因突变率83.08%(54/65)与吡嗪酰胺敏感株中的基因突变率4.44%(2/45)比较,差异有统计学意义(χ^2=65.787,P<0.001)。pncA基因突变类型为42种,以点突变类型为主92.86%(39/42)。耐链霉素、耐乙胺丁醇、耐氧氟沙星、耐左氧氟沙星及准广泛耐药(PreXDR)与MDR-MTB耐吡嗪酰胺相关。结论本地区MDR-MTB耐吡嗪酰胺形势较为严峻,MDR-MTB耐吡嗪酰胺与二线抗结核药物氧氟沙星、左氧氟沙星及Pre-XDR的耐药相关。

Characteristics of Pyrazinamide resistance in multidrug-resistant Mycobacterium tuberculosis and its correlation with second-line drug resistance

ObjectiveTo investigate the characteristics of the resistance to Pyrazinamide in multidrug-resistant (MDR) Mycobacterium tuberculosis（MTB） strains and its correlation with the second-line drug resistance in Ningbo.MethodsA total of 110 MDR-TB isolates selected in the drug resistance survey in Ningbo between 2015 and 2017 were used in the study. The conventional drug susceptibility test (1% ratio method) was used to detect the drug-resistant profiles of MDR-MTB against 5 second-line antibiotics (ofloxacin, levofloxacin, kanamycin, amikacin, capreomycin). BACTEC MGIT 960 PZA method was used to detect Pyrazinamide resistance of 110 MDR-MTB isolates and gene sequencing was conducted to detect the mutation of pncA gene.ResultsAmong the 110 isolates of MDR-MTB, 65 were resistant to Pyrazinamide (59.09%). pncA gene mutation occurred in 56 strains of MDR-MTB (50.91%). Among the 65 Pyrazinamide resistant strains, pncA mutation was detected in 54 strains (83.08%). Among the 45 Pyrazinamide sensitive strains, pncA mutation was detected in 2 strains (4.44%). The mutation rate of pncA was much higher in Pyrazinamide resistant strains than in Pyrazinamide sensitive strains, the difference was significant (χ2＝65.787, P＜0.001). There were 42 mutation types in pncA gene, and single base substitution was the main type (92.86%). The resistance to streptomycin, ethambutol, ofloxacin, levofloxacin and pre-extensive drug resistance (pre-XDR) were associated with Pyrazinamide resistance in MDR-MTB strains.ConclusionMDR-MTB clinical isolates were resistant to Pyrazinamide seriously, and the Pyrazinamide resistance was associated with the resistances to second line antibiotics (ofloxacin, levofloxacin) and pre-XDR.