L6: UTI Flashcards
Def of UTI
Urinary tract infection (UTI) is defined by the presence of bacteria in bladder urine.
Once the diagnosis of UTI is made, it is important to classify the location and severity of tissue invasion
Def of Acute pyelonephritis
Infection which involves the bacterial invasion of renal parenchyma
Def of Acute cystitis
Infection limited to superficial invasion of the bladder
Def of Asymptomatic bacteriuria
Presence of infected urine which produces
no-clinical symptoms
Epidemeology of UTI
Classification of UTI
- Acc to severity
- Acc to Site
Classification of UTI
- According to severity
Classification of UTI
- According to Site
Simple UTI
UTI with no fever, dysuria, frequency or urgency
Complicated UTI
- Fever, systemic toxicity
- Persistent vomiting, dehydration
- Renal angle tenderness, increased creatinine
Recurrent UTI
Second episode of UTI; usually within 6 months
Upper UTI
Lower UTI
Pathogenesis of UTI
Pathogenesis of UTI
- Causative Organism
mostly E.coli
Pathogenesis of UTI
- Method
When to suspect Acute pyelonephritis in Newborn?
When to suspect Acute pyelonephritis in Infants & Young Children?
When to suspect Acute pyelonephritis in Older Children?
When to suspect Acute cystitis in Children > 2 years?
DDx of Voiding symptoms in children > 2 years
- Vulvovaginitis (itching + vaginal discharge + inflamed vulva)
- Pin worm infestation
- Hypercalciuria
- Unstable bladder
Host Factors contribuiting to UTI
+++ Anatomical factors
Host Factors contribuiting to UTI
- Age
Higer in boys < 1 year & in girls < 4 years
Host Factors contribuiting to UTI
- Sex
- Females (2-4 folds higher)
- This may be the result of the shorter female urethra.
Because the incidence of UTI in male neonates is as high, if not higher, than female neonates
Host Factors contribuiting to UTI
- Race
White children have 2-4 folds higher than black (for not completely understood reasons )
Host Factors contribuiting to UTI
- Genetic
- Higher in first degree relatives
- Adherence of bacteria may be genetically determined.
Host Factors contribuiting to UTI
- dysfunctuinal elimination
- An abnormal elimination pattern (frequent or infrequent voids, urgency, constipation)
- Bladder and/or bowel incontinence
- Withholding maneuvers
Host Factors contribuiting to UTI
- Circumcision
(Uncircumcised male infants with fever have 4-8 fold higher prevalence)
Host Factors contribuiting to UTI
- Catheterization
(Increased Risk with Increased duration of bladder catheterization)
Host Factors contribuiting to UTI
- Anatomical abnormalities
- Urinary obstruction
- Vesicoureteral reflux
Anatomical abnormalities contributing to UTI
- Urinary Obstruction
Anatomical abnormalities contributing to UTI
- VUR
RF for Renal Scarring
CP of UTI in neonates (<28 days)
CP of UTI in in children (< 2 years)
CP of UTI in Older Children (> 2 years)
- Fever
- Abdominal pain
- Urinary symptoms (dysuria, urgency, frequency, incontinence, macroscopic hematuria)
Fever + chills + flank pain โ>
Pyelonephritis
Abdominal Ex in UTI
General Ex in UTI
Genital (Local) Ex in UTI
Atypical UTI
Recurrent UTI
Red Flags in UTI
Investigations for UTI
Labs & Rads
Methods of Urine Collection
Preservation of Urine
Urine Dipstick Analysis
Use of Leucocyte Esterase
- Suggestive of UTI
- However, +ve result doesnโt always signal UTI
Test Principle of Leucocyte Esterase
-Leukocyte esterase is present in neutrophils and can be assayed in urine by dipstick strips
Sensitivity & Specifity of Leucocyte Esterase
Sensitivity: 84%
Specifity: 78%
False Positive in Leucocyte Esterase
- Imipenem
- Clavulanic acid
False negative in Leucocyte Esterase
- Ascorbic acid
- Boric acid
- Gentamicin
- Nitrofurantoin
- Cephalexin
- Proteinuria
- Glycosuria
- Urobilinogen
Use of Nitrite
- Suggestive of UTI
- Not identify gram +ve infection (Lack nitrate reductase enzyme)
Test Principle in Nitrite
- bacterial enzyme nitrate reductase can convert urinary nitrate to nitrite.
Sensitivity & Specificity in Nitrite
- 50%
- 98% (Highly specific & low false +ve rate)
Microscopic Examination in UTI
Def of Pyuria
Sensitivity of Pyuria
Sensitivity is 89 % which means it suggests infection, but infection can occur in absence of pyuria
Specifity of Pyuria
Presence of WBCs in urine is not specific for UTI as pyuria can be present without UTI
Causes of Sterile Pyuria (False Positive)
- Renal TB
- Urethritis
- Inflammation near the bladder (appendicitis, Chrons disease)
- Intestinal nephritis
True UTI without +ve leukocyte esterase on dipstick analysis and > 5 WBC/HPF with standardized microscopy is โฆโฆ.
unusual
Absence of pyuria in presence of significant bacteriuria may occur in โฆ..
- Early in the course of UTI (before the local inflammatory response develops
- Bacterial contamination of the urine sample (e.g. from the urethra or periurethral)
- Colonization of the urinary tract (e.g. asymptomatic bacteriuria)
Pyuria & Bacteruria association
โฆ.. is the gold standard for the diagnosis of UTI.
Urine culture
Urine culture should be performed in the following groups, even if the dipstick and microscopic analysis are negative:
Urine culture interpretation in UTI
CBC in UTI
Read Dx of UTI from Notes
Imaging in Dx of UTI
To identify abnormalities of the genitourinary tract, including VUR and obstructive uropathies. It Includes:
- Renal bladder sonography.
- Voiding cystourethrogram (VCUG)
- Tc-99m DMSA scintigraphy
Indications of Imaging in Dx of UTI
Imaging in Dx of UTI
- Time of US
Immediately
Imaging in Dx of UTI
- value of US
VCUG in UTI
- Time
3-6 weeks after infection but can be done after completing of antibiotic therapy
VCUG in UTI
- Prophylactic Antibiotics
- Prophylactic oral antibiotics should be given for 3 days with VCUG taking place on the 2nd day
VCUG in UTI
- Uses
Technique of Tc-99m DMSA scintigraphy in UTI
What is the gold standard test for diagnosing acute pyelonephritis and renal scars?
Tc-99m DMSA scintigraphy
DMSA in UTI
- Disadvantages
However, it doesnโt distinguish lesions that will spontaneously resolve from those which cause renal scarring
DMSA in UTI
- How to overcome the drawbacks?
Thus, a delay of 4 - 6 months is needed following acute pyelonephritis to allow acute reversible lesions to resolve in order to diagnose renal scarring
Indications of Imaging in UTI
- Child < 6 months
Indications of Imaging in UTI
- Child 6m - 3 years
Indications of Imaging in UTI
- Children > 3 years
TTT of UTI
- Goals
TTT of UTI
- General Measures
TTT of UTI
- Hygeinic Measures
TTT of UTI
- TTT Protocol
- Empirical Therapy
- Early and aggressive antibiotic therapy is necessary to prevent renal damage.
- It is initiated while awaiting culture results in infants and young children who are at risk for UTI complications and children with underlying urologic abnormalities.
TTT of UTI
- Oral Antibiotics
TTT of UTI
- Parentral Therapy
TTT of UTI
- Other Meds
Sulpha combinations (TMP-SMX), amoxicillin, penicillin, or nitrofurantoin.
TTT of UTI
- Duration of Antibiotics
TTT of UTI
- For pyelonephritis
TTT of UTI
- For Cystitis
Suppressive Therapy in UTI
- Indications
VUR โ Till reflux resolves especially in children < 5 years of age.
Suppressive Therapy in UTI
- Duration
Antibiotic prophylaxis is continued for up to 6 months after surgical correction of VUR.
Suppressive Therapy in UTI
- Drugs
Suppressive Therapy in UTI
- SE of Cotrimocxazole
Avoid in children < 3 months age or G6PD def.
Suppressive Therapy in UTI
- SE of Nitrofurantoin
- GIT upset
- Avoid in children < 3 months age or G6PD def. or renal insufficiency.
Suppressive Therapy in UTI
- Advantages of Cephalixin
Drug of choice in 1st 3 months of life
Suppressive Therapy in UTI
- Precautions of Cifixime
selected circumstances only
DOC for suppressive therapy in UTI in first 3 months of life
Cephalexin
Prognosis of UTI
- Recurrent UTI
- HTN
- Renal scarring
Prognosis of UTI
- Recurrent UTI
Approximately 14% of children younger than 6 years with UTI have a subsequent UT.
Prognosis of UTI
- HTN
Hypertension can result from renal scar formation in patients who have had acute pyelonephritis, often in association with VUR or another urinary tract anomaly.
Prognosis of UTI
- Renal Scarring
Acute pyelonephritis has the potential to cause tubulointerstitial damage and renal scar formation.