克雷伯氏菌属（Klebsiella）是革兰氏阴性菌，杆状，其中包括了人类感染症常见的克雷伯氏肺炎菌(Klebsiella pneumoniae)。克雷伯氏菌属的命名，是纪念德国微生物学家Edwin Klebs，他首先在1887年描述了克雷伯氏肺炎菌。

克雷伯氏菌在自然环境中普遍存在。克雷伯氏菌通常都有大量的黏性的多糖形成的荚膜包覆。它们可以在人类，特别是免疫力低弱的个体造成肺炎，尿路感染，菌血症等等感染症。

克雷伯氏菌属包含12个种，其中，克雷伯氏肺炎菌(Klebsiella pneumoniae)、Klebsiella oxytoca及Klebsiella rhinoscleromatis这三种都曾在人类临床样本中被检出。临床上，克雷伯氏肺炎菌是此菌属中最重要的致病菌。

Klebsiella is a genus of nonmotile, Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule. It is named after the German microbiologist Edwin Klebs (1834–1913).

Klebsiella species are found everywhere in nature. This is thought to be due to distinct sublineages developing specific niche adaptations, with associated biochemical adaptations which make them better suited to a particular environment. They can be found in water, soil, plants, insects, animals, and humans.