Urinary Tract Infections

Question 1

Classification of UTIs?

Answer 1

1. Asymptomatic bacteriuria
2. Symptomatic lower UTI
   e.g. Acute cystitis
3. Upper UTI
   e.g. Acute pyelonephritis

Question 2

Epidemiology of UTI?

Answer 2

UTI is more common in females.
- (1-2% of young non-pregnant women)
- 40% of females will have a symptomatic UTI in their life time.

Question 3

UTI in men?

Answer 3

prevalence is 0.04%

Question 4

Incidence of UTIs?

Answer 4

• Incidence of UTI increases in old age
• 10% of men & 20% of women

Question 5

Routes of infection?

Answer 5

1. ascending infection
2. hematogenous spread
3. lymphogenous spread
4. direct extension from other organs

Question 6

Most common route of infection in UTIs?

Answer 6

Ascending infection from the urethra is the most common route
Note: Pyelonephritis most commonly results from ascent of infection up the ureter.

Question 7

Hematogenous cause of UTIs?

Answer 7

hematogenous spread to the urinary tract is uncommon, the exceptions being:
1. tuberculosis
2. cortical renal abscesses

Question 8

Lymphogenous spread?

Answer 8

is rare

Question 9

Direct extension from other organs?

Answer 9

Direct extension from other organs may occur, especially from
1. intra-peritoneal abscesses in inflammatory bowel disease
2. pelvic inflammatory disease

Question 10

Risk factors for UTIs in females?

Answer 10

1. sexual activity
   - use of spermicidal, diaphragm
2. Pregnancy.
3. Estrogen deficiency (Post menopausal )
4. short urethra

Question 11

Risk factors for UTIs in males?

Answer 11

1. lack of circumcision,
2. prostatic hypertrophy,

Question 12

Risk factors for UTIs in both sexes?

Answer 12

1. Obstruction,
2. Vesicoureteric reflux,
3. Instrumentation, & catheterization
4. Neurogenic disorders that impairs bladder, emptying
5. Diabetes (increase risk of complications and fungal infections)

Question 13

How is obstruction a risk factor for UTIs?

Answer 13

any microorganism that enter the bladder is washed out during voiding therefore when outflow is obstructed urine remains in bladder — medium for microbial growth

Question 14

How is increased pressure in the bladder a risk factor for UTIs?

Answer 14

Increase pressure in bladder compresses vessels in bladder wall
- decrease in the mucosal defense

Question 15

Anatomical obstructions that are risk factors for UTIs?

Answer 15

1. Stones
2. Prostatic hyperplasia
3. Pregnancy
4. Malformation of ureterovesical junction

Question 16

Functional obstructions that are risk factors for UTIs?

Answer 16

1. Neurogenic bladder
2. Infrequent voiding
3. Constipation

Question 17

How are catheter induced infections risk factors for UTIs?

Answer 17

1. Provide a means for entry of microorganisms into the urinary tract
2. Bacteria adhere to surface of catheter & initiate the growth of biofilm that covers the surface of catheter.
3. Biofilm protects the bacteria from antibiotics

Question 18

Causes of uncomplicated lower UTIs?

Answer 18

1. Escherichia Coli - gram negative bacillus
2. Staphylococcus saprophyticus - gram positive coccus

Question 19

Causes of complicated UTIs?

Answer 19

1. Proteas mirabiris
2. Klebsiella species
3. Enterobacter species
4. Pseudomonas Eurogenosa
   - mainly gram negative rods
5. Staph aurius (gram positive cocci)

Question 20

What is the pathogenesis of UTIs?

Answer 20

Pathogenesis of UTI involves interaction of host with agent leading to let down of host defences against virulence of infectious agents

Question 21

Components of the bladder that act as host defences in preventing UTIs?

Answer 21

Urinary bladder is usually resistant to bacterial colonization
1. Washout Phenomenon
- Bacteria removed during voiding
2. Protective mucin layer
- Protects against bacterial invasion
3. Immune mechanisms
- secretory immunoglobulin(lgA), PMN cells

Question 22

What other urinary host defences prevent UTIs?

Answer 22

1. Normal flora in periurethral area in women
2. prostatic secretions in males

Question 23

What kind of E.coli produces UTI?

Answer 23

Only those strains of E-coli with increased ability to adhere to epithelial cells to produce UTI
- Most E.coli causing UTI belong to O,K and H serotypes.

Question 24

Describe the pathogen virulence that allows E. coli to produce UTIs?

Answer 24

Uropathogenic E.coli have
1. fimbria /Pilli - for adherence
2. Secrete hemolysin & aerobactin -resist serum bactericidal action

Question 25

Pathogenesis of Uropathogenic E.coli?

Answer 25

1. Periuretheral area & urethra are colonised by bacteria. 2. Bacteria enter bladder in susceptible host. 3. Adherence properties enable pathogens to colonise bladder 4. Pathogens attach to uroepithelial mucosa, secretion of cytokines recruitment of PMNs inflammation. 5. Pathogens may ascend through ureter to kidney causing pyelonephritis

Question 26

Clinical presentations of UTIs?

Answer 26

1. asymptomatic bacteriuria 2. cystitis 3. acute pyelonephritis

Question 27

Features of asymptomatic bacteriuria?

Answer 27

1. Common in females & elderly. 2. 25% develop symptomatic UTI 3. 25% clear spontaneously. 4. Spontaneous cure & reinfection are common

Question 28

Features of cystitis?

Answer 28

1. Frequency, dysuria , urgency. 2. Suprapubic discomfort +/- tenderness. 3. Fever is often absent 4. Ocasionally urine is cloudy and foul smelling

Question 29

Features of acute pyelonephritis?

Answer 29

1. Fever, abdominal pain, vomiting. 2. Dysuria ,frequency, flank or loin pain. 3. Flank or loin tenderness. 4. In elderly: symptoms are often atypical. 5. Bacteremia is common.

Question 30

Describe the change in renal anatomy and physiology of pregnant women?

Answer 30

1. Dilation of calyces, pelvis and ureters. 2. Reduction in peristaltic activity of ureters - thought to be muscle relaxing effect of progesterone - mechanical obstruction from enlarge uterus

Question 31

Complications of UTI in pregnant women?

Answer 31

1. Persistent bacteriurea - UTI during pregnancy may be the result of preexisting asymptomatic bacteuria therefore Urine culture is recommended at first prenatal visit 2. Acute or chronic pyelonephritis 3. premature delivery. 4. low birth weight infant. 5. Increased newborn mortality

Question 32

Describe UTIs in the elderly?

Answer 32

- Second most common cause of infection after respiratory tract infection - Vague symptoms –anorexia,fatigue and weakness - Difficult to interpret because elderly people without UTI also commonly experience urgency, frequency and incontinence.

Question 33

Investigations and making a diagnosis of UTIs?

Answer 33

1. Urine microscopy: -WBCs, RBCs 2. Urine dipstick - Nitrites,Leukocytes 3. more markers of infection 4. Urine culture & sensitivity to antibiotics 5. Significant bacteriuria= 100000 cfu/ml 6. symptoms: 1 +ve culture = infection

Question 34

Diagnosing UTIs?

Answer 34

1. Symptoms: 10000 cfu/ml = propable infection 2. Asymptomatic: 2 +ve urine cultures = infection 3. False negative : antibiotics, antiseptics, diuresis. 4. FBC 5. BLOOD CULTURE

Question 35

What kind of sample is needed to test for UTIs?

Answer 35

to confirm diagnosis always send a mid-stream urine sample for culture, collected before antibiotics

Question 36

Urine dipstick test results that correspond to UTIs?

Answer 36

Positive dipstick a urine dipstick test with positive nitrites makes UTI more likely in men (PPV 96%) Negative dipstick Negative for both nitrite and leucocyte makes UTI less likely, especially if symptoms are mild

Question 37

Investigations used to identify contributing factors like obstruction?

Answer 37

1. X-ray 2. Ultrasonography 3. CT scan 4. Renal scans

Question 38

Management of lower UTI in non-pregnant women?

Answer 38

dependent on local guidelines 1. Trimethoprim 2. Nitrofurantoin 3. quinolones

Question 39

Management of lower UTI in pregnant women?

Answer 39

1. send urine culture 2. Nitrofurantoin - avoid near term of pregnancy 3. Amoxicillin or cefalexin for second line - Avoid Trimethoprim and quinolones because they are teratogenic 4. Treat asymptomatic bacteriuria in pregnancy - do urine cultures routinely

Question 40

UTI management in men?

Answer 40

Immediate abx therapy for 7 days 1. Start with Trimethoprim (dependent on local sensitivities) or Nitrofurantoin 2. Quinolones 3. Do not treat asymptomatic bacteriuria in catheterised patients

Question 41

Upper UTI treatment for acute pyelonephritis?

Answer 41

1. Broad-spectrum antibiotics, cephalosporins or quinolones. 2. Manage any complications like Urosepsis accordingly 3. Refer to urology for suspected recurrent UTIs for suspected urinary tract abnormality corrections