Dr. Rubin -- Urinary Tract Infection Flashcards
% chance of UTI being the cause of fever in feverish newborns
UTI
3 examples of sites that a UTI can occur
- Bladder
- Kidney
- Prostate
Basically, anywhere along the urinary tract
Define cystitis
Infection at level of bladder
Define pyelonephritis
Infection involving renal parenchyma (kidney)
Define renal abscess
Puss collection with severe pyelo or spread from blood stream
Define bacteria prostatitis
Infection of the prostate gland
Source of bacteria for UTI
Gut flora
5 factors that facilitate the ascent of gut flora bacteria up the urinary tract
- Pili
- Obstruction
- Neurologic disease leading to poorly functioning bladder
- Pregnancy
- Reflux (urine going up the ureters)
2 most common pathogens of UTI
- E. coli (85%)
- *Staphylococcus Saprophyticus *(5 - 15% in young women)
3 virulence factors of E. coli that explain why it is the most common pathogen for UTI
- P Fimbriae/pili allow for bacteria to attach
- Hemolysins (may break down host cells)
- Aerobactin (scavenge for iron)
4 pathogens that account for a minority of causes of UTI
- Enterobacteriaceae
- Enterococcus
- Yeast
- Group B streptococcus
3 urea splitting organisms that may form struvite stones in UTI
- Proteus
- Morganella
- Providencia
What is the likely pathogen if the UTI involves an indwelling plastic (i.e. catheter)
Could be anything because a biofilm forms and traps unusual organisms
Most important behavioral factor to prevent UTI
Most important = periodic, complete, normal voiding (wash out bacteria and cells to which they are attached)
Describe 1 behavioral risk for UTI and why
Sexual intercourse:
- Mechanically allows bacteria to ascend (but voiding can clear bacteria)
- Spermicide use kills normal flora (lactobacillus), which maintains and acidic milieu and prevents colonization
How can a UTI become complicated
If a patient has structural or functional abnormalities of the GU tract that compromise voiding
7 structural or functional abnormalities of the GU tract that can compromise voiding
- Obstruction to flow
- UPJ obstruction
- Stones
- Posterior urethral valves (pediatric)
- Increased access
- Indwelling urinary catheters
- Vesico-ureteral reflux
- Preganancy
- Urinary stasis due to hormones
- Obstruction from fetus
5 lower tract symptoms of UTI
- Dysuria
- Frequency
- Urgency
- Discomfort in suprapubic or lower back area
- Gross hematuria
2 situations where UTI is unlikely
If symptoms are in between voids or if there is vaginal symptoms
Upper tract or pyelonephritis symptoms
- High fever
- CVA tenderness
8 presenting symptoms of UTI in pediatrics
- Fever
- Irritability
- Afebrile
- Poor feeding
- Vomiting
- Diarrhea
- Jaundice
- Poor weight gain
Potential presentation of UTI due to indwelling catheter
May just be fever alone
Presentation of UTI with spinal cord injury
Increased spasticity of lower limbs
Presentation of UTI with MS
Increased fatigue and deterioration
Clinical presentation of UTI in senior citizens
Altered sensorium
3 symptoms of UTI in the presence of bacterial prostatitis
- Fever
- Pelvic pain
- Urinary retention
Most sensitive urinalysis test
Leukocyte esterase
Good urinalysis method to rule in UTI
Nitrite
3 cases where nitrite urinalysis can produce a false negative
- No nitrates in diet
- Insufficient dwell time in bladder
- Non-enzyme producing organism = enterococcus
Disadvantage of using blood and/or protein as UTI test
Poor sensitivity and specificity
2 disadvantages of using microscopy asa urinalysis technique
- Technologist dependent (very wide range of sensitivity and specificity)
- If analyzed > 3 hours after collection, sensitivity drops by 35%
Describe how to maximise sensitivity and specificity of urinalysis (4)
Combination of tests:
- LE or nitrate + = sens 83 - 100% and spec 68 - 98%
- Microscopy for WBC and bacteria = sens 99%
- Anything positive on dip/microscopy
- Sens = 100%, but spec poor
- If dip/microscopy all negative
- NPV = 100%
3 ways to limit contamination of urine culture
- Mid stream
- In-out cath
- Bladder taps (for infants <5 months)
4 general principles of UTI treatment
- Empiric therapy may be needed to be modified based on susceptibility testing
- Antimicrobials excreted in urine preferred
- Cystitis = only urinary antibacterial activity necessary
- Pyelonephritis = need adequate drug level in urine and tissue and possible blood level
3 conditions where urine culture should be sent in cystitis
- Uncertain symptoms
- History of frequent relapse
- Pregnant
3 antibiotics for cystitis
- Most common = TMP/SMX (Septra) for 3 days
- Quinolone (Cipro) for 3 days
- Nitrofurnatoin (local bacterostatic) for 7 days
4 treatment options for pyelonephritis
- Ampicillin and aminoglycoside (Genta)
- Genta alone
- 3rd generation cephalosporin (Ceftriaxeon)
- Oral = Septra or quinolone
NOTE: Tailor based on C&S results
When to consider complicated infection in pyelonephritis
If not improvement by day 3
2 conditions where treatment for asymptomatic bacteriuria is indicated and why
- Pregnancy = can become pyelonephritis, which may precipitate premature labor
- Urological procedure imminent = compromise of mucosa can lead to complication of spread into bloodstream
Criteria for recurrent uncomplicated UTIs meriting prophylaxis
2 episodes every 6 months or 3 every year
(“Honeymoon cystitis”)
2 prophylaxis treatments for recurrent uncomplicated UTIs
- Daily or alternate day low does Septra, OR following intercourse
- Nitrofurantoin
Pro and con of using prophylactic Septra for recurrent uncomplicated UTIs
- Reduce gram negative flora in periurethral area
- BUT increase incidence of resistant UTIs
Pro and con of nitrofurantoin as prophylaxis against recurrent uncomplicated UTIs
- Less impact than Septra on colonizing flora
- Can intermittently sterilize urine through high urinary antimicrobial levels
2 risks of UTI in children
- Higher likelihood of having blood spread and complications (i.e. meningitis)
- Higher likelihood of having some anomaly of the urinary tract
Age that requires septic workup including lumbar puncture
Under 6 - 8 weeks of age
Age that requires IV treatment
Under 1 month
When to use VCUG for infants with UTI and its purpose
Purpose = To detect reflux from bladder up the ureter
Atypical UTI:
- Recurrent
- Non E. coli
- Abnormal ultrasound
- Bacteremia
When to consider prophylaxis for infants with UTI
If there is reflux (at least until they are toilet trained)
Difference in sex for incidence of UTI in neonatal period
- 1.5 - 5 times males : females
- Highest in uncircumsized males
- Incidence decreases in boys and increases in females during the first 6 months
- By age 1 females outnumber boys 3 - 10:1
Why is an uncircumsized penis a risk factor for UTI?
Uropathogenic organisms preferentially adhere to the mucosal inner surface of the foreskin rather than the keratinized external surface. Phimosis likely plays a role
Differences between signs and symptoms of neonates (i.e. compared to adults) (5)
- Lower grade fever OR afebrile
- Fever is shorter and disappears more promptly on treatment
- May just have no fever with:
- Poor feeding
- Lethargy
- Grunting
- Poor weight gain
- OR pulminant sepsis
- May be asymptomatic besides jaundice
VCUG use based on sex for children >2 years with their first UTI
- VCUG for all boys, regardless of age
- VCUG for girls, if recurrent and abnormal ultrasound
