Antibiotic combination therapies are important for the efficient treatment of many types of infections, including those caused by antibiotic-resistant pathogens. Combination treatment strategies are typically used under the assumption that synergies are conserved across species and strains, even though recent results show that the combined treatment effect is determined by specific drug–strain interactions that can vary extensively and unpredictably, both between and within bacterial species. To address this problem, we present a new method in which antibiotic synergy is rapidly quantified on a case-by-case basis, allowing for improved combination therapy. The novel CombiANT methodology consists of a 3D-printed agar plate insert that produces defined diffusion landscapes of 3 antibiotics, permitting synergy quantification between all 3 antibiotic pairs with a single test. Automated image analysis yields fractional inhibitory concentration indices (FICis) with high accuracy and precision. A technical validation with 3 major pathogens, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, showed equivalent performance to checkerboard methodology, with the advantage of strongly reduced assay complexity and costs for CombiANT. A synergy screening of 10 antibiotic combinations for 12 E. coli urinary tract infection (UTI) clinical isolates illustrates the need for refined combination treatment strategies. For example, combinations of trimethoprim (TMP) + nitrofurantoin (NIT) and TMP + mecillinam (MEC) showed synergy, but only for certain individual isolates, whereas MEC + NIT combinations showed antagonistic interactions across all tested strains. These data suggest that the CombiANT methodology could allow personalized clinical synergy testing and large-scale screening. We anticipate that CombiANT will greatly facilitate clinical and basic research of antibiotic synergy.

抗生素联合疗法对于有效治疗多种类型的感染（包括那些由抗生素耐药性病原体引起的感染）非常重要。尽管最近的结果表明，联合治疗的效果是由特定的药物-菌株相互作用决定的，而这种相互作用在细菌物种之间和内部可能会发生广泛而无法预测的变化，但通常在假设物种和菌株之间具有协同作用的前提下使用联合治疗策略。为了解决这个问题，我们提出了一种新的方法，其中可以根据具体情况快速量化抗生素协同作用，从而改善组合疗法。新颖的CombiANT方法包括3D打印的琼脂平板插入物，可产生3种抗生素的明确扩散图景，一次测试即可定量所有3对抗生素之间的协同作用。自动化图像分析可产生高精度和高精度的分数抑制浓度指数（FICis）。对3种主要病原体进行了技术验证，大肠杆菌，铜绿假单胞菌和金黄色葡萄球菌表现出与棋盘方法相当的性能，其优点是大大降低了CombiANT的测定复杂性和成本。协同筛选12种E的10种抗生素组合。大肠杆菌尿路感染（UTI）临床分离株说明了对精细联合治疗策略的需求。例如，甲氧苄啶（TMP）+硝基呋喃妥因（NIT）和TMP +美西林（MEC）的组合显示出协同作用，但仅对于某些分离株而言，而MEC + NIT的组合则在所有测试菌株中均表现出拮抗作用。这些数据表明，CombiANT方法可以进行个性化的临床协同测试和大规模筛选。我们预计CombiANT将大大促进抗生素协同作用的临床和基础研究。