KIDNEY FOUNDATION FOR CHILDREN

      SAVING YOUNG LIVES

LABORATORY DIAGNOSIS OF UTI

1.  Routine urinalysis showing pyuria . > 5  WBCs /hpf in a centrifuged sample of urine

2. .Urine culture showing the growth of a single organism with 100,000 colonies /ml in a cleanly collected mid stream sample

WHEN TO SUSPECT UTI ?

UTI should be suspected in children with one or more of the following symptoms.

1  High fever without a focus

2. Fever with backache,abdominal or suprapubic  pain

3. Fever with vomiting

4 .Dysuria,frequency,new onset nocturnal enuresis

5 .Lethargy ,malaise ,poor feeding in infants

6. Any sick neonate

7. Any child with known urological problem who has fever


WHY IS UTI IMPORTANT ?

UTI is the third commonest infection in children.  Unlike acute gastroentiritis and pneumonias  UTI is not self evident. UTI in young children may be a marker of an underlying urological probllem. Febrile UTI can scar the kidney. Repeated UTIs increase the risk of scarring. Scarred kidneys can can lead to hypertension and even chronic renal falure .Scarring secondary to vesico-ureteric reflux and UTI is an important cause of end stage renal disease in older children and young adults

urinary tract infections

     DIAGNOSIS    AND TREATMENT OF THE

FIRST ATTACK

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SHOULD WE WAIT FOR THE CULTURE REPORT BEFORE TREATING UTI ?

No. Treatment should be started empirically based on clinical symptomatology and the presence of pyuria .Delay in instituting right therapy for more than 72 hours increases the risk of scarring.  However, urine culture should be always sent before giving the first dose of the antibiotic

WHEN CAN ORAL ANTIBIOTICS BE SAFELY GIVEN ?

Children who are not at risk for renal damage or general sepsis.

1. Older children above 5 years of age

2. Absent or low grade fever

3. Lower urinary tract symptomatology

4. Not toxic or vomiting

5. Children on parenteral therpay who have become afebrile and urine pus cells have disappeared can be chaged to oral treatment if sensitivity on culture permits.

 

WHICH CHILDREN WITH UTI SHOULD RECEIVE PARENTERAL ANTIBIOTICS?
Children at high risk for renal damage or generalized sepsis should receive parenteral antibiotics

1 .Neonates and young infants

2. Children with high fever,vomiting and toxic look.

3. Children with known or suspected urological anomaly

4. Children with elevated creatinine.


COMMON ERRORS MADE IN THE DIAGNOSIS OF UTI


CHOICE OF ANTIBIOTICS

Parenteral  - Third generation cephalosporins IV

Oral            - According to known local prevalence

                    Current first line choice is usually cefixime

Duration of therapy is 10 days

MISINTERPRETATION OF PYURIA


UTI will invariably have pyuria but all pyuria is not due to UTI

.Several other causes of pyuria exist and should be considered especially when pyuria is mild,when the child is asymptomatic and urine culture is negative.


CAUSES OF PYURIA

  • 1.UTI
  • 2.Hypercalciuria
  • 3.Stones
  • 4.Thread worm infestation
  • 5 Balanoposthitis
  • 6.Vulval infections
  • 7.Drug induced interstitial nephritis
  • 8.Glomerulonephritis


HOW TO COLLECT THE RIGHT SAMPLE FOR URINE CULTURE


  • Sample should be collected  before  administration  of first dose of antibiotics
  • .Clean genitals with water.Do not use soap or antiseptics.
  •  .In boys retract the prepuce and clean the glans.Do not use force; In girls separate the labia majora and minora and clean with water.
  •  When the child passes urine allow the first few ml to flow out.Then collect mid stream sample directly in culture bottle
  • .Cap the culture bottle and store in ice pack and send to the laboratory



ERRORS IN URINE CULTURE

Urine culture positive with significant colony count is necessary to make a definitive diagnosis of UTI .However both false positive,false negative cultures are fairly common and occur due to errors in collecting the sample.


CAUSES OF FALSE NEGATIVE CULTURE

  • Cleaning of genitals with antiseptics or soap before collection
  • .Collecting for culture after antibioitc is given.Even one dose will inhibit bacterial growth
  • ..Infections other than bacteria- fungal or TB infection


CAUSES OF FALSE POSITIVE CULTURE


  • .Collection without cleaning genitals
  • .Local infections
  • .Keeping the culture bottle open for  a long time before collection
  • .Collection from urinary bag,mackintosh or a pan.
  • .Collecting in a non-sterile bottle and then transferring to culture bottle.
  • .Delay of more than one hour in transport

Contaminated cultures may have mixed organisms,common skin commensals and may have growth < 100,000/ml..

WHAT SHOULD BE DONE FOR CHILDREN WITH SUSPECTED RENAL ANOMALY ?

1. The child should receive urinary prophylaxis after completion of the antibiotic course .Urinary prophylaxis should be continued till imaging studies re complete and further decisions can be taken.


2. USG kidneys,ureters and bladder in all cases


3.MCU  after the infection is clear in selected children


  a. children below 1 year of age 

  b. in older children with abnormal USG findings.

  c .Children with recurrent UTI


4. DMSA scan after 4 to 6 months of the infection

WHEN TO SUSPECT AN UNDERLYING RENAL ANOMALY ?

1. Febrile UTI in a child below 1 year of age

2. Children with abnormalities on antenatal ultrasound

3 .Children especially boys with voiding complaints-poor stream of urine,interrupted stream of urine,dribbling,

4. Children with neurological problems  myelomeningocoele,          anorectal malformations

5.Children with recurrent UTI

6.Children with raised serum creatinine or hypertension or failure to thrive.

  • Making a diagnosis of UTI in the absence of symptoms
  • Equating pyuria with UTI
  • False positive or false negative urine cultures due to improper collection


ASYMPTOMATIC BACTERIURIA


  • Significant bacteruria in the absence of symptoms is NOT UTI
  • It is asymptomatic bacteruria
  • Asymptomatic Bacteruria should NOT be treated with antibiotics

 when should  a pediatric nephrologist BE CONSULTED ?

  •    In children with antenatally detected anomalies
  • .  In children with  VUR grade 3 ,4 or 5.
  •   .In children with scars on DMSA
  • . Children with recurrent UTI
  •  .Children with hypertension or creatinine
  • . Prior to surgery
  •   Prior to repeat MCU


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