Kidney inflammation. Gross clinical specimen of a sectioned kidney in interstitial nephritis. Healthy tissue (dark red) contrasts with a large area of damaged tissue (pale brown) across centre. Nephritis refers to kidney inflammation, while the term interstitial means that the inflammation is of kidney tissue other than the glomerulus tubes (the filtrating structures of a kidney). It may be caused by a bacterial infection or a reaction to a drug or toxic material. Cessation of exposure to the offending drug or toxin is normally sufficient for recovery, though steroid drug therapy may also be required. Renal failure will require dialysis and a kidney transplant.