The sum of all of the interactions between single bacteria and host cells determines if an infection is cleared, controlled, or progresses at the whole host-organism level. These individual interactions have independent trajectories defined by diverse and dynamic host-cell and bacterial responses. Focusing on Mycobacterium tuberculosis infection, we discuss how advances in single-cell technologies allow investigation of heterogeneity in host-pathogen interactions and how different layers of heterogeneity in the host affect disease outcome. At late stages of infection, many single interactions co-exist and different outcomes depend on inter-granuloma and intra-granuloma heterogeneity. However, during bottleneck events involving small numbers of bacteria, random events, such as chance interactions with more or less permissive host cells, play a decisive role and may explain why some exposed individuals never develop the disease.

单个细菌和宿主细胞之间所有相互作用的总和决定了感染是否在整个宿主生物体水平上被清除、控制或进展。这些单独的相互作用具有由多样化和动态的宿主细胞和细菌反应定义的独立轨迹。专注于结核分枝杆菌感染，我们讨论了单细胞技术的进步如何允许研究宿主 - 病原体相互作用的异质性以及宿主中不同层次的异质性如何影响疾病结果。在感染的晚期阶段，许多单一的相互作用共存，不同的结果取决于肉芽肿间和肉芽肿内的异质性。然而，在涉及少量细菌的瓶颈事件中，随机事件（例如与或多或少允许的宿主细胞的偶然相互作用）起着决定性作用，并且可以解释为什么一些暴露的个体从未患上这种疾病。