Batista Sara, Fernández-Pittol Mariana, San Nicolás Lorena, Martínez Diego, Narváez Sofía, Espasa Mateu, Garcia Losilla Elena, Rubio Marc, Garrigo Montserrat, Tudó Griselda, González-Martin Julian
Unitat de Microbiologia, Departament de Fonaments Clínics, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, c/Casanova 143, 08036 Barcelona, Spain.
Fundació de Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques Augustí Pi i Sunyer (FRCB-IDIBAPS), 08036 Barcelona, Spain.
Antibiotics (Basel). 2025 Apr 4;14(4):381. doi: 10.3390/antibiotics14040381.
BACKGROUND/OBJECTIVES: Nontuberculous mycobacteria (NTM) infections are rising, particularly those by complex (MAC) and complex (MAB). Treating NTM infections is challenging due to their poor response to antibiotics. This study aimed to optimize the treatment of NTM infection by selecting antibiotics with bactericidal activity for combination therapy. To do this, we used the minimum bactericidal concentration (MBC) determination approach to define bactericidal or bacteriostatic activity. We developed three main objectives: validate a new method to determine MBC based on a reincubation method, determine MBC values of 229 NTM clinical isolates using the reincubation method, and evaluate antibiotic stability in preincubated microtiter plates.
First, we assessed the stability of the antibiotics included in SLOWMYCOI Sensititre™ microtiter plates. Five strains of MAC were studied comparing the minimum inhibitory concentrations (MICs) of those preincubated for seven days vs. non-incubated plates. Then, we evaluated the percentage of reproducibility of MBC values using two methods, reincubation and subculturing (standard or traditional method) in 30 MAC isolates. Finally, we validated the reincubation method and prospectively determined the MBC values of the 229 NTM clinical strains.
Antibiotic stability: The MIC was equivalent after 7 and 14 days for all the antibiotics, except rifampicin, for which the MIC increased by 2- to 3-fold after preincubation. Reincubation method: The percentage of reproducibility of the MBC values between the two methods was 95.2% (range 76.6% to 100%). Prospective validation: MBC/MIC ratios revealed differential bactericidal activity for most antibiotics according to the different species, being bactericidal in and , and predominantly bacteriostatic in MAB.
Preincubation of Sensititre™ microtiter plates did not alter the MIC values of the antibiotics included except for rifampicin, suggesting a loss of activity. MBC determination can be easily performed by the Reincubation method presented. MBC values provide useful additional information regarding MIC values since the MBC/MIC ratio reveals whether antibiotics have bactericidal or bacteriostatic activity according to the species, which is pivotal for selecting the most adequate antibiotic combination to ensure efficient treatment management.
背景/目的：非结核分枝杆菌（NTM）感染呈上升趋势，尤其是由鸟分枝杆菌复合群（MAC）和脓肿分枝杆菌复合群（MAB）引起的感染。由于NTM感染对抗生素反应不佳，治疗具有挑战性。本研究旨在通过选择具有杀菌活性的抗生素进行联合治疗来优化NTM感染的治疗。为此，我们使用最低杀菌浓度（MBC）测定方法来确定杀菌或抑菌活性。我们制定了三个主要目标：验证一种基于再培养法测定MBC的新方法，使用再培养法测定229株NTM临床分离株的MBC值，并评估预孵育微量滴定板中抗生素的稳定性。
首先，我们评估了SLOWMYCOI Sensititre™微量滴定板中所含抗生素的稳定性。研究了5株MAC菌株，比较了预孵育7天的平板与未孵育平板的最低抑菌浓度（MIC）。然后，我们使用两种方法，即再培养法和传代培养法（标准或传统方法），评估了30株MAC分离株中MBC值的可重复性百分比。最后，我们验证了再培养法，并前瞻性地测定了229株NTM临床菌株的MBC值。
抗生素稳定性：除利福平外，所有抗生素在7天和14天后的MIC相当，利福平预孵育后MIC增加了2至3倍。再培养法：两种方法之间MBC值的可重复性百分比为95.2%（范围为76.6%至100%）。前瞻性验证：MBC/MIC比值显示，根据不同菌种，大多数抗生素具有不同的杀菌活性，在MAC和堪萨斯分枝杆菌中具有杀菌作用，而在MAB中主要具有抑菌作用。
Sensititre™微量滴定板的预孵育除利福平外未改变所含抗生素的MIC值，提示活性丧失。所提出的再培养法可轻松进行MBC测定。MBC值提供了有关MIC值的有用附加信息，因为MBC/MIC比值揭示了抗生素根据菌种具有杀菌或抑菌活性，这对于选择最适当的抗生素组合以确保有效的治疗管理至关重要。
