Department of Microbiology, Institute of Public Health Zagreb County, Zaprešić, Croatia.
Department of Clinical Microbiology, Infection Prevention and Control, Zagreb, Croatia.
J Mass Spectrom. 2024 Sep;59(9):e5080. doi: 10.1002/jms.5080.
We evaluated the performance of Zybio EXS2600 matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) (Zybio Inc., Chongqing, China) for the identification of bacteria from positive blood culture (BC) bottles using Blood Culture Positive Sample Pretreatment Kit (Zybio Inc., Chongqing, China) in comparison to an in-house saponin method. Following a positive signal by the BACTEC™ FX system, confirmation of identification was achieved using subcultured growing biomass used for MALDI-TOF MS analysis. A total of 94 positive BC bottles with 97 bacterial isolates were analyzed. The overall identification rates at the genus and species levels for the saponin method were 89.7% (87/97) and 74.2% (72/97), respectively. With the Zybio Kit, 88.7% (86/97) and 80.4% (78/97) of microorganisms were correctly identified to the genus and species levels, respectively. The saponin method identified 65.3% (32/49) of Gram-positive bacteria at the species level, whereas the Zybio Kit achieved a higher species-level identification rate of 79.6% (39/49) (p = 0.1153). The saponin method with additional on-plate formic acid extraction showed a significantly higher overall identification rate in comparison to the saponin method without that step for both genus (87.6% [85/97] vs. 70.1% [68/97], p = 0.0029) and species level (70.1% [68/97] vs. 46.4% [45/97], p = 0.0008). Identification rates of Gram-negative bacteria showed a higher identification rate, however, not statistically significant with additional Zybio Kit protocol step on both genus (85.4% [41/48] vs. 81.3% [39/48], p = 0.5858) and species level (77.1% [37/48] vs. 75% [36/48], p = 0.8120). Zybio Kit could offer an advantage in species-level identification, particularly for Gram-positive bacteria. The inclusion of on-plate formic acid extraction in the saponin method notably enhanced identification at both genus and species levels for Gram-positive bacteria. The extended protocol provided by the Zybio Kit could potentially offer an advantage in the identification of Gram-negative bacteria at both genus and species levels. Enhancements to the Zybio EXS2600 MALDI-TOF instrument software database are necessary.
我们评估了 Zybio EXS2600 基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）（Zybio Inc.，中国重庆）用于使用血培养阳性样本预处理试剂盒（Zybio Inc.，中国重庆）鉴定阳性血培养（BC）瓶中细菌的性能，与内部皂苷方法进行比较。在 BACTEC™ FX 系统发出阳性信号后，通过用于 MALDI-TOF MS 分析的亚培养生长生物量来确认鉴定。共分析了 94 个阳性 BC 瓶和 97 个细菌分离株。皂苷方法的属和种水平的总鉴定率分别为 89.7%（87/97）和 74.2%（72/97）。使用 Zybio 试剂盒，88.7%（86/97）和 80.4%（78/97）的微生物分别正确鉴定到属和种水平。皂苷方法在种水平上鉴定了 65.3%（32/49）的革兰氏阳性菌，而 Zybio 试剂盒的种水平鉴定率更高，为 79.6%（39/49）（p=0.1153）。与没有该步骤的皂苷方法相比，皂苷方法加平板甲酸提取在属（87.6%[85/97]与 70.1%[68/97]，p=0.0029）和种水平（70.1%[68/97]与 46.4%[45/97]，p=0.0008）的总鉴定率均显著更高。革兰氏阴性菌的鉴定率较高，但在属（85.4%[41/48]与 81.3%[39/48]，p=0.5858）和种水平（77.1%[37/48]与 75%[36/48]，p=0.8120）上均无统计学意义。Zybio 试剂盒在种水平鉴定方面具有优势，特别是对革兰氏阳性菌。在皂苷方法中加入平板甲酸提取显著提高了革兰氏阳性菌的属和种水平的鉴定率。Zybio 试剂盒提供的扩展方案可能在革兰氏阴性菌的属和种水平鉴定方面具有优势。需要对 Zybio EXS2600 MALDI-TOF 仪器软件数据库进行增强。
