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Kidney infection

What is a Kidney infection

Kidney infection or pyelonephritis is a urinary tract infection that involves the upper urinary tract or the kidney. Kidney infections are caused by bacteria. Infections of the upper urinary tract or kidney are distinguished from a lower urinary tract infection or bladder+infection based on signs and symptoms.

Signs of a Kidney infection

Signs and symptoms of kidney infection include high fever, nausea and vomiting, low back pain, lethargy, and appearing ill. Infants may have poor feeding, irritability, and weight loss as the only symptoms. A bladder infection involves pain when urinating, the urge to urinate, urinating frequently, loss of bladder control (a trickle of urine coming out without being able to control it), pain below the belly button, and low-grade fever. There is a study that can be done to distinguish between a bladder infection and a kidney infection called DMSA renal scanning (dimercaptosuccinic acid). This study is performed in the radiology department of the hospital.

Kidney infection in Children

Children with a kidney infection who appear ill or who are vomiting should be admitted to the hospital and given intravenous fluids and antibiotics until the fever and vomiting have cleared. Children who are not vomiting and are not ill appearing may be treated with oral antibiotics for 14 days. In some cases, a dose or two of IM (intramuscular) antibiotics can be given in the physician’s office and the child may be sent home to complete the course with oral antibiotics. Urine samples are given prior to beginning antibiotics to look for specific bacteria and test for the sensitivity to antibiotics. Knowing the strain of bacteria is not enough. It is important to make sure that the particular bacteria will be sensitive to the antibiotic chosen. As with a bladder infection, all children who have had a kidney infection need to have the urinary tract evaluated for anatomic problems.

Urinary Tract Infection in Children

It is recommended that studies be done in children following a urinary tract infection based upon gender and age risk factors: with the first episode of urinary tract infection in all boys; in girls < 5 years old; and in older girls that have recurrent infections of the bladder or kidney. There are several studies that are done: ultrasound; voiding cystourethrography (VCUG); and nuclear cystography. The first test usually performed is the renal ultrasound which can be done as soon as possible after the urinary tract infection is diagnosed. The VCUG is done next, usually 2-6 weeks after infection, although the timing of this test is currently controversial. VCUG is necessary to make the diagnosis of vesicoureteral reflux (VUR). A dye is injected into the bladder through the urethra (via a catheter tube). The flow of the dye is then observed under fluoroscopy (best described as “real-time” video x-rays) by a radiologist. If the dye leaves the bladder and flows toward the kidney, then a diagnosis of VUR is made. There are 5 grades of VUR ranging from mild to severe. Nuclear cystography is similar to VCUG except that it uses less radiation, but is a little less precise. Nuclear cystography is used for yearly follow-up of VUR, or for screening of siblings of children with reflux.

Treatment of VUR in most cases is with low dose daily antibiotics, usually nitrofurantoin, amoxicillin or trimethoprim-sulfamethoxazole. Corrective surgery may be considered for grade V reflux and for those with recurrent urinary tract infections despite treatment with low dose daily antibiotics. Surgery involves re-implanting the ureter into the bladder wall at a different angle which allows the reflux-preventing valve effect during urination.

Prognosis for children with VUR is excellent. Most children with grade III or less will resolve by school age. Children are usually followed in the pediatrician’s office every 3 to 4 months to monitor the urine for infection. At yearly intervals, they should have follow-up studies using nuclear cystography. For grade IV or V reflux, consultation with a urologist should be made.

How will the urine sample be obtained?

This depends on the age of your child. In toilet trained children, a midstream urine is the usual manner of collection. Your child will clean himself with a special wipe then urinate a small amount in the toilet then collect the mid-portion of the urine stream in a cup. This is the same method used for adult. In infants and young toddlers there are 2 methods of collection–by a bag or by a catheter. The bags used are sterile and attach to the skin with an adhesive. The peri-urethral skin is first cleansed well and then the bag is applied. This is an acceptable method if the urine returns negative (without any bacteria). If there is bacteria present though it may be a contaminant from the surrounding skin and the test will need to be repeated, or a catheter used. For catheter collection, a small hollow tube is inserted through the urethral opening and inserted into the bladder to collect urine. This is a very sterile method of collecting urine. A method used in many offices and hospitals is a needle collection method where a needle is inserted just above the pubic bone into the bladder to collect the urine, called suprapubic aspiration. This is also considered a very sterile collection method.