An average person usually adopts an indifferent attitude towards kidney infection that is relatively uncommon in young age. But it can lead to kidney failure and with the infection spreading to the bloodstream it can be fatal in the elderly.
Primary reason behind a kidney getting infected is Gram negative bacteria that are found in the stool. From the stool, it sometimes comes up through the urethra and travels easily into the bladder and up to the kidneys.
Stones situated inside the "pelvis" can also be a cause of chronic infection in the kidney. These foreign bodies can allow bacteria to seed onto them. In this way kidney stones provide perfect breeding ground for bacteria, leading to recurrent infection.
Inflamed or enlarged prostate leads to a back up of urine from the bladder all the way up to the kidneys. In this reverse process the trap bacteria in the urinary tract can be trapped and dragged to kidney resulting in infection.
Blockage or narrowing of the urinary tract is also a cause for kidney infection. Children born with abnormal uterus develop infection in kidneys at a very early age. If a child gets frequent bladder, an X-Ray should be done to determine whether the child is born with an abnormally placed uterus. The blockage can be found and repaired before it spreads further only through X-Rays involving dye.
Pregnant women are much prone to infection in their kidneys. They often pass blood in the urine and complain unbearable pain on the side where the infected is. It can lead to irritability of the uterus and sometimes preterm delivery.
Obvious reason of kidneys getting infected is the bacteria coming up from the outside through the bladder. But there are instances when an individual got infection in the blood first, a condition called gram negative sepsis. Since kidneys filter blood, they can collect bacteria and thus develop infection in the kidneys themselves.
Often the symptoms and signs of kidney infection are unrecognizable especially in teenagers and young. An infected person may experience fever with flank pain on the side where the infection is. The patient also shows bacteria, blood and sometimes kidney cells in the urine analysis.
Kidney infection is a very painful infection hence should be treated aggressively. Every time you have fever doesn't mean that it is due to infection in kidney but there is no harm in consulting a registered medical practitioner.