Which of the following conditions is characterized by chronic, bacterial plaques?

Malacoplakia is characterized by the presence of chronic, bacterial plaques, typically arising from a defective immune response to a bacterial infection. This condition is marked by the accumulation of macrophages that have failed to properly digest bacteria, leading to the formation of characteristic yellowish plaques—hence the name "malacoplakia," which means "soft plaques" in Greek.

In malacoplakia, the bacterial plaques are often associated with the presence of urinary tract infections, particularly with organisms such as Escherichia coli. The plaques can be found predominantly in the bladder but can also occur in other tissues. Histologically, you would observe large foamy macrophages (von Hansemann cells) and Michaelis-Gutmann bodies, which are indicative of the condition.

Other conditions listed, such as cystitis and ureteritis cystica, reflect different pathological processes and do not specifically involve the formation of chronic bacterial plaques. Interstitial cystitis is a complex syndrome that may not be directly associated with bacterial infections at all, as it primarily involves inflammation of the bladder wall without clear infectious etiology. Thus, malacoplakia is distinct in its hallmark feature of chronic bacterial plaques.