It normally starts when a foreign substance, oftentimes bacteria, makes its way inside the leptomeninges, either by by direct contact or hematogenous spread through the blood brain barrier.

它通常由于异物，有时是细菌，进入柔脑膜；可能是通过直接接触或透过血脑屏障进行血性传播。

Usually, pyelonephritis from hematogenous spread is a consequence of septicemia or bacteremia - which is bacteria in the blood - as well as infective endocarditis, an infection of the inner layer of the heart.

通常情况下，通过血液传播的肾炎是由于败血症或菌血症（即细菌入血）或感染性心内膜炎（即心内膜受感染）。

The second way is hematogenous spread, which is when a pathogen enters the bloodstream and moves through the endothelial cells in the blood vessels making up the blood-brain barrier and gets into the CSF.

第二种方式是血性传播，这是当病原体进入血流并在构成血脑屏障的血管中跨越内皮细胞，从而进入脑脊液。