IC13: UTI

Question 1

Define Asymptomatic Bacteruria

Answer 1

Isolation of significant colony counts of bacteria in the urine (bacteriuria) from a person WITHOUT symptoms of a UTI (asymptomatic)

Question 2

Define UTI

Answer 2

Isolation of significant colony counts of bacteria in the urine from a person with urinary symptoms

Question 3

Screening and treatment of ASB is indicated for which populations?

Answer 3

1) Pregnant women

2) Patients going for urologic procedure in which mucosal bleeding/trauma is expected

Question 4

Patient is about to go have a urine catheter inserted. Should patient be screened for ASB?

Answer 4

No

Question 5

State the duration of treatment of ASB for ASB positive pregnant women and patient going for urologic procedure respectively.

Answer 5

Pregnant: 4-7 days

Urologic procedure: 24 hours (SAP)

Question 6

State and explain the host defence mechanisms that prevent UTI (total 4)

Answer 6

1) Micturition (increased urinary urgency)
o Stimulated by bacteria presence in bladder, leading to increased urgency and increased frequency of diuresis -> increased emptying of bladder

2) Antibacterial urine and prostatic secretions
o Contain enzymes that act against bacteria to prevent multiplication and causing infection

3) Anti-adherence mechanisms of bladder
o Presence of mucosal enzymes prevent adherence hence bacteria unable to invade urinary tract tissues and cause infections

4) Inflammatory response with polymorphonuclear leukocytes (PMNs) i.e phagocytosis by neutrophils -> prevent/ control spread

Question 7

What are the non-pharmacological measures to prevent UTI? (total 6)

Answer 7

1) Drink lots of fluid to flush the bacteria (6-8 glasses if no other health problems that require fluid restriction)

2) Urinate frequently and go when you first feel the urge. (prevents urine stasis which allow bacteria to grow)

3) Urinate shortly after sex. (flush away bacteria that might have entered your urethra during sex)

4) Wipe from front to back, especially after a bowel movement especially for women after using toilet

5) Wear cotton underwear and loose-fitting clothes so that air can keep the area dry. Avoid tight fitting jeans and nylon underwear, which trap moisture and can help bacteria grow.

6) For women, using a diaphragm or spermicide for birth control can lead to UTIs by increasing bacteria growth. If you have trouble with UTIs, consider modifying your birth control method. Unlubricated condoms or spermicidal condoms increase irritation, which may help bacteria grow.

Question 8

What are Non-Pharmacological measures for Catheter-associated UTI prevention? (total 5)

Answer 8

1) Avoid unnecessary catheter use

2) Use for minimal duration

3) Change long-term indwelling catheters before blockage is likely to occur

4) Use of closed system (use catheter and urine bag that comes as 1 set)

5) Ensure aseptic insertion technique

Question 9

Describe the routes of infection for UTI and state the likely pathogens for each route.

Answer 9

1) Ascending:
Colonic/ fecal flora colonise periurethral area/urethra and ascend to the bladder/kidney

Likely pathogens: Enteric Gram Negs (E. coli, Klebsiella, Proteus)

2) Hematogenous (Descending):
Pathogen at distant primary site (e.g heart, bone) enters the bloodstream and travels to urinary tract and cause infection

Pathogens: Others (e.g S. Aureus, mycobacterium tuberculosis) -> suspect this route when isolates are not E.coli, proteus or klebsiella

Question 10

What are the determining factors of UTI development?

Answer 10

1) Host defence mechanism

2) Virulence of pathogen

3) Inoculum size

Question 11

E coli has resistance to host defence mechanisms through ___?

Answer 11

presence of pili that are resistant to washout or removal by anti-adherence mechanisms

Question 12

What are the risk factors for UTI? (total 11)

Answer 12

1) Females > males

2) Sexual intercourse

3) Abnormalities of the urinary tract
* E.g. prostatic hypertrophy, kidney stones, urethral strictures (narrowing of urethra), vesicoureteral reflux [urine flows back from bladder into kidneys; usually due to malfunction of structural valves (increases risk of pyelonephritis as well)]

4) Neurologic dysfunctions -> increases urine retention
* E.g. stroke, diabetes, spinal cord injuries

5) Anti-cholinergic drugs
* E.g 1st gen antihistamines, atropine cause urinary retention

6) Catheterization and other mechanical instrumentation

7) Diabetes
* Neuropathy leading to urine retention or glycosuria facilitating bacteria growth

8) Pregnancy

9) Use of diaphragms & spermicides

10) Genetic association
* In women with +ve family history (1st degree female relatives e.g mother or sister with UTI)

11) Previous UTI

Question 13

What are the risk factors for catheter associated UTI? (total 6)

Answer 13

1) Duration of catheterisation

2) Colonisation of drainage bag, catheter and periurethral segment

3) DM

4) Female

5) Renal function impairment

6) Poor quality of catheter care, including insertion

Question 14

Explain the variation in prevalence of UTI with age and gender

Answer 14

Prevalence increases with age (increased age = increased likelihood of comorbidities related to urine obstruction and retention)

More prevalent in males from age 0-6mths (due to higher rate of structural and functional abnormalities of urinary tract)

More common in females from age 1- adulthood (shorter urethra and no protection from antimicrobial prostate secretions unlike men)

Prevelance equalises in elderly at ages > 65

Question 15

What are the symptoms of Cystitis? (5)

Answer 15

1) Dysuria (discomfort or burning sensation with urination)

2) Increased urgency, frequency

3) Nocturia

4) Suprapubic heaviness or pain

5) Gross hematuria (blood in urine that is visible)

Question 16

What are symptoms of pyelonephritis?

Answer 16

Systemic symptoms: Fever, rigors, headache, nausea, vomiting, and malaise

Urinary tract symptoms:
- Flank pain/ Costovertebral tenderness (positive renal punch),
- or abdominal pain

Question 17

What symptoms are present in cystitis that is the most unlikely to be present in catheter associated UTI?

Answer 17

Dysuria and increased urgency

Question 18

What are the symptoms of catheter associated UTI?

Answer 18

• New onset or worsening of fever, rigors, altered mental status, malaise, or lethargy with no other identified cause
• Flank pain
• Costovertebral angle tenderness (+ve renal punch)
• Acute hematuria (Blood in urine that is not visible)
• Pelvic discomfort

Question 19

What are the components of Urinanalysis (UFEME)?

Answer 19

1) WBC
2) RBC
3) WBC Casts
4) Microorganisms

Question 20

What are the components of the dipstick test?

Answer 20

1) Nitrite test
2) Leukocyte esterase test

Question 21

What component of UFEME may differentiate a patient with pyelonephritis from patient with cystitis?

Answer 21

Presence of WBC Casts (if present, may be pyelonephritis; only occur in upper urinary tract disease)

Question 22

What component of urine dipstick may help to differentiate a UTI caused by gram negative from gram positive?

Answer 22

Nitrite test (positive test = presence of gram negative)

Question 23

What does leukocyte esterase test detect?

Answer 23

Positive test detects esterase activity of leukocytes in urine. Correlates with significant pyuria.

Question 24

Urine culture is not required for which group of UTI patients?

Answer 24

Patients with uncomplicated cystitis

Question 25

What are some causes of negative nitrite test although UTI present?

Answer 25

1) Presence of Gram +ve
2) Pseudomonas
3) dilute urine
4) low urine pH
5) frequent voiding

Question 26

What are the likely pathogen for uncomplicated or community acquired UTI?

Answer 26

1) Escherichia coli (>85%)

2) Staphylococcus saprophyticus (5-15%)
* Common colonizer of urinary tract

3) Others: Gut Enterobacteriaceae
- Enterococcus faecalis
- Klebsiella pneumoniae
- Proteus spp

Question 27

What are the likely pathogen for complicated or healthcare associated UTI?

Answer 27

1) Escherichia coli (~50%)

2) Enterococci

3) Others:
- Enterococcus faecalis
-Klebsiella pneumoniae
-Proteus spp
- Pseudomonas Aeruginosa

**More drug resistant strains may also be present

Question 28

Describe the similarities and differences in bacteria prevalence between Uncomplicated and Complicated UTI

Answer 28

1) E. coli is predominant strain in both uncomplicated and complicated but complicated as higher % prevalence of other causative bacteria

2) Staphylococcus saprophyticus may be present in uncomplicated but not in complicated UTI

3) Pseudomonas present in complicated UTI but not uncomplicated

Question 29

What microorganisms when present in urine culture may be considered as contaminants or a sign that there may be another site of infection?

Answer 29

Yeast, candida and S. Aureus

(Yeast and candida more likely contaminant; S . Aureus more likely other site of infection)

Question 30

What are the first line empiric treatment for simple UTI in women? Include dose and duration

Answer 30

1) Co-trimoxazole 960mg BD for 3 days

2) Nitrofurantoin 50mg QDS for 5 days

3) Fosfomycin 3g single dose

Question 31

What are the alternative therapies for women with simple UTI?

Answer 31

PO beta lactams (5-7 day tx)
1) PO Cefuroxime 250mg BD
2) PO Augmentin 625mg BD
3) PO Cephalexin 250-500mg QDS(?)

PO FQs (3 day tx)
1) Ciprofloxacin 250mg BD
2) Levofloxacin 250mg daily

Question 32

State how the treatment regimen for complicated cystitis differs from simple cystitis.

Answer 32

Duration of treatment extend to 7-14 days

Fosfomycin dose 3g EOD, 3 doses total

Question 33

State empiric therapy for community acquired pyelonephritis in women who still can eat

Answer 33

PO FQs
- Ciprofloxacin 500mg BD for 7 days
- Levofloxacin 750mg daily for 5 days

PO Bactrim 960mg BD for 10-14 days

PO beta-lactams for 10-14 days
- Cefuroxime 250-500mg BD
- Augmentin 625mg TDS
- Cephalexin 500mg QDS (?)

Question 34

State empiric therapy for community acquired pyelonephritis in women who need IV treatment

Answer 34

1) IV Cipro 400mg BD x 7 days OR
2) IV Cefazolin 1g q8H x 10-14 days OR
3) IV Augmentin 1.2g q8h x 10-14d

AND/OR
4) IV/IM Gentamicin 5mg/kg (cover potential ESBL)

Durations are same as for PO tx

Question 35

What are the antibiotics of choice for treatment of UTI with concerns for prostatitis or pyelonephritis in men? State the respective durations.

Answer 35

Ciprofloxacin 500mg BD

Co-trimoxazole 960mg BD

Pyelo: 10-14 days

Confirmed prostatitis: 6 weeks

Question 36

What is the empric therapy for Healthcare-associated pyelonephritis? State the pathogens that need to be considered in these infections and treatment duration

Answer 36

Pseudomonas and ESBLs

Empiric therapy choices (7-14 days tx):

Broad spectrum beta-lactam +/-Aminoglycoside (All IV):
1) IV Cefepime* 2g q12h +/- IV Amikacin 15mg/kg/d
OR
2) IV Imipenem 500mg q6h or IV Meropenem 1g q8h

OR
PO FQs* + IV Aminoglycoside:
1) PO Levofloxacin 750mg (oral option for less sick patients; IV can also use)
2) PO Ciprofloxacin 500mg bid (oral option for less sick patients; IV can also use)

• Need to add on AG as they are not good at covering ESBLs

Question 37

Define Nosocomial UTI

Answer 37

onset of UTI > 48h post admission

Question 38

Define healthcare associated UTI

Answer 38

Patients who have been hospitalized or underwent invasive urological procedures in the last 6 months, has an indwelling urine catheter etc

Question 39

Define Catheter-associated UTI

Answer 39

Presence of symptoms or signs compatible with UTI with no other identified source of infection along with 10^3 cfu/mL of ≥1 bacterial species in a single catheter urine specimen in patients with indwelling urethral, indwelling suprapubic, or intermittent catheterization or in a midstream voided urine specimen from a patient whose catheter has been removed within the previous 48h

Question 40

State the possible empiric regimens for severe catheter associated UTI (include duration)

Answer 40

1) IV Imipenem 500mg q6H or IV Meropenem 1g q8h

2) IV Cefepime 2g q12H +/- IV Amikacin 15mg/kg (1 dose)

Duration: 7 days for those with prompt resolution of symptoms (no fever within 72 hours). 10-14 days for delayed response.

(similar to healthcare associated pyelo, just w/o FQs for severe)

Question 41

Which antibiotics are to be avoided in pregnancy? (state the trimesters if relevant)

Answer 41

1) Avoid ciprofloxacin (potential arthropathies)

2) Avoid co-trimoxazole in first and third trimester
* Avoid in first trimester as folate antagonism of TMP can cause neural tube defects
* Avoid use close to term in third trimester due to theoretical risk of kernicterus (hyperbilirubinemia) in newborns from competitive binding between bilirubin and sulfonamides to plasma albumin
* Concern for foetus being G6PD-deficient

3) Nitrofurantoin avoided at term (38-42 weeks)
* Concern for foetus being G6PD-deficient

4) Aminoglycosides are used with caution
* 8th cranial nerve toxicity in the fetus reported with older aminoglycosides –kanamycin, streptomycin; not reported for newer aminoglycosides so far

5) Fosfomycin can be used but do not use single dose therapy (use the 3 day therapy)

Question 42

Which class of antibiotics is safe for use in pregnancy for UTI?

Answer 42

Beta-lactams

Question 43

What are the respective durations of tx for pregnant women with cystitis and pyelonephritis?

Answer 43

Cystitis: 4-7days
Pyelo: 14 days

Question 44

What are the adjunctive therapies for UTI? (3 total)

Answer 44

Paracetamol or NSAIDs (Pain and fever)

Drink water (Vomiting)

Phenazopyridine (Urogesic; for dysuria symptoms) Dosing: 100-200mg TDS. Don’t use in G6PD deficiency.
ADRs; N/v, orange discolouration of urine and stool

Question 45

Monitoring parameters for UTI

Answer 45

1) Resolution of signs & symptoms
- Improvement or resolution by 24 to 72 hrs after initiation of effective antibiotics
- If the patient fails to respond clinically within 2 to 3 days or has persistently positive blood or urine cultures, further investigation is needed to exclude bacterial resistance, possible obstruction, renal abscess, or some other disease process

2) Bacteriological clearance
- Repeat culture is not required for patients who responded
- Culture to document clearance of infection for
* Pregnant women

3) Absence of adverse drug reactions and allergies

Question 46

What are the possible reasons for low WBC count (no pyuria) but patient still has UTI?

Answer 46

1) Neutropenic patient
2) Dilute urine

Question 47

State the possible empiric regimens for mild catheter associated UTI (include duration)

Answer 47

1) PO/ IV Levofloxacin 750mg x 5 day (for mild CA-UTI)

2) PO Co-trimoxazole 960mg bid x 3 day (For women ≤65 years with CA-UTI without upper urinary tract symptoms after an indwelling catheter has been removed)

Question 48

What is the non-pharmacological management to be considered when patient has catheter-UTI?

Answer 48

o Removal of catheter should always be considered
- If an indwelling catheter has been in place for >2 weeks at the onset of CA-UTI and is still indicated, the catheter should be replaced to hasten resolution of symptoms and to reduce the risk of subsequent CA bacteriuria and CA-UTI.