Micro

Question 1

What is the incidence of UTI in kids?

Answer 1

infants <3 months boys more common due to anatomic abnormalities
preschool girls more due to hygiene problems

Question 2

Why does the incidence of UTIs in men increase over the age of 65?

Answer 2

BPH, urinary retention, incontinence, institutionalization

Question 3

What kinds of microbes are involved in long term vs. short term CAUTI?

Answer 3

long term - polymicrobial

short term - monomicrobial

Question 4

What are host defenses against UTIs?

Answer 4

vaginal pH <4.5
pH and high urea of urine
free unobstructed flow of urine
Tamm-Horsfall proteins from renal tubular cells capture bacteria with Type I fimbrae

Question 5

What is the main mechanism of UTIs in children?

Answer 5

vesicoureteral reflux

Question 6

What are red flags that can suggest an underlying anatomic abnormality in kids with UTIs?

Answer 6

recurrent inf
palpable kidney or poor urinary stream
unusual organisms
bacteremia or clinical sepsis
failure to respond within 48 hours
older boy
known dilation or abnormality of urinary tract on sonogram

Question 7

Why do women get UTIs much more commonly than men?

Answer 7

shorter urethra

less distance from urethra to anus or vagina

Question 8

What is the biggest risk factor for UTI in young women?

Answer 8

sex - transient urethral edema and obstruction of urinary flow
normal flora impacted by spermicides and recent antimicrobial exposure

Question 9

What are risk factors for UTIs in older women?

Answer 9

post menopause - hormonal mucosal changes
urinary incontinence, antibiotic exposure, history of previous UTI
also still sex

Question 10

How does pregnancy impact the risk for UTIs?

Answer 10

urinary retention and stasis due to enlarging uterus
ureteral compression (R>L)
loss of ureteral and bladder tone causes stasis
vecisoureteral reflex

Question 11

Which bacteria cause UTIs in pregnant women in order from most common to least?

Answer 11

E. Coli
Klebsiella
Enterobacter
Proteus
Group B strep

Question 12

What is the normal response of UTIs in pregnancy to treatment with antibiotics and what are some complications?

Answer 12

Should resolve w/i 48-72 hrs
nephrolithiasis
intrarenal abscess
perinephric abscess
resistance to antibiotics
alveolar injury can cause ARDS and edema

Question 13

How do catheters cause UTIs?

Answer 13

if more than 30 days, bacteriuria is universal
disrupt epithelial mucosa and expose binding sites
biofilms form from exopolysaccharides
recognized by bacterial adhesins

Question 14

What are adhesins associated with uropathogenic strains of E coli?

Answer 14

p fimbrae involved in invading kidney

type I fimbrae - mannose sensitive, more often in lower tract inf than upper UTI

Question 15

What are toxins associated with uropathogenic strains of E coli?

Answer 15

hemolysin - injury to neutrophils and uroepithelial cells, children with UTIs and adults with upper UTIs
CNF1 - causes cytoskeleton rearrangement in host cells and apoptosis in bladder cells
Secreted autotransporters (Tsh, Sat, Pic) - serine protease activity

Question 16

How do siderophores play a role in uropathogenic E coli?

Answer 16

allow bacteria to acquire host iron

Question 17

What are uncomplicated UTIs?

Answer 17

women without anatomic abnormalities
usually monomicrobial
usually enteric GNRs, occasionally CAN staph or enterococci

Question 18

What are complicated UTIs?

Answer 18

any male patient
female patient with other risk factors - obstruction, instrumentation, pregnancy
mono or poly microbial
children

Question 19

What pathogens are associated with UTIs in children?

Answer 19

neonates have group B strep

if proteus, s aureus, or CAN staph found - consider anatomic abnormalities or immunodeficiency

Question 20

What does the differential diagnosis of UTIs include?

Answer 20

vaginitis, urethritis (esp due to STDs like chlamydia), structural urethral abnormalities, PID, nephrolithiasis, appendicitis, prostatitis

Question 21

What kinds of symptoms do children with UTIs present with?

Answer 21

nonspecific signs like fever, fussiness, diarrhea, constipation, vomiting, poor feeding, enuresis, prolonged neonatal jaundice
no rash

Question 22

What does a dipstick urinalysis detect?

Answer 22

specific gravity, pH, leukocyte esterase, blood, nitrite, bilirubin, urobilinogen, protein, glucose

Question 23

What does the microscopic exam of urinalysis detect?

Answer 23

Red cells, white cells, casts, crystals

Question 24

What do cell casts in a UTI suggest?

Answer 24

kidney involvement

Question 25

How does the nitrite test in urinalysis work?

Answer 25

nitrate in diet converted to nitrite by most bacteria

must be in bladder 4 hrs to happen - can get false negative

Question 26

How does pyuria detection work in urinalysis?

Answer 26

generally leukocytes >5 WBC/hpf in true UTI
sterile pyuria can be in urine contamination, chronic interstitial nephritis, kidney stones, uroepithelial tumors, interstitial cystitis, rarely renal tuberculosis or inf like chlamydia

Question 27

What agars are used in urine cultures?

Answer 27

sheep blood - nonselective
MacConkey - isolates gram- and differentiates lactose fermenting from non fermenting
CNA - isolates gram+

Question 28

What CFU is suggestive of infection rather than contamination?

Answer 28

at least 10^5
some symptomatic women with pyuria will have inf with lower colony counts (still at least 10^2)
lower colony counts may represent true inf in those already being treated and men

Question 29

If a patient with a catheter is symptomatic, what colony counts define a UTI?

Answer 29

> 10^5 regardless of urinalysis results

>10^3 with evidence of pyuria

Question 30

How are urine specimens collected in children?

Answer 30

no clean catch

catheterization or suprapubic aspiration

Question 31

In children, what urine culture results indicate UTI?

Answer 31

symptoms PLUS pyuria or bacteriuria PLUS >10^4 bacteria

Question 32

How are imaging tests used in UTIs?

Answer 32

not indicated for cystitis
considered in early eval of pyelonephritis
Ultrasound or CT can see abscess, urolithiasis, anatomic complications

Question 33

What population should always receive imaging?

Answer 33

afebrile infants with UTI - renal and bladder ultrasonography
VCUG based on ultrasound results, if recurrent febrile UTIs, or hydronephrosis and scarring

Question 34

What are the generic principles of treating UTIs?

Answer 34

treat asymptomatic only in pregnant - reduces risk of symptomatic - or about to undergo urologic procedures
if pyelonephritis - antibiotic should have systemic distribution, not concentrate in urine (no nitrofurantoin)
no ampicillin alone for E coli