Your urinary tract is your body’s drainage system that filters your blood through your kidneys. They are the two bean shaped organs, each located near the lower back region of the body. Kidneys help by doing various functions and apart from removing waste from our body they also help in maintaining overall fluid balance; regulating and filtering minerals from blood; filtering waste materials from food, medications, and toxic substances; and creating hormones that help produce red blood cells, promote bone health, and regulate blood pressure. Your renal veins go inside your kidney, and bring in the blood to a system called “the loop of henle,” located in your nephrons, which filters out the blood. The kidney filters about 200 quarts of blood per day. Filtered blood comes out to continue to circulate back to the heart while the waste like urea continues to pass through the ureter and accumulate in your bladder as urine until released. 

Sometimes, bacteria may accumulate or travel back up your urinary system causing urinary tract infections (UTI), which both sexes can obtain. Symptoms include pain in the pelvis or groin area or pain during urination. During urination, you may observe more frequent urination, cloudy urine, blood in urine or irritable sensations. When the bacteria travels up to your kidney or you have bacteria in your bloodstream, it can cause a kidney infection. The official term for kidney infections is Pyelonephritis. In the case of a kidney infection, you may get a fever; chills; a definite flank pain on the left, right or both sides of your kidney located on either side of your back around your waist and under your ribs area; nausea; and vomiting, in addition to similar symptoms of a UTI.

Urinary tract infections are more common in females due to the shorter urethra in women making it easier for bacteria to travel. Pregnant women have a higher risk of infection and may cause urinary blockage. Infections are always prone to causing damage to nerves so sometimes you may not even feel the sensations related to a bladder infection. If left untreated, it can cause kidney scarring leading to chronic kidney disease or a type of blood poisoning called Septicemia. If you are having such symptoms, it is crucial to see a doctor right away. To confirm a kidney infection, a urine sample is taken at the doctor's office to test the bacteria, blood or pus in your urine. A blood sample is more accurate in determining bacteria or other infectious organisms in your blood. Other tests might include an ultrasound, CT scan or a type of X-ray called a voiding cystourethrogram. 

A kidney infection requires prompt medical attention because if not treated properly, it can permanently damage your kidneys or the bacteria can spread to your bloodstream. Kidney infection treatment, which usually includes antibiotics, might require hospitalization. Though it depends on the type of bacteria and infection, but usually upon starting antibiotics, within a couple of days your symptoms will improve. It is always advised to complete the full course of antibiotics. Your doctor during a follow up may also ask for a repeat urine test to confirm that the infection is cleared.

References:

https://www.healthline.com/health/human-body-maps/kidney

https://www.thoughtco.com/kidneys-anatomy-373243

https://www.urologyhealth.org/urology-a-z/k/kidney-(renal)-infection-pyelonephritis

https://www.mayoclinic.org/diseases-conditions/kidney-infection/symptoms-causes/syc-20353387