Comparison of Zybio Kit and saponin in-house method in rapid identification of bacteria from positive blood cultures by EXS2600 matrix-assisted laser desorption ionization time-of-flight mass spectrometry system.

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.

Peras M ，Mareković I ，Kuliš T ，Markanović M ，Budimir A ... -  《-》

Applicability of an in-house saponin-based extraction method in Bruker Biotyper matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system for identifying bacterial and fungal species in positively flagged pediatric VersaTREK bloo

Early identification of pathogens causing bloodstream infection (BSI) is critical for prompt administration of appropriate antimicrobial therapy. We used an in-house saponin-based extraction method to evaluate the performance of Bruker Biotyper MALDI-TOF MS system (MALDI Biotyper) for bacterial and fungal identification in 2013 positively-flagged VersaTREK blood culture bottles. A total of 180 monomicrobial and 23 polymicrobial positive blood cultures were investigated. Among monomicrobial positive blood cultures, the MALDI Biotyper recognized 90.6% and 81.7% of organisms directly from the flagged blood culture bottles to the genus and species levels, respectively. The MALDI Biotyper also correctly characterized one of the polymicrobial organisms to the species level in 20 (87%) bottles and to the genus level in 21 (91.3%) bottles. The overall identification rate using our protocol was 90.6% (184/203) and 82.3% (167/203) for genus and species levels, respectively. Identification accuracy was higher for Gram-positive than Gram-negative organisms and was the lowest for yeasts. Score values of identification were ≥1.500 for 200 (98.5%) bottles, ≥1.700 for 195 (96.1%) bottles and ≥2.000 for 182 (89.7%) bottles. Moreover, 83.5% and 92% of the isolates were identified precisely to species and genus level with the lower cutoff score of 1.500. Using our protocol also helped identifying BSI pathogens 18-24 h earlier compared to the sub-cultured colonies. Using Bruker MALDI Biotyper for identification of isolates directly from positive VersaTREK blood culture bottles, our in-house saponin-based protocol provided a more rapid turn-around time for correct identification of BSI pathogens than the conventional methods.

Hu YL ，Hsueh SC ，Ding GS ，Chuang PC ，Chen JM ，Lu CY ，Chang LY ，Huang LM ，Lee PI ，Hsueh PR ... -  《-》

Rapid identification of microorganisms from positive blood cultures in pediatric patients by MALDI-TOF MS: Sepsityper kit versus short-term subculture.

The rapid diagnosis of bloodstream infection (BSI) often leads to better clinical outcomes. The present study was conducted to compare two rapid protocols (Sepsityper kit and short-term subculture) for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based identification of microorganisms from positive blood cultures in pediatric patients. This study was conducted between May 1, 2018, and April 30, 2019, at a tertiary children's hospital in eastern China. Only monomicrobial blood cultures included in this study were used to conduct the Sepsityper kit protocol and short-term subculture protocol at the same time. In total, 115 monomicrobial blood cultures were included in this study. For the Sepsityper kit protocol, 85.2% and 64.3% of microorganisms were correctly identified to the genus (score ≥ 1.700) and species levels (score ≥ 2.000), respectively. For the short-term subculture protocol, 89.6% and 70.4% of microorganisms were correctly identified to the genus and species levels, respectively. At the genus level (P = .321) or the species level (P = .325), there was no significant difference between the Sepsityper kit protocol and the short-term subculture protocol. Moreover, the short-term subculture protocol exhibited similar performance between Gram-positive bacteria (GPB) and Gram-negative bacteria (GNB) (the genus level: 93.7% (GPB) versus 87.9% (GNB), P = .518; the species level: 68.4% (GPB) versus 81.8% (GNB), P = .147). In addition, the Sepsityper kit protocol exhibited similar performance between GPB and GNB at the genus level (86.1% (GPB) versus 84.8% (GNB), P = 1.000). However, the Sepsityper kit protocol exhibited better performance in GNB at the species level (58.2% (GPB) versus 81.8% (GNB), P = .017). The rates of yeast-like fungi were correctly identified to the genus level (0.0%) or the species level (0.0%) for short-term subculture protocol were significantly lower than those of other microorganisms (the genus level: 92.0%, P = .001; the species level: 72.3%, P = .024). However, a similar result of identification was not found using the Sepsityper kit protocol (the genus level: P = .384; the species level: P = .599). In addition, the two rapid protocols both exhibited better performance at the genus level when the time to positivity (TTP) of blood cultures <19 h (the Sepsityper kit protocol: 91.8% (TTP < 19 h) versus 77.8% (TTP ≥ 19 h), P = .034; the short-term subculture protocol: 95.1% (TTP < 19 h) versus 83.3% (TTP ≥ 19 h), P = .040). In addition, the two rapid protocols both exhibited better performance at the species level when the TTP of blood cultures was <19 h (the Sepsityper kit protocol: 78.7% (TTP < 19 h) versus 48.1% (TTP ≥ 19 h), P = .000; the short-term subculture protocol: 83.6% (TTP < 19 h) versus 55.6% (TTP ≥ 19 h), P = .001). The Sepsityper kit protocol and short-term subculture protocol are both reliable and rapid methods for the identification of most microorganisms from positive blood cultures in pediatric patients. The performance of these two rapid protocols is associated with the TTP of blood cultures.

Fang C ，Zhou Z ，Li J ，Chen X ，Zhou M ... -  《-》

Direct identification of bacteria from BacT/ALERT anaerobic positive blood cultures by MALDI-TOF MS: MALDI Sepsityper kit versus an in-house saponin method for bacterial extraction.

Meex C ，Neuville F ，Descy J ，Huynen P ，Hayette MP ，De Mol P ，Melin P ... -  《-》

Formic acid sandwich method is well-suited for filamentous fungi identification and improves turn around time using Zybio EXS2600 mass spectrometry.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is extensively employed for the identification of filamentous fungi on MALDI Biotyper (Bruker Daltonics) and Vitek MS (biomerieux), but the performance of fungi identification on new EXS2600 (Zybio) is still unknow. Our study aims to evaluate the new EXS2600 system's (Zybio) ability to rapidly identify filamentous fungi and determine its effect on turnaround time (TAT) in our laboratory. We tested 117 filamentous fungi using two pretreatment methods: the formic acid sandwich (FA-sandwich) and a commercial mold extraction kit (MEK, Zybio). All isolates were confirmed via sequence analysis. Laboratory data were extracted from our laboratory information system over two 9-month periods: pre-EXS (April to December 2022) and post-EXS (April to December 2023), respectively. The total correct identification (at the species, genus, or complex/group level) rate of fungi was high, FA-sandwich (95.73%, 112/117), followed by MEK (94.02%, 110/117). Excluding 6 isolates not in the database, species-level identification accuracy was 92.79% (103/111) for FA-sandwich and 91.89% (102/111) for MEK; genus-level accuracy was 97.29% (108/111) and 96.39% (107/111), respectively. Both methods attained a 100% correct identification rate for Aspergillus, Lichtheimia, Rhizopus Mucor and Talaromyces species, and were able to differentiate between Fusarium verticillioides and Fusarium proliferatum within the Fusarium fujikuroi species complex. Notably, high confidence was observed in the species-level identification of uncommon fungi such as Trichothecium roseum and Geotrichum candidum. The TAT for all positive cultures decreased from pre EXS2600 to post (108.379 VS 102.438, P < 0.05), and the TAT for tissue decreased most (451.538 VS 222.304, P < 0.001). The FA-sandwich method is more efficient and accurate for identifying filamentous fungi with EXS2600 than the MEK. Our study firstly evaluated the performance of fungi identification on EXS2600 and showed it is suitable for clinical microbiology laboratories use.

Wu C ，Ao K ，Zheng Y ，Jin Y ，Liu Y ，Chen Z ，Li D ... -  《BMC MICROBIOLOGY》