Vecchione Alessandra, Florio Walter, Celandroni Francesco, Barnini Simona, Lupetti Antonella, Ghelardi Emilia
Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy.
Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy.
Front Microbiol. 2018 Oct 15;9:2400. doi: 10.3389/fmicb.2018.02400. eCollection 2018.
The development of rapid diagnostic assays for the identification and analysis of antimicrobial resistance of fungal pathogens causing invasive mycoses is of utmost importance to reduce morbidity and mortality. We evaluated the performance of a novel rapid procedure directly applied to monomicrobial blood cultures from patients with bloodstream infection caused by yeast species, including nine and three non- species. For the rapid procedure herein developed, samples of positive blood cultures were transferred into serum separator tubes and treated with sodium dodecyl sulfate; the yeast layer was recovered and directly used for microbial identification by MALDI-TOF mass spectrometry and antifungal susceptibility testing (AFST) by the Sensititre YeastOne Y010 panel. The results were compared with those obtained by the same methods applied to colonies isolated on solid media. Using a score value of 1.700 as cut-off for valid identification, the rapid procedure identified 66 of 124 (53.2%) isolates, all of which concordantly with the reference method. However, adopting a cut-off ≥1.300 and ≥4 consecutive repetitions of the same species in the list of matches would extend concordant identification to 107/124 (86.3%) samples. Importantly, AFST revealed essential agreement between the two methods for all the isolate/antifungal drug combinations tested, including misidentified and not identified isolates. Therefore, the procedure herein developed represents a valid alternative for AFST of yeasts from positive blood cultures, yielding accurate and reliable results at least 24 h earlier than with the routine procedure, thus allowing clinicians to promptly streamline antifungal therapy.
开发用于鉴定和分析引起侵袭性真菌病的真菌病原体耐药性的快速诊断检测方法对于降低发病率和死亡率至关重要。我们评估了一种新型快速检测方法的性能，该方法直接应用于由酵母菌种引起血流感染患者的单一微生物血培养物，包括9种和3种非菌种。对于本文开发的快速检测方法，将阳性血培养物样本转移至血清分离管中，并用十二烷基硫酸钠处理；回收酵母层，直接用于通过基质辅助激光解吸电离飞行时间质谱进行微生物鉴定以及通过Sensititre YeastOne Y010检测板进行抗真菌药敏试验（AFST）。将结果与应用于在固体培养基上分离的菌落的相同方法所获得的结果进行比较。使用1.700的评分值作为有效鉴定的临界值，快速检测方法鉴定出124株分离株中的66株（53.2%），所有这些结果均与参考方法一致。然而，采用≥1.300的临界值以及在匹配列表中同一菌种连续重复≥4次，可使一致鉴定扩展至107/124（86.3%）个样本。重要的是，AFST显示，对于所有测试的分离株/抗真菌药物组合，包括误鉴定和未鉴定的分离株，两种方法之间基本一致。因此，本文开发的检测方法是对阳性血培养物中酵母进行AFST的有效替代方法，比常规方法至少提前24小时产生准确可靠的结果，从而使临床医生能够迅速简化抗真菌治疗。
