两种血培养系统的需氧与厌氧瓶对模拟菌血症标本检测能力的对比研究

Controlled comparison of two supplemented aerobic and anaerobic blood culture bottles to detect simulated bacteremia specimens

目的 对比BACTEC Plus需氧、厌氧血培养瓶和BacT／ALERTFA需氧瓶、FN厌氧瓶对模拟菌血症标本的检测能力。方法 采用健康献血者的5ml无菌新鲜血液和定量菌液组成模拟菌血症标本202组，其中112组标本中加入定量抗菌药物以模拟患者接受抗菌药物治疗的情况。比较需氧瓶检测需氧菌、厌氧瓶检测专性厌氧菌和兼性厌氧菌，以及需氧瓶检测含有抗菌药物的需氧菌标本的平均检测时间（time-to-detect，TTD）和阳性率。结果 两种需氧瓶对需氧菌检测阳性率均为100％，对于10^2、10^3CFU／ml两种浓度菌液，BACTEC Plus需氧瓶平均TTD分别为（13．69±3．74）h、（11．54±2．87）h，快于BacT／ALERTFA瓶平均TTD的（16．76±5．62）h、（14．47±4．30）h，两者比较差异有统计学意义（t=-5．674、-7．294，P〈0．01）。对于专性厌氧菌，BACTEC Plus氧瓶和Bac T/ALERT FN瓶阳性率分别为92％和100％，BacT／ALERTFN瓶的平均TTD分别为（22．60±9．16）h、（22．10±13．46）h，快于BACTECP1US厌氧瓶平均TTD的（40．24±35．07）h、（34．88±17．34）h，两者比较差异有统计学意义（t=2．389、2．712，P〈0．05）。对于兼性厌氧菌，BACTEC Plus厌氧瓶和BacT／ALERTFN瓶阳性率分别为100％和60％，BACTEC Plus厌氧的平均TTD为（13．24±7．82）h、（11．33±7．61）h，明显快于BacT／ALERTFN瓶平均TTD的（16．79±8．00）h、（19．27±14．71）h，两者比较差异有统计学意义（t=-3．440、-2．604，P〈0．05）。对含有抗菌药物的需氧菌标本，BACTEC Plus需氧瓶和BacT／ALERTFA瓶阳性率分别为100％和57％，BACTECPlus需氧瓶TTD多快于BacT／ALERT FA瓶。加入抗菌药物会延长TTD，且延长时间和两种培养的TrD时间差随抗菌药物浓度的增加而延长。结论 应根据患者的情况选择不同的血培养系统和培养瓶。对怀疑需氧菌或兼性厌氧菌感染，以及在进行血培养时已接受抗菌药物治疗的患者，选用BACTEC Plus需氧、厌氧血培养瓶；对怀疑厌氧菌感染的患者选用BacT／ALERTFN厌氧血培养瓶，能够更快地检出病原菌，并提高血培养阳性率。

Objective To compare BACTEC Plus aerobic and anaerobic bottles with BacT/ALERT FA aerobic bottles and FN anaerobic bottles in the ability of detecting simulated bacteremia specimens. Methods The 202 pairs of specimens were composed of 5ml sterile blood and defined loads of microorganisms. 112 pairs of specimens in them also contained defined doses of antibiotics to simulate the patients undertaking antibiotic therapy. Time-to-detect （ TTD ） and positive percentages were evaluated in four groups, including aerobic bottles detecting aerobic bacteria, anaerobic bottles detecting anaerobic bacteria and facuhative anaerobic bacteria, and aerobic bottles contained antibiotics detecting aerobic bacteria. Results The positive percentages of two kinds of aerobic bottles were both 100%. For the specimens with bacterial concentration of 10^2 and 10^3 CFU/ml, average TTDs of BACTEC Plus aerobic bottles [ （ 13.69 ± 3.74 ） h, （ 11.54± 2. 87 ） h ] were faster than those of BacT/ALERT FA bottles [ （16.76±5.62） h, （14.47 ±4.30） h; t= -5.674,-7.294,P〈0.01].To anerobic bacteria, the positive percentages of BACTEC Plus anaerobic bottles and BaeT/ALERT FN bottles were 92% and 100%, respectively. Average TI＇Ds of BacT/ALERT FN bottles [ （ 22. 60 ± 9. 16 ） h, （ 22. 10 ± 13.46 ） h ] were faster than those of BACTEC Plus anaerobic bottles [ （40.24 ± 35.07 ） h, （ 34. 88 ± 17.34） h ; t = 2. 389, 2. 712, P 〈 0. 05 ]. To facultative anaerobic bacteria, the positive percentages of BACTEC Plus anaerobic bottles and BacT/ALERT FN bottles were 100% and 60%, respectively. Average TTDs of BACTEC Plus anaerobic bottles[ （ 13.24 ±7. 82） h, （ 11.33 ±7. 61 ） h]were faster than those of BacT/ALERT FN bottles [ （ 16.79 ± 8.00） h, （ 19. 27 ± 14. 71 ） h; t = - 3. 440, - 2. 604, P 〈 0. 05 ]. To the specimens containing antibiotics, the positive percentages of BACTEC Plus aerobic bottles and BacT/ALERT FA bottles were 100% and 57%, respectively. Most TTDs of BACTEC Plus aerobic bottles were faster than those of BacT/ ALERT FA bottles. The addition of antibiotics delayed the TTDs, and the more the antibiotics specimens contained, the slower the TTDs was. Conclusions According to the condition of the patients, different blood culture bottles and systems should be selected to shorten the TTDs and enhance the positive percentage. To the patient maybe infected with aerobic or facultative aerobic bacteria and those undertaking antibiotic therapy, BACTEC Plus aerobic and anaerobic bottles are recommended to be used. To the patients maybe infected with anaerobic bacteria, BacT/ALERT FN bottles are recommended to be used.