URINARY TRACT INFECTIONS LEC NO 4 DR: BAKIR RAHIM RASHID MBChB-DCH-FICMS

Definition and prevalence UTI is associated with multiplication of organisms in the urinary tract.. DEFINITION: defined as the presence of more than 100.000 organism per ml. in the midstream urine sample OR presence of any organism from suprapubic puncture sample of urine. The prevalence of UTI varies markedly with age and sex. In the first year of life it is more common in male with a male to female ratio of 2.8:1 while in other age groups it is much more common in females reaching a ratio of 1:10.

Etiology and pathogenesis UTIs are caused mainly by colonic bacteria , 75-90% of all infections are caused by E.coli followed by Klebsiella and Proteus.Staphyococcus saprophyticus and enterococcus may be the cause. Viral infections particularly Adenovirous may cause cystitis. Nearly all UTIS are ascending infections. In rare cases renal infection may occur by hematogenous spread. Once the organism gain entrance to the bladder the severity of the infection may reflect the virulence of the bacteria and presence of predisposing factors.

Risk Factors for Urinary Tract Infections 1-Voiding dysfunction: In girls UTIs often occur at the onset of toilet training because of voiding dysfunction that occurs at this age. The child is trying to retain the urine to stay dry, yet the bladder may have uninhibited contractions forcing urine out, the result may be high pressure turbulent urine flow or incomplete bladder emptying, both of which increase the likelihood of bacteruria. Voiding dysfunction may occur in the toilet trained child who void infrequently.

2-Obstructive uropathy. 3- urethral instrumentation 2-Obstructive uropathy. 3- urethral instrumentation. 4-anatomic abnormalities. 5- vesicoureteral reflux. 6-neuropathic bladder increase the risk of UTI. 7- pinworm infestation. 8- constipation. 9- uncircumcised male, 10-wiping from back to front. 11-tight under wear. 12- bubble bath.

CLASSIFICATION There are three basic types of UTI: 1-Pyelonephritis. 2-Cystitis. 3-Asymptomatic bacteriuria.

CLINICAL MANIFISTATIONS Pyelonephritis: There is bacterial involvement of the upper urinary tract. Clinically characterized by any or all of the following: 1- Abdominal or flank pain. 2-Fever:Pyelonephritis is the most common serious bacterial infections in infants less than two years of age presenting with fever with out a focus. 3-Malase,nausia,vomiting and occasionally diarrhea. 4-Newborns may show nonspecific symptoms like poor feeding,irritability,and weight loss. -Acute pyelonephritis may result in renal injury.

CLINICAL MANIFISTATIONS contn. Cystitis: Indicate that there is bladder involvement; symptoms include: 1-dysuria 2-urgency 3-frequency 4-suprapubic pain 5-incontinence 6-malodorous urine -Cystitis does not cause fever and does not result in renal injury.

CLINICAL MANIFISTATIONS cont.. Asymptomatic bacteriuria: In this condition there is a positive urine culture without any manifestations of infection. It is most common in girls. The incidence declines with increasing age. This condition is benign and does not cause renal injury in pediatric age group.

DIAGNOSIS A UTI may be suspected based on symptoms or finding on urine analysis or both , but confirmation by urine culture is necessary. Urine can be obtained by several ways for analysis and culture: 1-In toilet-trained children, a midstream urine sample is satisfactory. 2-In infants, the application of an adhesive,sealed,steriale collection bag after disinfection of the skin of the genitals can be useful. 3-A sample of urine can be obtained by catheterization for greater accuracy .

DIAGNOSIS -The urine sample that are obtained should be used with in 60 munities, because if the urine sits at room temperature for more than 60 min overgrowth of a minor contaminant may falsely suggested UTI. -Urine analysis: Pyuria suggests infection, but infection can occur in the absence of pyuria.Conversely,pyuria can be present with out UTI. Nitrites and leukocyte esterase usually are positive in the infected urine. Microscopic hematuria is common in cystitis.

If the child is asymptomatic , and the urine analysis is normal UTI is unlikely, but if the child is symptomatic , a UTI is possible even if the urinalysis result is negative.

URINE CULTURE: urine culture is necessary for confirmation of UTI ,and for proper treatment. If the culture shows>100000 colonies of a single pathogen, or if there are 10000 colonies and the child is symptomatic the child is considered to have UTI. CBC: With acute UTI there is leukocytosis,neutrophilia with elevated ESR ,and C-reactive protein. BLOOD CULTURE: in any infants with pyelonephritis or obstructive uropathy blood culture should be done because there is possibility of sepsis.

IMAGING STUDIES The goal of imaging studies in children with UTI is to shows anatomic abnormalities that may predispose to UTI. 1-Sonography:in child with febrile UTI a renal sonogram should bed obtained to rule out hydronephrosis and structural abnormalities. In child with acute pyelonephritis show enlarged kidney. Renal sonography may also detect pyonephrosis.

2-Voiding cystourethrogram(VCUG): it is indicated for girls who have had 2 or 3 UTI within a period of 6 months, and in boys with more than one UTI.it is used to detect vesicoureteral reflux. 3-Renal scanning: renal scanning with technetium-labled DMSA is useful for diagnosis of acute pyelonephritis. The DMSA is the most sensitive and accurate study for demonstrating scarring.

4-Intraveinous urogram(IVU): Is not as sensitive as DMSA scan for detecting renal scarring . 5- CT scan can also be use to detect renal scare. 6-Cystoscopy:In the past were often performed in girl with UTI ,but it provide nothing to the therapeutic decision in child with UTI and are contraindicated.

TREATMENT Cystitis should be treated promptly to prevent progression to pyelonephritis. Choice of antibiotic should be biased on the result of culture and sensitivity.in mild cases treatment can be delayed until the result of culture came back, but in severe cases treatment should be started immediately after taking a sample of urine for culture. A 3 to 5 days course therapy with any of the following is effective: 1-Trimethoprim-sulfamethoxazole. 2-Nitrofurantoin. 3-amoxicillin.

TREATMENT cont. Acute pyelonephritis: Treatment with broad spectrum anti biotic for 10-14 days is preferable. Oral therapy with third generation cephalosporin's as cefixime is effective ,ciprofloxacin is an alternative agent for resistant cases.

Indications for hospital admission: 1-Dehydration. 2-Vomiting Indications for hospital admission: 1-Dehydration. 2-Vomiting. 3-Unable to drink fluid. 4- age < 1 month. 5- Sepsis. Those admitted to hospital should be treated with intravenous rehydration and intravenous antibiotics .parenteral treatment with ceftriaxone or ampicillin and aminoglycoside is preferable.

TREATMENT cont. -In children with renal or perirenal abscess or with infection in obstructed urinary tracts often require surgical or percutaneous drainage. -In a child with recurrent UTI the underlying causes should be treated. -Prophylaxis against reinfection may be necessary in some child with( neurogenic bladder ,stasis,refluxes,stone,obstruction) trimethprime-sulfamithxazole,nitrofurantoin,amoxicillin at one third of therapeutic doses is effective.

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