Kidney infection is caused by bacteria which makes its way in to the urinary tract. E. coli and Enterococcus faecalis are the most common organisms which cause urinary infection. Coliforms and enterococci are the major reason for infections occurring from hospitals. Cystis and prostatitis are the precursor to Pyelonephritis . Usually the infection starts as cystis and prostatitis.
Other causes include defects in kidneys, urinary tract painful flow of urine due to kidney stones ,kidney stones, nephrostomy, pregnancy damaged bladder and in men prostate disease can lead to Pyelonephritis.Other major cause of the disease is Diabetes Mellitus. Patients suffering from Diabetes Mellitus suffer from frequent urination leading to the damage of the urinary bladder. Frequent urination damages the wall lining the urinary bladder leading to increased rate of infection. Change in sexual partner also leads to the infection of the urinary tract. This is high especially in females as multiple partners lead to the spread of infection from one person to another very quickly.
Usage of spermicides is also cited as one of the major reasons as this destroys the walls lining the fallopian tubules which weaken the tract leading to increased risk of infection. Genetics also contribute to this disease. Other causes include inadequate intake of fluids, irregular eating habits etc. In most cases of infection bacteria is the major cause of infection and other ailments of the kidney and the urinary tract only increases the rate of infection.