Upper Urinary Tract Infections (Upper UTIs)

Clinical features, Diagnosis, Management, Prognosis,

In about 50% of cases of lower urinary tract infections the kidney is involved as well.

Bacterial infection of the renal parenchyma is usually due to ascent of organisms through the ureter, although in a few cases it is blood borne. About 75% of infections are due to E. coli, the remainder to proteus and klebsiella species, staphylococci or streptococci. 

Commonly one or more complicating factors are present, but in adult women and infants infection, possibly due to a virulent organism, may occur in the absence of such factors.

Stasis within the tract compromises its defence and renal cysts or scars due to previous inflammation facilitate establishment of bacteria because they obstruct groups of nephrons and impair drainage of urine. Very few organisms are required to infect the medulla and once established there, their eradication is difficult because low blood flow, high osmolarity and high concentration of H⁺ and ammonia interfere with accumulation of leukocytes and phagocytosis.

1. Acute Pyelonephritis 

In this condition the renal pelvis (pyelon) is acutely infected/inflamed together with the focuses of inflammation in the renal parenchyma (microabscesses) and associated cystitis.

2. Chronic Pyelonephritis 

In the absence of urinary tract abnormalities acute pyelonephritis rarely leads to serious chronic renal disease. Possibly the most important predisposing factor for chronic infection is the presence of severe vesico-ureteric reflux in children which is commonly congenital. In this way microorganisms from the bladder may then reach the kidney every time during the micturition, and cause frequent episodes of bacterial infection in the kidney. Kidney stones may also predispose from chronic pyelonephritis. The fully developed case usually shows gross scarring of the kidneys, which may be much reduced in size with narrowing of the cortex and medulla.

Clinical features:  < BACK TO TOP >

1. Acute Pyelonephritis

       Typically there is sudden onset of pain in one or both loins, and it radiates to the inguinal and suprapubic area.

       Many patients have dysuria and frequent passage of small amounts of cloudy urine due to cystitis (bacteria are constantly delivered from the kidney into the bladder).

       Temperature of 38-40 ^oC with general manifestations of fever (chills, muscle aches, malaise, anorexia) is present, sometimes there is also nausea and vomiting.

       In children the disease often presents as fever sometimes with vomiting and diarrhoea but without localising symptoms (in a febrile child the urine should always be analysed to rule out a UTI).

       Acute pyelonephritis must be differentiated from other intra-abdominal conditions that may present in a similar fashion, such as appendicitis, urolithiasis, in women ectopic pregnancy and ruptured ovarian cyst.

2. Chronic Pyelonephritis

       In contrast to acute pyelonephritis in many cases of chronic pyelonephritis no symptoms arise directly from the renal lesions; fever and pain are intermittent and often vague and inconsistent.

       Sometimes frequency of micturition and dysuria are present, which reflect the involvement of the lower urinary tract.

       Patients usually complain of general symptoms like fatigue and vague ill-health.

       Eventually secondary hypertension and renal failure develop in advanced stage (no earlier than 20 years after the onset).

Diagnosis:  < BACK TO TOP >

1. Acute Pyelonephritis

       Clinical picture and physical examination are very suggestive; tenderness and guarding in the lumbar region are usually noted on palpation and percussion (so-called ‘punch tenderness?.

       Urine analysis reveals mild proteinuria and haematuria, while microscopic examination of urine sediment shows numerous leukocytes, white blood cell casts and bacteria, some red cells and epithelial cells.

       Urine culture for bacterial count and identification is carried out, usually susceptibility of isolated bacteria to antibiotics (so called antibiogram) is determined.

       Characteristically there is leukocytosis and raised ESR (markers of inflammation).  

2. Chronic Pyelonephritis

       Clinical picture is notoriously unreliable, and this condition can escape diagnosis for many years.

       The IVU shows the diagnostic features (the kidneys are reduced in size and there is localised contraction of the renal tissue associated with clubbing-dilation of the adjacent calyces).

       Culture of the urine is mandatory (E.coli is the most common organism), urine analysis and microscopic examination of urine sediment are routinely carried out, when interpretation is similar to acute pyelonephritis.

       Other tests may be performed to identify any abnormality causing obstruction to the flow of urine (ultrasound, CT).

       A micturating cystoureterogram will disclose the vesicoureteric reflux.

       Renal function should be assessed by estimation of the blood urea and creatinine, and creatinine clearance.

Management of acute and chronic pyelonephritis:  < BACK TO TOP >

       Both acute and chronic pyelonephritis require antibiotic treatment, preferably targeting identified causative organism.

       Initially, while waiting for antibiogram results, trimethoprim, co-trimoxazole, ampicillin [Penbritin, Ampicyn, Alphacin], amoxycillin [Amoxil, Cilamox, Moxacin, Alphamox] or fluoroquinolones can be used because all are active against E.coli.

       In more severe or septicaemic cases intravenous therapy using ampicillin, amoxycillin, an aminoglycoside antibiotic [Gentamycin] or a cephalosporin such as cefotaxime [Claforan], ceftriaxone [Rocephin] and cefepime [Maxipime] should be used.

       Urine culture should be repeated later and treatment adjusted if necessary.

       Any abnormality of the urinary tract should, if possible, be corrected; vesico-ureteric reflux in children frequently spontaneously disappears in few years, alternatively a reconstructive surgery can be carried out.

       In advanced chronic pyelonephritis with renal failure the patient will need treatment described later in section about chronic renal failure.

Prognosis  < BACK TO TOP >

• - - 

(source : Dr Zoran Pletikosa)