PPGCM - Programa de Pós-Graduação em Ciências Médicas, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
LABRESIS - Laboratório de Pesquisa em Resistência Bacteriana, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos, Porto Alegre, RS, 2350, Brazil.
Braz J Microbiol. 2023 Sep;54(3):1841-1846. doi: 10.1007/s42770-023-01014-1. Epub 2023 Jul 4.
Polymyxin B resistance is an emerging problem worldwide. The reference method to determine susceptibility to polymyxins is broth microdilution (BMD). As BMD is time consuming, it is necessary to develop new methodologies to provide faster evaluation of polymyxin susceptibility. This study aimed to evaluate polymyxin B susceptibility of Enterobacterales using an adapted methodology of relative growth (RG) by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). A total of 60 isolates of Enterobacterales (22 resistant and 38 susceptible to polymyxin B by BMD) were evaluated. The adapted RG technique presented categorical agreement of 96.7% with only 2 major errors (3.3%) in comparison to BMD. Our findings demonstrate a high agreement between BMD and adapted RG, indicating that this methodology is promising for differentiating polymyxin B-susceptible isolates from polymyxin B-resistant isolates and could be implemented routinely in microbiology laboratories that already use the MALDI-TOF MS to identify bacteria.
多黏菌素 B 耐药性是一个全球性的新问题。测定多黏菌素敏感性的参考方法是肉汤微量稀释法（BMD）。由于 BMD 耗时较长，因此有必要开发新的方法学来更快地评估多黏菌素的敏感性。本研究旨在使用基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）的相对生长（RG）的改良方法来评估肠杆菌科对多黏菌素 B 的敏感性。共评估了 60 株肠杆菌科（22 株对 BMD 耐药，38 株对多黏菌素 B 敏感）。与 BMD 相比，改良 RG 技术的分类一致性为 96.7%，仅出现 2 次主要错误（3.3%）。我们的研究结果表明 BMD 和改良 RG 之间具有高度一致性，表明该方法在区分多黏菌素 B 敏感株和多黏菌素 B 耐药株方面具有很大的潜力，并且可以在已经使用 MALDI-TOF MS 来鉴定细菌的微生物学实验室中常规实施。
