Urinary Tract Infection Lecture Notes PDF

Urinary tract infection Dr.Basma Adel MBChB ,FICMS ped, FICMS ped neurology Fifth grade 2023-2024 At the end of this lecture you should know: ✓ Epidemiology ✓ Etiology ✓ Pathology ✓ Risk factors of UTI ✓ Clinical man...

Urinary tract infection Dr.Basma Adel MBChB ,FICMS ped, FICMS ped neurology Fifth grade 2023-2024 At the end of this lecture you should know: ✓ Epidemiology ✓ Etiology ✓ Pathology ✓ Risk factors of UTI ✓ Clinical manifestation ✓ Investigations ✓ Complications ✓ Treatment ✓ Vesico ureteral reflux Epidemiology Approximately 3% of girls and 1% of boys have a UTI during their prepubertal years with the highest incidence in the first year of life. It is only during the first year of life that the incidence of UTIs in males exceeds that in females; during this period uncircumcised boys are at 10-fold greater risk of developing a UTI compared to circumcised boys After 12 months of age, UTI in healthy children usually is seen in girls (short urethra predisposes girls to UTIs).  Etiology UTIs are caused primarily by colonic bacteria. Escherichia coli causes 54–67% of all UTIs, followed by Klebsiella spp. and Proteus spp., Enterococcus, and Pseudomonas. Other bacteria known to cause UTIs include Staphylococcus saprophyticus, group B streptococcus, and, less commonly, Staphylococcus aureus, Candida spp., and Salmonella spp Pathogenesis and Pathology Nearly all UTIs are ascending infections. The bacteria arise from the fecal flora, colonize the perineum, and enter the bladder via the urethra. In uncircumcised males, the bacterial pathogens arise from the flora beneath the prepuce. In some cases, the bacteria causing cystitis ascend to the kidney to cause pyelonephritis.  Rarely, renal infection occurs by hematogenous spread, as in endocarditis or in some bacteremia neonates. Children of any age with a febrile UTI can have acute pyelonephritis and subsequent renal scarring, but the risk is highest in those younger than 2 yr. of age. Clinical Manifestations and Classification Urinary tract infections include : Cystitis (infection localized to the bladder) Pyelonephritis (infection of the renal parenchyma, calyces, and renal pelvis) Renal abscess, which may be intrarenal or perinephric. Cystitis (lower UTI) There is only bladder involvement, Symptoms include: o Dysuria o Urgency o Frequency o Suprapubic pain o Incontinence o And possibly malodorous urine. o Cystitis does not cause high fever and does not result in renal injury. Acute hemorrhagic cystitis, though uncommon in children, is often caused by e. Coli and adenovirus types 11 and 21.  Pyelonephritis(UPPER UTI) Pyelonephritis is characterized by any or all of the following: Abdominal, back, or flank pain. Fever, malaise (Fever may be the only manifestation) Nausea, vomiting and diarrhea. Pyelonephritis is the most common serious bacterial infection in infants younger than 24 mo of age who have fever without an obvious focus.  CLINICAL MANIFESTATIONS The symptoms and signs of UTI vary markedly with age. NEONATES Few have high positive predictive value in neonates, with : i. Failure to thrive ii. Feeding problems iii. Jaundice iv. Diarrhea, vomiting v. Fever as the most consistent symptoms.  INFANTS 1 MONTH TO 2 YEARS may present with: i. Feeding problems ii. Failure to thrive iii. Diarrhea, vomiting iv. Unexplained fever. The symptoms may masquerade as gastrointestinal illness, with colic, irritability, and crying periods.  At 2 years of age, children begin to show the classic signs of UTI in addition to GIT symptoms such as: i. Urgency ii. Dysuria iii. Frequency iv. Abdominal or back pain. 6-18years old urgency, frequency, abdominal or flank pain.  The presence of UTI should be suspected in all infants and young children with unexplained fever and in patients of all ages with fever and congenital anomalies of the urinary tract Diagnosis UTIs may be suspected based on symptoms or findings on urinalysis, or both. Urinalysis(GUE) Urine culture Imaging studies URINE CULTURE a urine culture is necessary for confirmation of diagnosis and appropriate therapy. There are several ways to obtain a urine sample; some are more accurate than others.  IN TOILET-TRAINED CHILDREN: a midstream urine sample usually is satisfactory; the introitus should be cleaned before obtaining the specimen. IN CHILDREN WHO ARE NOT TOILET TRAINED: A catheterized or suprapubic aspirate urine sample should be obtained. Alternatively, the application of an adhesive, sealed, sterile collection bag after disinfection of the skin of the genitals can be useful only if the urinalysis or culture is negative. A suprapubic aspirate generally is unnecessary. How to obtain a urine sample  Urine culture The diagnosis of UTI: In infants and young children : requires the presence of both pyuria and at least 50,000 CFU/mL of a single pathogenic organism. For older children and adolescents: more than 100,000 CFU/mL indicates infection. Perineal bags for urine collection are prone to contamination and are not recommended for urine collection for culture.  Pyuria (leukocytes on urine microscopy) suggests infection, but infection can occur in the absence of pyuria; this finding is more confirmatory than diagnostic. Nitrites and leukocyte esterase usually are positive in infected urine. Microscopic hematuria is common in acute cystitis, but microhematuria alone does not suggest UTI Sterile pyuria (positive leukocytes, negative culture) may occur in: partially treated bacterial UTIs viral infections renal tuberculosis renal abscess urinary obstruction inflammation near the ureter or bladder eg.appendicitis B-CBP in upper UTI, there is leukocytosis (neutrophilia), ↑ ESR & CRP C- blood cultures should be drawn before starting antibiotics if possible as sepsis is common in pyelonephritis, particularly in infants and any child with obstructive uropathy D- Imaging studies are used to identify the anatomical abnormalities ,these include:- 1. Ultrasound of the bladder and kidney is indicated initially for infants and non–toilet- trained children with first-time febrile UTIs to exclude structural abnormalities or detect hydronephrosis. 2.VCUG is indicated if : U/S study is abnormal (hydronephrosis, scarring, or other findings suggesting obstruction or congenital abnormality). after a recurrent febrile UTI. The timing of VCUG 2-6 wks. after treatment (to allow inflammation in bladder to resolve to reduce the incidence of VUR. 3. A technetium-99m dimercaptosuccinic acid (DMSA) scan can identify acute pyelonephritis and is most useful to define renal scarring as a late effect of UTI. Treatment Acute cystitis should be treated promptly to prevent possible progression to pyelonephritis. If the symptoms are severe, presumptive treatment is started pending results of the culture. If the symptoms are mild or the diagnosis is doubtful, treatment can be delayed until the results of culture are known, and the culture can be repeated if the results are uncertain. A 3- to 5-day course of therapy with: a) trimethoprim-sulfamethoxazole (TMP-SMX) (6-12 mg TMP/kg/day in 2 divided doses) or trimethoprim is effective against many strains of E. coli. b) Nitrofurantoin (5-7 mg/kg/24 hr in 3-4 divided doses) also is effective and has the advantage of being active against Klebsiella and Enterobacter organisms. c) Amoxicillin (50 mg/kg/24 hr in 2 divided doses) also may be effective as initial treatment but has a high rate of bacterial resistance In acute febrile UTIs a course of antibiotics for 7-14 days is required. Indication for hospital admission and intravenous (IV) rehydration and IV antibiotic therapy: Children who are dehydrated, are vomiting, are unable to drink fluids. 1 mo. of age or younger. have complicated infection, or in whom urosepsis is a possibility.  For hospitalized children, parenteral treatment with : ✓ Ceftriaxone (50 mg/kg/24 hr, not to exceed 2 g) ✓ Cefepime (100 mg/kg/24 hr q 12 h) ✓ Cefotaxime (100-150 mg/kg/24 hr in 3-4 divided doses) Is a reasonable choice until culture results are available. Oral 3rd-generation cephalosporins such as cefixime are as effective as parenteral ceftriaxone against a variety of Gram-negative organisms other than P. aeruginosa Cephalexin may also be considered given the increasing resistance of Gram-negative organisms to amoxicillin. The oral fluoroquinolone ciprofloxacin is an alternative agent for resistant microorganisms, particularly P. aeruginosa, in patients older than 17 yr. The potential side effects of fluoroquinolones should be weighed against the benefits of this antibiotic selection. It also has been used on occasion for short-course therapy in younger children with P. aeruginosa UTIs. Levofloxacin is an alternative PREVENTION Primary prevention is achieved by promoting good perineal hygiene and managing underlying risk factors for UTI, such as chronic constipation and daytime and nighttime urinary incontinence. Acidification of the urine with cranberry juice is not recommended as the sole means of preventing UTI in children at high risk  Urologic conditions for recurrent UTIs that might benefit from long-term prophylaxis include : ✓ neuropathic bladder ✓ urinary stasis and obstruction and urinary calculi. ✓ severe vesicoureteral reflux ✓ In a child with recurrent UTIs. Antimicrobial prophylaxis using trimethoprim or nitrofurantoin at 30% of the normal therapeutic dose once a day. TMP-SMZ, amoxicillin, or cephalexin can also be effective  Vesico ureteral reflux: Vesicoureteral reflux (VUR) is retrograde flow of urine from the bladder to the ureter or kidney. VUR is the most common anatomic abnormality found in infants and young children with febrile urinary tract infection (UTI). There is a genetic predisposition to primary VUR with an increased risk in children with affected parents or siblings. Secondary VUR may be present in children with other urinary tract anomalies(with ureteral duplication, neurogenic bladder, posterior urethral valves, prune belly syndrome). CLINICAL MANIFESTATIONS The most common clinical manifestation of VUR is febrile UTI. Recurrent febrile UTI is more likely in children with higher grade VUR. Could be asymptomatic. DIAGNOSTIC STUDIES Renal ultrasound is typically obtained first to evaluate the kidneys and urinary tract. Voiding cystourethrogram (VCUG) is required to confirm the diagnosis of VUR in a child with recurrent febrile UTI. MANAGEMENT Grades 1 and 2 primary VUR will likely self- resolve. Many cases of grades 3 and 4 primary VUR resolve when VUR is diagnosed before 2 years of age and is unilateral. Severe (grade 5) primary VUR and secondary VUR are less likely to resolve spontaneously. Management options for a child with VUR include surveillance, medical therapy, and surgical intervention.. Indications for surgical intervention include VUR that does not resolve over time or is complicated by recurrent febrile UTI despite medical therapy.  Medical management is recommended in children with Grade I-III VUR. A trial of medical treatment is indicated in patients with Grade IV VUR. Of the patients with Grade V , VUR surgery is the only option.