Most cases of pyelonephritis start acutely, with patients abruptly experiencing bacterial infections in their urinary system, causing inflammation in areas such as the renal pelvis and calyces. This manifests clinically with symptoms such as fever and back pain. This acute onset type is called acute pyelonephritis, and it is relatively easy to treat because it involves a bacterial infection that requires antibacterial treatment. Hence, it is generally manageable. However, if a patient's condition becomes prolonged and turns into chronic pyelonephritis, treatment may be more challenging. The bacteria causing chronic pyelonephritis are often drug-resistant, and this condition might be associated with predisposing factors for urinary infections, such as urinary system stones, anatomical abnormalities of the urinary tract, or obstructions that can conceal bacteria or contribute to their resistance, making treatment more difficult.