THE INVESTIGATION OF URINARY TRACT INFECTIONS (UTI) |
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Definition |
The term urinary tract infection encompasses a broad spectrum of infectious processes involving the urinary tract. |
Initial laboratory investigations |
Pretreatment midstream urine (MSU) for MCS |
CONDITION |
SPECIFIC LABORATORY TESTS |
Acute uncomplicated cystitis in women |
Pretreatment midstream urine (MSU) for MCS |
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Those most at risk are sexually active women. Most UTIs in this population are uncomplicated and are rarely associated with functional or anatomic abnormalities. Aggressive diagnostic work-ups in young women presenting with an uncomplicated episode of cystitis is unwarranted. |
Recurrent cystitis in women |
Pretreatment midstream urine (MSU) for MCS - the causative organism should be identified to differentiate between relapse (infection with the same organism) and reinfection (infection with different organisms). Multiple infections with the same organism (relapse) are, by definition, complicated UTIs (see below) and require further diagnostic tests. Most recurrent UTIs in women are uncomplicated infection caused by different organisms, and are generally not associated with underlying abnormalities and do not require further work-up of the genitourinary tract. |
Complicated UTI |
Anatomic or functional factors predispose the patient to recurrent or persistent infection, or treatment failure. |
Enlargement of the prostate Urinary tract obstruction Indwelling catheters Organism resistant to multiple antibiotics Vesicoureteral reflux |
Accurate urine MCS and susceptibility studies PLUS Follow-up urine cultures |
Acute pyelonephritis |
Should always be considered in patients who have severe rigors, hypotension, and/or shock. |
E. coli |
Blood cultures - positive in up to 20% |
Asymptomatic bacteriuria |
Pretreatment midstream urine (MSU) for MCS |
Pregnant women |
In pregnancy, a screening urine culture should be obtained towards the end of the first trimester of pregnancy. If screening urine culture is normal, a seconding urine screening should be offered in the third trimester. If screening positive, a monthly follow-up urine culture is recommended to detect asymptomatic relapsing bacteriuria. |
Renal transplants |
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UTI in men |
Suspect underlying prostatic disease in men with symptoms and signs of UTI. |
Prostate disease |
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Catheter-associated UTI |
Urine MCS |
UTI in children |
Pretreatment midstream urine (MSU) for MCS |
Anatomical abnormality esp. vesicoureteral reflux |
Either midstream, suprapubic or sample collected by placing a bag over the perineum (infants). Urological work-up including a voiding cystourethrogram, ultrasonography. |
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REFERENCES
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