| Objective: Our study aimed to evaluate the clinic application value of traditional phenotypic drug susceptibility,pyrazinase(pyrazinase,PZase)activity and pnc A gene mutation in the detection of pyrazinamide(pyrazinamide,PZA)resistance on the basis of analyzing the high-risk populations,which may provide theoretical and laboratory data for clinical detection of PZA resistance.Methods: TB patients were collected in the Affiliated Hospital of Zunyi Medical University from July 2018 to July 2019.A total of 1921 positive clinical isolates were obtained after acid-fast staining and Mycobacterium tuberculosis(M.tb)culture,of which1123 isolates were selected for drug sensitivity test according to the principle of selecting only one sample from multiple samples of the same patients.A total of 157 clinical isolates were randomly selected from different drug-resistant strains for inclusion in this study,including 73 cases of fully sensitive bacteria,7 cases of isoniazid-resistant bacteria,8 cases of rifampicin-resistant bacteria,and MDR-TB 69 cases of mycobacteria.All the 157 clinical isolates were tested for PZA phenotypic drug sensitivity,and the drug resistance ratio of PZA in different drug-resistant isolates were analyzed.Univariate and multivariate logistic regression analysis was carried out according to the age,sex,history of initial treatment and drug resistance types of clinical patients,to identify the risk factors of PZA drug resistance and to find out the high-risk population of PZA resistance.At the same time,in order to evaluate the method for testing PZA resistance,based on the PZA phenotype sensitivity,the PZase enzyme activity testing and pnc A gene sequencing were performed in157 clinical isolates,and comprehensive analysis to evaluate the reliability of PZA drug resistance detection methods in clinical application.Results:(1)The phenotypic drug sensitivity of PZA showed that,among the 157 clinical isolates,52 cases were PZA-resistant,whereas 105 cases were PZA-sensitive.The ratio of PZA resistance among all sensitive bacteria was 12.3%(9/73),the ratio of PZA resistance among INH mono-resistant bacteria was 28.5%(2/7),and the ratio of PZA resistance among RIF-resistant bacteria was 75.0%(6/8),the PZA resistance ratio in MDR bacteria is50.7%(35/69).The resistance ratio of PZA in male patients was 32.1%(34/106),while that in female patients was 35.3%(18/51).The resistance ratio of PZA in new cases and retreated cases were 26.3%(25/95)and 43.5%(27/62),respectively.(2)Compared with patients less than 30 years old,patients older than 30 years old are protective factors for PZA resistance.Retreatment,RIF single resistance and MDR-TB were risk factors for PZA resistance(OR> 1,P <0.05),while the gender,initial treatment and INH single resistance were not risk factors for PZA resistance.Further logistic regression analysis showed that RIF mono-drug resistance(OR=26.61;95%CI:4.21-168.24)and MDR-TB(OR=6.17;95%CI: 2.42-15.76)were still significantly associated with PZA resistance,whereas the gender,single-drug resistance in INH,and history of treatment were not the risk factors of PZA drug resistance.(3)Using two or more consistent results among the three methods as the evaluation criteria of PZA drug sensitivity,PZase activity test and pnc A molecular sequencing were 87.2%,91.2%,and 100%,respectively,while the specificity of which were 84.8%,91.9% and99.3%,respectively.The positive 95.2%,97.4% and 100%,respectively.The Kappa values consistent with the reference results were 0.65,0.77 and 0.84,respectively.Conclusion: MDR-TB and RIF single resistance were risk factors for PZA resistance.Compared with the PZA phenotypic drug sensitivity test and PZase activity test,the pnc A gene sequencing method has more clinical application value for the detection of PZA resistance. |
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