病原细菌（英语：Pathogenic bacteria）是指能导致细菌传染病的细菌。本条目主要针对会造成人类传染病的病原细菌。

大部份的细菌是无害，甚至是有益的，不过有些细菌是病原体。像结核就是疾病总量最高的细菌性疾病之一，是由结核杆菌所传染，每年死亡人数约二百万人，大部份位于撒哈拉以南非洲。许多重要的疾病也是由病原细菌造成的，像肺炎就是由链球菌属及假单胞菌造成，而食物中毒可能是由志贺氏菌属及沙门氏菌属引起。像破伤风、伤寒、白喉、梅毒及麻风病都是由病原细菌引起的疾病。病原细菌也是开发中国家高婴儿死亡率的原因之一。

Pathogenic bacteria are bacteria that can cause infection. This article deals with human pathogenic bacteria.

Although most bacteria are harmless or often beneficial, several are pathogenic. One of the bacterial diseases with the highest disease burden is tuberculosis, caused by the bacterium Mycobacterium tuberculosis, which kills about 2 million people a year, mostly in sub-Saharan Africa. Pathogenic bacteria contribute to other globally important diseases, such as pneumonia, which can be caused by bacteria such as Streptococcus and Pseudomonas, and foodborne illnesses, which can be caused by bacteria such as Shigella, Campylobacter, and Salmonella. Pathogenic bacteria also cause infections such as tetanus, typhoid fever, diphtheria, syphilis, and leprosy. Pathogenic bacteria are also the cause of high infant mortality rates in developing countries.