Urinary Tract Infections Flashcards
1
Q
Define urinary tract infections (UTI)
A
the presence of microorganisms in the urinary tract, NOT due to contamination
- broad spectrum of clinical entities
- self limiting asymptomatic bacteriuria, cystitis, pyelonephritis, UTI with bacteremia, sepsis or death
2
Q
What is included in upper UTI?
A
Pyelonephritis
3
Q
What is included in lower UTI?
A
Cystitis
urethritis
prostatitis
epididymitis
4
Q
For pts of age 0-6months, why are UTI more common in males ?
A
approx 1% prevalence
- higher rate in males due to the higher rate of functional and structural abnormalities in boys
5
Q
From the age of 65 onwards, what is the prevalence of UTI?
A
Equal
more co-morbidities relating to retention/obstruction of urine (i.e. BPH)
- more urine/bowel incontinence in elderly (may be due to stroke, muscular dysfunction)
- use of urinary catheter more common in elderly regardless of gender
6
Q
Describe the pathogenesis, risk factors and expected organisms of ascending UTI
A
• Colonic/ fecal flora colonise periurethra area/ urethra
–> ascend to bladder and kidney
• Higher risk in females (shorter urethra), use of spermicides, diaphragms as contraceptives
• Eg of organisms (enterobacteria) – E. coli, Klebsiella, Proteus
7
Q
Describe the pathogenesis and expected organisms of descending (hematogenous route) UTI
A
- Organism at distant primary site (eg heart valve, bone) –> bloodstream (bacteremia) –> urinary tract –> UTI
- Eg of organisms – Staphylococcus aureus, Mycobacterium tuberculosis
8
Q
When will the hematogenous route be suspected for UTI?
A
Hematogenous route suspected when non-gut bacteria are cultured using urine
- usually will scan the pt for bacteremia and find possible sites of primary infection
9
Q
Factors determining the development of UTI?
A
- Competency of the natural host defense mechanisms
- Size of the inoculums
- Virulence/pathogenicity of the microorganism
10
Q
What are some natural host defense mechanisms in UTI?
A
- Bacteria in bladder stimulates micturition with increased diuresis –> emptying of bladder
- Antibacterial properties of urine & prostatic secretion
- Anti-adherence mechanisms of bladder (prevent bacterial attachment to the bladder)
- Inflammatory response with polymorphonuclear leukocytes (PMNs) –> phagocytosis –> prevent/control spread
11
Q
What affects the size of inoculum in a pt with UTI?
A
incur with obstruction/ urinary retention
12
Q
What are examples of virulence/pathogenicity of organisms in UTI?
A
• eg bacteria with pili (eg E. coli) resistant to washout or removal by anti-adherence mechanisms of bladder
13
Q
What are some risk factors for UTI ?
A
- Females > males
- Sexual intercourse
- Abnormalities of the urinary tract eg prostatic hypertrophy, kidney stones, urethral strictures, vesicoureteral reflux
- Neurologic dysfunctions eg stroke, diabetes, spinal cord injuries
- Anti-cholinergic drugs
- Catheterization and other mechanical instrumentation
- Diabetes
- Pregnancy
- Use of diaphragms & spermicides
- Genetic association (positive family history)
- Previous UTI
14
Q
Why do females have a higher risk of UTI?
A
shorter urethra = easier ascent for bacteria from urethra to bladder
15
Q
Why is sexual intercourse a risk factor for UTI?
A
increased colonization of bacteria at vaginal area
- may change vaginal flora
- can increase ascent of bacteria from urethra to bladder
16
Q
Why are urinary tract abnormalities a risk factor for UTI?
A
structural abnormalities leading to urinary retention/obstruction
- strictures –> narrowing of lumen
- reflux –> backflow due to malfunctions in valves that prevent such backflow –> bacteria can ascend from bladder to kidneys
17
Q
Why are neurologic dysfunctions a risk factor for UTI?
A
pts are more likely to have urinary retention
18
Q
Why are anti-cholinergic drugs a risk factor for UTI?
A
key side effect is urinary retention (1st gen anti-hist, atropine) –> cannot remove bacteria in urine
19
Q
Why is catherization and other mechanical instrument a risk factor for UTI?
A
includes laproscopy tube
- tubes can habour growth of bacteria (formation of biofilm possible) –> increase in inoculum and access to urinary tract
20
Q
Why is diabetes a risk factor for UTI?
A
can have some neuropathy + high urine sugar content promote bacteria growth
21
Q
Why is the use of diaphragms and spermicides a risk factor for UTI?
A
exact reason not known, perhaps due to alteration in flora in peri-urethral/vaginal area –> more colonization and increase in size of inoculum
22
Q
What do we refer to when we say genetic association is a risk factor for UTI?
A
specifically 1st degree female relatives
23
Q
What are some non-pharms to prevent UTIs?
A
- Drink lots of fluid to flush the bacteria. Go for 6-8 glasses a day. (if feasible)
- Urinate frequently and go when you first feel the urge.
- Urinate shortly after sex. This can flush away bacteria that might have entered your urethra during sex.
- After using the toilet, always wipe from front to back, especially after a bowel movement.
- Wear cotton underwear and loose-fitting clothes so that air can keep the area dry.
- For women, using a diaphragm or spermicide for birth control can lead to UTIs. Unlubricated condoms or spermicidal condoms increase irritation, which may help bacteria grow.
24
Q
Define complicated UTI
A
- Complicated: UTI associated with conditions that increase the potential for serious outcomes, risk for therapy failure
- Eg UTIs in men, children and pregnant women
- Presence of complicating factors
25
What are some complicating factors for UTI?
functional and structural abnormalities of urinary tract, genitourinary instrumentation, diabetes mellitus, immunocompromised host
26
How can we classify an uncomplicated UTI?
No complicating factors
| • Usually in healthy premenopausal, non-pregnant women with no history suggestive of an abnormal urinary tract
27
How do we diagnose uncomplicated UTI?
Infection usually suspected based on typical symptoms
| - Urinalysis and culture not routinely needed for cystitis but recommended for pyelonephritis
28
How do we diagnose Complicated UTI?
Typical symptoms or atypical symptoms (catherization, altered mental status, impaired sensation)
- Urinalysis and culture indicated
29
What can we expect with regards to antimicrobial resistance in uncomplicated UTI?
Common but generally predictable
30
Does Antimicrobial resistance alone warrant the designation complicated UTI?
No
31
What can we expect with regards to antimicrobial resistance in complicated UTI?
Multidrug resistance common and less predictable
| - FQ resistance common
32
Recall the 4 steps of systematic approach to antimicrobial therapy
1. Confirm presence of infection (indication for antibiotics)
• Risk factors for infections
• Subjective evidence
• Objective evidence
• What is the (possible) site of infection
2. Identification of pathogens
• What is the (likely) pathogen
• Any microbiological test sent or results available
3. Selection of antimicrobial and regimen
• Empiric, definitive or prophylaxis
• Consider organism, host and drug factors
• Decide on choice of agent, route, dosing and duration of treatment
4. Monitor response
• Therapeutic response
• Adverse drug reactions
33
What are some Subjectives for UTI (cystitis)?
• lower urinary tract infections (cystitis)
| - dysuria, urgency, frequency, nocturia, suprapubic heaviness or pain; gross hematuria
34
What are some Subjectives for UTI (pyelonephritis)?
• upper urinary tract infections (pyelonephritis)
- fever, rigors, headache, nausea, vomiting and malaise, flank pain, costovertebral tenderness (renal punch), or abdominal pain
35
What are some things to note when evaluating Subjective evidence for UTI?
- Sx may not clearly point towards pyelonephritis/cystitis and there can be other reasons for these sx presentations as well
- Esp When UTI occurs frequently for elderly, they frequently do not experience urinary sx but can present w altered mental status, i.e. being more drowsy, less alert, change in eating habits and general GIT sx
36
What are some Objectives for UTI?
Urine sent for urinalysis (i.e. UFEME, chemical analysis) and culture
37
What are the 3 methods of urine collection for UTI?
1) Midstream clean-catch
2) Catheterization
3) Suprapubic bladder aspiration
38
How can we perform Midstream Clean-catch properly?
discard the 1st 20-30mL, collects the next 20-30mL)
| - 1st 20-30mL urine possibly contaminated w urethral colonizers --> discard
39
What is a key difference between pyelonephritis and cystitis with regards to objective evidence?
Pyelonephritis usually has more objective evidence of systemic infections i.e. higher temp, increased total WBCs, neutrophils, increased CRP, procalcitonin
40
What are the parameters covered in UFEME (Urine Formed Elements and Microscopic Examination)
WBCs
RBCs
Microbes
WBC casts
41
How can we rationalize WBCs in UFEME?
* > 10 WBCs/mm3 = pyuria
* Signifies presence of inflammation, may or may not be due to infection.
* In a symptomatic patient, pyuria correlates with significant bacteriuria
* Absence of pyuria = unlikely UTI
42
How can we rationalize RBCs in UFEME?
• Presence (microscopic >5/ HPF or gross) = hematuria
• Frequently occurs in UTI but non-specific i.e. if menses or other reasons leading to hemorrhage of urine tract
- hematuria can be due to trauma (i.e. when there is catheterization, stones, malignancy)
43
How can we rationalize WBC casts in UFEME?
* masses of cells and proteins that form in renal tubules (in kidneys)
* indicate upper tract infection / disease
44
What are the Microbial test(s) done in UFEME?
• Identify bacteria or yeast using Gram-stain
45
What are the chemical analysis tests for UTI?
Dipsticks
- Nitrite
- Leukocyte esterase
46
How can we rationalize the nitrite dipstick test in chemical analysis?
- Positive test detects presence of Gram-negative bacteria
- Requires at least 10^5 bacteria/ml
- Only Gram-negative organisms reduces nitrate to nitrite
- False-negative results due to presence of Gram-positive organisims and P. aeruginosa, low urinary pH, frequent voiding and dilute urine.
47
How can we rationalize the leukocyte esterase dipstick test in chemical analysis?
- Positive test detects esterase activity of leukocytes in urine
- Correlates with significant pyuria (>10 WBCs/mm3)
48
When should we NOT obtain urine cultures?
NOT necessary in uncomplicated cystitis
- as it has been found that positive urinary dipsticks are very predictive of uncomplicated UTI --> easily treated --> no need to know identity of bacteria
- can just give general empirical abx and pt will respond
49
When are pre-treatment cultures necessary?
* Pregnant women
* Recurrent UTI (relapse within 2 weeks or frequent)
* Pyelonephritis
* Catheter-associated UTI
* All men with UTI
50
What is the likely pathogen for uncomplicated or community acquired UTIs?
- Escherichia coli (>85%)
- Staphylococcus saprophyticus (5-15%) --> common urinary tract colonizer
- Others: Enterococcus faecalis, Klebsiella pneumoniae, Proteus spp
*gut enterobacteriacae (commonly causing UTI via ascending route) with E coli being the most common
51
What is the likely pathogen for complicated or healthcare associated UTIs?
- E. coli (around 50%)
- Enterococci
- Proteus spp, Klebsiella spp, Enterobacter spp, P. aeruginosa
* additionally, ESBL/MDR strains of bacteria may be present, i.e. ESBL E Coli, proteus, klebsiella etc...
52
What are the healthcare associated factors?
```
Hospitalization in the last 90 days
Current hospitalization ≥ 2 days
Residence in nursing home
Antimicrobial use in the last 90 days
Home infusion therapy
Chronic dialysis
```
53
What are some other pathogens that can cause UTI?
- S. aureus – commonly due to bacteremia; consider other primary site of infections
- Yeast or Candida – possible contaminant; consider other sites of infection
54
When there is a positive urine culture. is there a need to treat UTI?
Yes if the pt is symptomatic
No if asymptomatic (except for 1. pregnant women 2. pts undergoing invasive urologic procedures with mucosal trauma e.g. TURP, cystoscopy with biopsy)
55
How are prophylactic abx given for surgery in the context of UTI?
Obtain culture then start antibiotics based on culture & sensitivity 12-24 hrs before procedure
56
What are the 1st line treatment options for EMPIRIC therapy for uncomplicated Cystitis in women (community acquired)?
* PO co-trimoxazole 800/160 mg bid x 3d or
* PO nitrofurantoin 50 mg qid x 5d
* PO fosfomycin 3 g single dose
57
What are the alternative treatment options for EMPIRIC therapy for uncomplicated Cystitis in women (community acquired)?
PO beta-lactams x 5-7 days:
• PO cefuroxime 250 mg bid
• PO cephalexin 500 mg bid
• PO amoxicillin-clavulanate 625 mg bid
PO fluoroquinolones x 3 days:
• PO ciprofloxacin 250 mg bid
• PO levofloxacin 250 mg daily
58
What are the changes in treatment options for EMPIRIC therapy for COMplicated Cystitis in women (community acquired)?
Treat for longer duration eg 7 to 14 days
7 - 14 days for co-trimoxazole
10 - 14 days for beta lactams
- Fosfomycin dose for complicated cystitis: PO 3 g EOD x 3 doses
*EOD - every other day
59
What are the Empiric Antibiotics for Community-acquired Pyelonephritis in women
PO fluoroquinolones
• PO ciprofloxacin 500 mg twice daily x 7 days or
• PO levofloxacin 750 mg daily x 5 days or
PO co-trimoxazole 160/800 mg twice daily x 14 days or
PO Beta-lactam x 10-14 days
• PO cephalexin 500 mg bid
• PO amoxicillin-clavulanate 625 mg tds
60
What are the Empiric Antibiotics for Community-acquired Pyelonephritis in women who are severely ill who require hospitalization/unable to take oral drugs?
- i.e. N/V
- [IV ciprofloxacin 400mg bid or IV cefazolin 1g q8h or IV amoxi-clav 1.2g q8h] and/or [IV/IM gentamicin 5mg/kg]
61
What is something to note when deciding on duration of abx after culture results return?
We count only the duration of active abx --> esp when urine culture results come back and we need to switch to new abx i.e. abx change to cipro despite pt being on co-trimox for 6days --> pt must finish 7 days of cipro now
62
Empiric Antibiotics for community-acquired UTI in Men (Cystitis without concern for prostatitis)
Use regimen as per complicated cystitis in women (treat for longer duration)
63
Empiric Antibiotics for community-acquired UTI in Men (Cystitis with concern for prostatitis or Pyelonephritis)
- PO ciprofloxacin 500mg twice daily or
- PO co-trimoxazole 800/160 mg twice-daily
- Treat for 10-14 days, will need longer duration if prostatitis is confirmed (6 weeks)
64
What are the s/sx of prostatitis?
- localized pain
- scrotal pain
- pain on ejaculation
- voiding difficulties
- such pts usually sent to urologists for more detailed checks
65
How can we detect nosocomial/healthcare associated pyelonephritis?
* Nosocomial – onset of UTI >48h post admission
* Healthcare associated - patients who have been hospitalized or underwent invasive urological procedures in the last 6 months, has an indwelling urine catheter, etc
*catheters are the most common cause of nosocomial UTI
66
What are the additional organisms that we have to cover in empiric therapy for nosocomial/healthcare associated pyelonephritis?
The possibility of Pseudomonas aeruginosa and other resistant bacteria (eg ESBL producing E coli and
Klebsiella) should be considered and broad-spectrum B-lactam may be used for empiric therapy.
67
Empiric Antibiotics for Nosocomial/ Healthcare associated Pyelonephritis
* IV cefepime 2g q12h +/- IV amikacin 15mg/kg/d or
* IV imipenem 500mg q6h or IV meropenem 1g q8h
* PO levofloxacin 750mg (for less sick patients)
* PO ciprofloxacin 500mg bid (for less sick patients)
* Duration of treatment is 7-14 days (7 if pt responds well)
68
How can we define catheter associated UTI (CA-UTI)?
• Presence of symptoms or signs compatible with UTI with no other identified source
- 10^3 cfu/mL of ≥1 bacterial species in a single catheter urine specimen
- catheterization
- midstream catch from a patient whose catheter has been removed within the previous 48 h
69
What are the risk factors for CA-UTI?
* Duration of catheterisation (KEY)
* Colonisation of drainage bag, catheter and periurethral segment
* DM
* Female
* Renal function impairment
* Poor quality of catheter care, including insertion
70
What are the causative organisms of CA-UTI?
* Short-term catheterisation (<7 days) – 85% single organisms – E coli, klebsiella
* Long-term (>28 days) – 95% polymicrobial (2-3 organisms) - E coli, klebsiella, pseudomonas
71
What are the morbidity and mortality characteristics relating to CA-UTI?
* Symptomatic manifestation uncommon
* Studies in long-term care facilities showed <10% febrile episodes due to UTI
* Usually low-risk or not associated with excess mortality
72
Is treatment of asymptomatic CA-UTI recommended?
• Treatment of asymptomatic bacteriuria not recommended except prior to traumatic urological procedures
73
How can we treat CA-UTI (non-pharms)?
* 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
74
What are some symptoms of CA-UTI?
```
New onset or worsening of fever
rigors
altered mental status
malaise, or lethargy with no other identified cause
flank pain
costovertebral angle tenderness
acute hematuria
pelvic discomfort.
```
75
How should we treat a patient with CA-UTI that is stable with a low grade fever?
Consider observation rather than immediate antibiotics therapy
76
What do we have to do before administering abx for a pt with CA-UTI?
Urine (+/- blood) culture must be taken before antibiotics is given
*Since CA-UTI likely to have resistant organisms
77
Empiric abx options for CA-UTI?
* IV imipenem 500mg q6H or IV meropenem 1g q8h
* IV cefepime 2g q12H +/- IV amikacin 15mg/kg (1 dose)
* PO/ IV levofloxacin 750mg x 5d (for mild CA-UTI)
* PO Co-trimoxazole 960mg bid x 3d (for women ≤65 years with CA-UTI without upper urinary tract symptoms after an indwelling catheter has been removed)
78
What is the usual duration of tx for CA-UTI?
• Duration of treatment: usually 7 days in those with prompt resolution of symptoms (i.e. deferverse in 72 hrs)
- 10–14 days of treatment for those with a delayed response
79
How can we prevent CA-UTI?
* Avoid unnecessary catheter use (i.e. do trial of catheter for pts)
* Use for minimal duration
* Long-term indwelling catheters changed before blockage is likely to occur
* Use of closed system
* Ensure aseptic insertion technique
80
What are 3 kinds of abx usage not recommended for CA-UTI?
* Topical antiseptic or antibiotics
* Prophylactic antibiotics and antiseptic
* Chronic suppressive antibiotics
81
What are some abx to avoid in pregnancy?
FQs
Co-trimoxazole (1st and 3rd trimester)
Nitrofurantoin (3rd trimester)
AGs (caution)
82
What is the usual treatment for pregnant pts with UTI?
Beta lactams (1st line)
• Choice of antibiotics based on cultures
• Treat for 7 days for asypmtomatic bacteriuria or cystitis
• Treat for 14 days for pyelonephritis
83
Cephalexin
• Normal dose, frequency and duration for different
classification of UTIs
• Patient counseling points
• Monitoring parameters (for common side effects)
- Cystitis: PO 500mg bd x 3-7d
| - Pyelonephritis: PO 500mg-1g bd x 14d
84
Cephalexin
| • Normal dose, frequency and duration for different classification of UTIs
- Cystitis: PO 500mg bd x 3-7d
- Pyelonephritis: PO 500mg-1g bd x 14d
- Some refs quote BD dosing. but in practice, it is given QDS --> 250-500mg q6h
- BD dosing ok for uncomplicated cystitis (easy to tx infection)
85
Cephalexin
| • Patient counseling points
Take without regards to food, if GI discomfort, take with food.
86
Cephalexin
| • Contraindication/Precaution/pregnancy/ADR
<10% cross-sensitivity for penicillin allergy (avoid if anaphylaxis).
Generally safe in pregnancy
ADR: GI
87
Co-trimoxazole
| • Normal dose, frequency and duration for different classification of UTIs
- Cystitis, women: PO 960mg bd x 3d
- Cystitis, men: PO 960mg bd x 7-14d
- Pyelonephritis: PO 960mg bd x14d
*SMZ 800mg/ TMP 160mg
88
Co-trimoxazole
| • Patient counseling points
N/V (take after food), photosensitivity, adequate hydration to prevent crystalluria,
Discontinue at first sign of rash.
89
Co-trimoxazole
| • Contraindication/Precaution/pregnancy/ADR
ADR: nausea, vomiting, myelosuppression, SJS, hyperkalemia, hepatotoxicity, photosensitivity
Avoid in sulpha allergy, G6PD def, 1st & 3rd trimester pregnancy, CrCl < 15ml/min, folate deficiency.
90
Ciprofloxacin
| • Normal dose, frequency and duration for different classification of UTIs
- Cystitis, women: PO 250mg bd x 3d
- Cystitis, men: PO 500mg bd x 7-14d
- Pyelonephritis: PO 500mg bd x 7-14d (7d in women)
91
Ciprofloxacin
| • Patient counseling points
GI upset (take w food). Administration apart from Ca, Fe.
CNS (headache, dizziness), photosensitivity. Tendon inflammation (discontinue at first sign of pain, esp in elderly).
92
Ciprofloxacin
| • Contraindication/Precaution/pregnancy/ADR
Avoid in pregnancy, children, patient with altered cardiac conduction
Caution in pt at risk of seizures.
ADR: tendon inflammation, hypo/hyperglycemia, photosensitivity, QTc prolongation
93
Nitrofurantoin
| • Normal dose, frequency and duration for different classification of UTIs
- Cystitis: PO 50-100mg qds x 5d
94
Nitrofurantoin
| • Patient counseling points
Take with food (incr absorption, reduce GI upset). Nausea, headache, dark coloured urine.
95
Nitrofurantoin
| • Contraindication/Precaution/pregnancy/ADR
Not for pyelonephritis
Avoid in renal impaired Crcl < 30ml/min, pregnancy at term (38-42 weeks), G6PD def
ADR: GI, Pulmonary fibrosis (unexplained malaise, cough, SOB). Tingling extremities (neuropathy) with dose-accumulation
96
Augmentin
| • Normal dose, frequency and duration for different classification of UTIs
Cystitis: PO 625mg bd x 3-7d
Pyelonephritis: PO 625mg bd/tds x 10-14d
97
Augmentin
| • Patient counseling points
Take with/ without food.
| Nausea, vomiting, diarrhoea
98
Augmentin
| • Contraindication/Precaution/pregnancy/ADR
Avoid in penicillin allergy, history of hepatic impairment with Augmentin/penicillin. Generally safe in pregnancy
ADR: cholestatic jaundice, GI esp diarrhea, vaginal mycosis
99
Fosfomycin
| • Normal dose, frequency and duration for different classification of UTIs
Cystitis: PO 3g single dose
| Complicated cystitis, CA-UTI: PO 3g EOD x 3 doses
100
Fosfomycin
| • Patient counseling points
Take with/ without food.
| Headache, diarrhoea
101
Fosfomycin
| • Contraindication/Precaution/pregnancy/ADR
Not for pyelonephritis, not for CrCl<30ml/min
ADR: headache, diarrhoea, vaginitis
102
What are the adjunctive therapy available for UTI?
* Pain and fever – paracetamol or NSAIDs
* Vomiting – rehydration
Urinary symptoms
- Phenazopyridine (Urogesic®) or Urine alkalization (relief in mild UTI, unproven benefit)
103
Phenazopyridine (Urogesic®) Dose and duration?
• Dose: 100-200mg tds
| treatment should be limited for the duration of symptoms
104
Phenazopyridine (Urogesic®) Precautions/ADR?
* Do not use in G6PD deficiency
| * ADR: nausea, vomiting, orange-red discolouration of urine and stool
105
Non-antimicrobial options for UTI prevention?
Cranberry juice
Intravaginal estrogen cream
Lactobacillus Probiotics
*May require more evidence but no harm trying
106
What is the goal of UTI tx?
1) Resolution of signs & symptoms
2) Bacteriological clearance
3) Absence of adverse drug reactions and allergies
107
By when can we expect Resolution of signs and symptoms in UTI if effective abx was given?
- Improvement or resolution by 24 to 72 hrs after initiation of effective antibiotics
108
What should be done if patient does not respond clinically within 2-3 days or has persistent positive urine/blood cultures?
Further investigation is needed to exclude bacterial resistance, possible obstruction, renal abscess, or some other disease process
109
What should we note for Bacteriological clearance in UTI?
- Repeat culture is not required for patients who responded
| - Culture to document clearance of infection for Pregnant women
