UTIs

Question 1

What is leukocyte esterase test?

Answer 1

a marker for increased neutrophils using the urine dipstick.

PMN >10 is a + test

Question 2

What is the nitrite test?

Answer 2

It is a marker for most bacteria that cause UTI on the urine dipstick.
Most UTI bacteria cleave nitrates to nitrites

Question 3

What are the two types of infections that fall under the blanket term “UTI”?

Answer 3

1. Cystitis- infection of the bladder
2. Pyelonephritis- infection of the kidney

UTI do NOT includes infections of urethra, prostate gland, testes or epididymis.

Question 4

Describe how the epidemiology of UTI changes with age.

Answer 4

Infants boys due to contamination of the urethra with rectal flora (poor wiping technique)

Adults: Women > men due to proximity of urinary tract to vaginal tract, rectum, and the short urethra.

Elderly: Women > men, but there is an increase in older men due to prostate problems

Question 5

Describe the recurrence rates of UTIs.

Answer 5

Women - recurrence of 25%

Men- recurrence 50% (less likely to get them, but if they do, they will continue to come back)

Question 6

Describe the pathogenesis of UTI.

Answer 6

Bacteria in stool –> colonization of urethra, introitus–> bladder colonization—> REFLUX/OBSTRUCTION—> ascending infection

Question 7

What are the 3 main natural defense mechanisms the body has against UTIs?

Answer 7

1. lactobacillus of the perineal flora keep vagina pH t allow colonization
2. pH, osmolarity and urea in the urine inhibit bacteria (if the urine is free flowing)
3. Tamm-Horsfall proteins from renal tubular cells bind and capture mannose epitopes of bacteria with type 1 fimbrae

Question 8

What are the risk factors for children to get UTI?

Answer 8

1. anatomical abnormality

2. vesicouteral reflux (VSR) which sends urine from bladder back up through the ureter and to kidneys

Question 9

What are the three anatomical reasons why women are more likely to get UTI than men?

Answer 9

1. short distance anus –> urethra
2. short distance vagina–> urethra
3. short urethral tract–> less distance for the bacteria to go to get to the bladder

Question 10

What is the most common risk factor for UTI in young women? Why?

Answer 10

sexual intercourse is the most common risk factor (honeymoon cystitis) because

1. it leads to transient urethral edema and obstruction of urine flow
2. spermicide and antimicrobials affect normal vaginal flora

Question 11

What are the 5 most most common risk factors for UTI in older women?

Answer 11

1. hormonally associated change in the mucousa (estrogen is protective) after menopause
2. incontinence
3. antibiotic use
4. history of prior UTI
5. sex

Question 12

Why does pregnancy increase the risk of developing a UTI?

Answer 12

1. physical/hormonal changes
2. loss of ureteral and bladder muscle tone leading to functional obstruction of urine flow
3. Uterine bulk can compress the right ureter leading to hydroureter and hydronephrosis
4. VUR

Question 13

What are the risk factors for men developing UTI?

Answer 13

1. BPH with age can decrease or obstruct urinary outflow
2. incontinence (diabetic nephropathy, vascular disease)
3. institutional settings

Question 14

What are the typical infecting organisms for UTI caused by catheter (CAUTI)?

Answer 14

enteric flora, skin flora, environmental organisms

Question 15

What are the virulence factors associated with UPEC (uropathogenic E. coli)?

Answer 15

1. Flagella
2. adhesins
3. Toxins
4. siderophores

Question 16

What are the 2 types of adhesins UPEC possess?
Which is more likely to cause cystitis?
Which is more likely to cause pyelonephritis?

Answer 16

Adhesins are pili or fimbrae that allow adhesion to epithelial cells of the colon, vagina, and uroepithelium.

1. P fimbrae- invade kidney (p = pyelonephritis)
2. Type I fimbrae- mannose sensitive and adhere to mannose receptor sites on Tamm Horsfall proteins. These are more likely to cause lower tract infections

Question 17

What are the 3 main toxins associated with UPEC?

Answer 17

1. Hemolysin- cytotoxic injury to PMNs and uroepithelial cells [children with UTI, adult upper UTI]
2. Cytotoxic necrotizing factor 1 (CNF1) - cytoskeletal rearrangement of cells and apoptosis of bladder cells
3. Secreted autotransporter proteins (Tsh, Sat, Pic) with serine protease activity

Question 18

What is the function of siderophores of UPEC?

Answer 18

acquire iron for the bacteria

Question 19

What is an uncomplicated UTI?
Is it more commonly cystitis or pyelonephritis?
What are the offending organisms?

Answer 19

It affects women without anatomical abnormalities or catheters.
It can be cystic or pyelonephrotic.
The offending organism is usually monomicrobial and is:
1. E coli
2. klebsiella
3. proteus
4. Staph saprophyticus -CONS is occassional

Question 20

What makes a UTI “complicated”?

Answer 20

1. male patients
2. females with other risk factors (pregnant, instrumentation, obstruction)

It can be mono or polymicrobial depending on the underlying issue

Question 21

What is the most common infecting organ for a child UTI?

neonates, anatomic abnormalities

Answer 21

Enteric flora.

Neonates- GB strep (from mother)

Anatomic abnormalities, primary immunodeficiency

1. proteus mirabilis
2. staphylococcus aureus
3. CONS

Question 22

A patient comes to see you and has fever chills, malaise, sepsis, flank pain, dysuria.

Lab tests show leukocytosis, pyuria, bactiuria, +/- bacteremia. There are occasional WBC casts.

What is the likely diagnosis and location?

Answer 22

Pyelonephritis- upper tract (kidneys, ureter)

Question 23

A patient presents with dysuria, frequency and suprapubic pain.

Lab findings show pyuria and bacteriuria.

What is the likely diagnosis and location?

Answer 23

Cystitis in the bladder

Question 24

A patient comes for a routine physical. They dont have any symptoms, but lab results show bacteriuria and pyuria.

What is the likely cause and location?

Answer 24

Asymptomatic bacteriuria in the lower urinary tract

Question 25

The signs and symptoms of UTI are general descriptions and cannot be relied on for diagnosis. What should be included on the differential if a patient has UTI-like symptoms?

Answer 25

1. vaginitis 2. urethritis (esp if chlamydia is suspected) 3. structural urethra abnormalities 4. PID 5. nephrolithiasis 6. appendicitis 7. prostatitis

Question 26

What all is assessed by the urine dispstick?

Answer 26

SG, pH, leukocyte esterase, blood, nitrite, bilirubin, urobilinogen, negative proteins, glucose

Question 27

What findings in the urinalysis cannot be found on the dipstick but require microscopic examination?

Answer 27

RBCs, WBCs, casts, crystals

Question 28

What 5 lab findings are most suspicious for a UTI?

Answer 28

1. + leukocyte esterase 2. Nitrite 3. WBCs 4. casts 5. +/- hematuria

Question 29

Why is nitrite indicative of a bacterial infection? | What is a limitation of the nitrite test?

Answer 29

We get nitrates in our diet. Bacteria in the urine are able to convert the nitrate to nitrite Limitation: urine needs to be incubated for a sufficient amount of time in the bladder for the test to be + (4 hours) so you will get false - if: 1. not enough nitrate in diet 2. pee not in bladder for 4 hours 3 .E. faecalis- does not nitrate--> nitrite

Question 30

Sterile pyuria (PMN with no bacterial infection) can be seen in what 7 scenarios?

Answer 30

1. urine contamination 2. chronic interstitial nephritis 3. kidney stones 4. uroepithelial tumors 5. interstitial cystitis 6. renal tuberculosis 7 chlamydia

Question 31

What 3 plates are urine cultures streaked on?

Answer 31

1. BA- non-selective 2. MacConkey's - selects gram neg, differentiates lactose fermenters from non-fermenters 3. CNA- selects for gram +

Question 32

How should a urine sample be collected? What CFU is reflective of infection?

Answer 32

Patients should clean the urethral meatus, discarded the first few ml of urine and then collected the remainder in a sterile cup. (mid-stream urine specimen) CFU > 10 ^5 is infection Symptomatic women with pyuria will have colony count between 10^5 and 10^2

Question 33

If a patient with a catheter is symptomatic, what CFU determines a UTI?

Answer 33

10^5 or more regardless of urinanalysis | 10^3 with evidence of pyuria

Question 34

If a child is suspected of UTI, how should sample for culture be collected? What determines + culture?

Answer 34

1. catheterization 2. suprapubic aspiration 10^4 CFu plus symptoms = UTI

Question 35

What imaging tests are indicated for cystitis?

Answer 35

none

Question 36

What imaging tests are indicated for pyelonephritis?

Answer 36

Ultrasound and CT can help show renal or perinephric abscesses, urolithiasis, anatomic complications.

Question 37

In children, what imaging test is most frequently done if symptomatic for a UTI?

Answer 37

1. renal and bladder sonography | 2. voiding cystourethrogram based on ultrasound results if suspected VUR

Question 38

What is used to calculate antimicrobial susceptibility patterns?

Answer 38

Antibiograms Treat with empiric therapy based on the susceptibility results

Question 39

What group of people is treatment of asymptomatic bacteriuria absolutely indicated in?

Answer 39

1. Preggos. Screen at first visit | 2. patients to undergo urologic procedures with invasion of the mucousa

Question 40

What 4 factors determine the duration of the antibiotic given?

Answer 40

1. the drug 2. the type of infection 3. patient characteristics 4. clinical response

Question 41

If treating pyelonephritis, an antibiotic should be chosen that has ____________ distribution rather than ____________________. DO NOT use ____________ or ______________ alone.

Answer 41

systemic distribution rather than concentrating in the urine. Do NOT use nitroferintoin or ampicillin alone. (use ampicillin with gentamycin)