Hi doctors, was just wondering what is a kidney infection and what are the symptoms?

Kidney infection: Pyelonephritis. An inflammatory response of kidney due to a bacterial infection. Most common route 4 bacteria to gain access to kidney is via urinary tract. Bacteria enter via urethra ; then travel up ureters from bladder to kidney. Less commonly via blood stream from skin or gum infection. Symptoms: flank or abdominal pain, fever, chills, blood in urine, burning on urination, lower ribs tender.