超声分散比浊法处理BACTEC MGIT 960培养阳性的菌液标本用于药物敏感性试验的价值

Application value of sonication nephelometer for culture-positive bacterial samples with the BACTEC MGIT 960 system for drug sensitivity test

目的分析应用超声分散比浊法处理的BACTEC MGIT 960(简称“MGIT 960”)培养阳性的液体培养物菌液标本用于分枝杆菌药物敏感性试验(简称“药敏试验”)的价值。方法搜集2018年1—12月西安市胸科医院经MGIT 960液体分枝杆菌培养阳性的标本,共计1086份。其中,818份菌液标本进行MGIT 960 液体药敏试验,包括MGIT 960推荐方法处理的菌液标本100份、超声分散比浊法处理的菌液标本718份;268份菌液标本进行比例法药敏试验,包括采用传统磨菌法处理的菌液标本30份、超声分散比浊法处理的菌液标本238份。与传统菌液标本处理方法比较,分析超声分散比浊法处理后的菌液标本用于MGIT 960液体药敏试验和比例法药敏试验的效果。结果超声分散比浊法处理后的0.6~1.0麦氏单位菌液标本进行MGIT 960液体药敏试验报告结果的时间主要集中在8~10d,而MGIT 960法处理后的菌液标本报告结果时间则较均匀分布在5~14d。浊度为0.6、0.7、0.8、0.9、1.0麦氏单位菌液标本系统检测X200(标本活菌量少)报告率[分别为0.00%、0.00%、0.00%、0.72%(1/138)、1.31%(2/153)]均低于MGIT 960菌液处理法[11.00%(11/100)],差异均有统计学意义(χ^2值分别为11.41、9.94、12.43、12.79、11.28,P值均<0.01)。进行二线抗结核药物比例法药敏试验时,增菌6~7d后,应用超声分散比浊法处理的菌液标本基本可以达到目标浊度,而传统磨菌法处理的标本在增菌第7天时仅有80%达到目标浊度。应用超声分散比浊法处理后的浊度为0.7、0.8、0.9、1.0麦氏单位的菌液标本,药敏试验成功率分别为82.61%(19/23)、82.69%(43/52)、94.00%(47/50)、96.00%(48/50),与传统磨菌法处理的菌液标本药敏试验成功率[83.33%(25/30)]相近,差异均无统计学意义(χ^2值分别为0.01、0.01、2.37、3.77,P值均>0.05)。结论应用超声分散比浊法处理MGIT 960液体培养阳性的菌液标本,可提高MGIT 960液体药敏试验成功率,缩短比例法药敏试验时间。

Objective This study aimed to analyze the application value of culture-positive bacterial samples with the BACTEC MGIT 960 system (referred as “MGIT 960 system ”) prepared by sonication nephelometer method for the drug sensitivity test (DST) of mycobacteria. Methods A total of 1086 culture-positive mycobacteria samples detected by MGIT 960 system were collected in Xi’an Chest Hospital from January to December 2018. Among these samples, 818 bacterial samples underwent DST using MGIT 960 system, including 100 samples treated by MGIT 960 system recommended method and 718 samples treated by sonication nephelometer;and 268 bacterial samples conducted DST with the proportional method, including 30 samples treated by the traditional grinding method and 238 samples treated by the sonication nephelometer. The values of the bacterial samples treated by sonication nephelometer for DST detected by MGIT 960 system and the proportional method were compared with traditional bacterial samples. Results The results of DST using the MGIT 960 system for 0.6-1.0 McFarland standards samples treated by the sonication nephelometer were mainly reported on 8-10 days. The bacterial samples treated by the MGIT 960 system were evenly reported on 5-14 days. The reporting rates of the system X200 (small amount of live bacteria) of 0.6, 0.7, 0.8, 0.9, 1.0 McFarland standards samples by sonication nephelometer treatment method (0.00%, 0.00%, 0.00%, 0.72%(1/138), 1.31%(2/153), respectively) were lower than that treated by MGIT 960 method (11.00%, 11/100), with the statistically significant differences (χ^2=11.41, 9.94, 12.43, 12.79, 11.28, all P<0.01). When the second-line DST with the proportional method was carried out, the bacterial sample treated by sonication nephelometer basically reached the target turbidity after 6 to 7 days of enrichment, while the bacterial sample treated by traditional grinding method only reached 80% of the target turbidity on the 7th day of enrichment. The bacterial samples with the turbidity of 0.7, 0.8, 0.9, and 1.0 McFarland standards was treated by sonication nephelometer, and the success rate of DST was 82.61%(19/23), 82.69%(43/52), and 94.00%(47/50), 96.00%(48/50), respectively, which was similar to the success rate of the DST of the bacterial samples treated by the traditional grinding method (83.33%, 25/30), without the statistically significant differences (χ^2=0.01, 0.01, 2.37, 3.77, all P>0.05). Conclusion The MGIT 960 culture-positive bacterial samples that treated by sonication nephelometer can improve the success rate of DST by MGIT 960 system, and shorten the detection time of DST with the proportional method.