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Renal and Urology > Urinary Tract Infections > Flashcards

Urinary Tract Infections Flashcards

1
Q

What are important questions to ask in infection medicine?

A
  • What are risk factors for acquiring this infection?
  • What are the organisms responsible?
  • What is the pathogenesis?
  • Where is the infection – local vs systemic?
  • What is source and is there a seed (started in one place and gone to another?)?
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2
Q

Describe urinary tract anatomy

A

-Upper urinary tract (kidney, ureter)- pyelonephritis
-Lower urinary tract (sphincter, urethra, bladder)- cystitis
=Is it complicated?

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3
Q

Who gets uncomplicated UTIs?

A
  • Normal urinary tract

- Normal immune system

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4
Q

What are the risk factors for uncomplicated UTIs?

A

-Females
-Those with previous UTI
-Sexual activity
-Vaginal infection
-Diabetes
-Obesity
-Genetic susceptibility
-Older age
=Oestrogen deficiency (atrophic vaginitis, depletes vaginal mucosa which host protective organism lactobacilli)
=Cognitive impairment
*Broadly similar risk factors between cystitis and pyelonephritis

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5
Q

Who gets complicated UTIs?

A

Patients how have factors that compromise urinary tract system or immune system

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6
Q

What are the risk factors for complicated UTIs?

A

-Urinary obstruction, e.g. prolapse, prostatic enlargement
-Urinary retention caused by neurological disease
-Immunosuppression
-Renal failure
-Renal transplantation
-Pregnancy
-Presence of foreign bodies
eg indwelling catheters (CAUTI*) or other drainage devices
*CAUTI are MOST common cause of secondary bloodstream infections

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7
Q

What organisms cause UTIs (uncomplicated/complicated)?

A
  • E Coli= 75%/ 65%
  • Klebsiella pneumoniae (gram negative and resistant)= 6%/8%
  • S. saprophyticus= young sexually active women= 6%/2%
  • Enterococci= 5%/11%
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8
Q

Why does UTIs occur?

A
  • Contamination of urethra
  • Colonisation, swim upstream into bladder
  • Invade bladder wall (bacteria have pili and adhesions)
  • Inflammatory response/ fibrinogen accumulation in catheter
  • Neutrophil infiltration
  • Immune system subversion, bacterial multiplication
  • Biofilm formation
  • Epithelial damage by toxins and proteases
  • Ascend to kidneys
  • Colonisation, host tissue damage= bacteraemia
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9
Q

How does the bacteria invade the bladder wall?

A

-Type 1 pili
-Multiplication to form intracellular bacterial communities (IBC)
=exfoliate OR form quiescent bacteria reservoirs (QIR)
*To cause pyelonephritis bacteria must express pyelonephritis associated (P) pili

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10
Q

What are the bacterial virulence factors?

A 
-Adherence
=Pili
=Adhesins
-Toxin production
=eg haemolysins 
-Immune evasion
=eg capsule	
-Iron acquisition (nutrient)
-Other
=Flagella (swim upstream)
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11
Q

What are the host’s antibacterial defences?

A

-Urine:
=Extremes of osmolality, low pH and high urea concentration inhibit bacterial growth
-Urine flow and micturition
-Urinary tract mucosa (bactericidal activity, cytokines)
-Urinary inhibitors of bacterial adherence:
=Tamm-Horsfall protein
-Inflammatory response

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12
Q

Where can the infection be in a male patient?

A
  • Urethritis
  • Prostatitis
  • Epididymo-orchitis
  • Cystitis (bladder)
  • Pyelonephritis
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13
Q

Where is the source of infections?

A
  • Uropathogen from gut
  • Intracellular bacterial communities/quiescent intracellular reservoirs (recurrent UTIs)
  • Haematogenous – rare
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14
Q

What are the seeds of infection?

A
  • Bacteraemia common in pyelonephritis
  • Perinephric abscesses
  • Can rarely lead to remote deep seated infection
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15
Q

What is the clinical presentation of Pyelonephritis?

A
  • Loin pain/flank tenderness
  • Fever/rigors
  • Sepsis
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16
Q

What is the clinical presentation of Cystitis?

A

-Dysuria, frequency, urgency, suprapubic tenderness

17
Q

How does clinical presentation vary with age?

A
  • In infants (<2yrs) – vomiting/fever

- In elderly - less localised symptoms – confusion/falls

18
Q

What other questions may be asked on clinical presentation?

A 
-Where is dysuria?
=Throughout- urethritis
=End- issue in external vaginal area
=Dermatological- lichen planus, Bechet syndrome
=Foreign body= stent or stone
-Menstrual history
-Sexual history
19
Q

How do you diagnose UTIs?

A
  • Dipstick
  • Urine culture
  • Urinary biomarker
20
Q

Describe dipsticks

A

-ONLY TO BE USED IN PATIENTS <65
=asymptomatic bacteria
=Bacteria harmlessly live there, reside and colonise so positive test
-Useful ONLY in presence of clinical UTI symptoms – presence of nitrites (metabolite of bacteria) indicate a UTI is a possible. As low as 75% sensitivity.
=25% may have UTI and have nitrates negative of dipstick

21
Q

Describe urine culture

A

-Types of sample
=Mid stream urine (prevent peri-urethral contamination)
=Clean catch urine
=Catheter sample urine CSU – from port not bag (urine sits in bag)
=Other- urostomy/cystoscopy/pad
-Most laboratories will only detect ≥104 – 105 CFU/mL
-Generally significant if >105 CFU/mL

22
Q

Bacteriuria

A

Bacteria in urine

23
Q

Significant bacteriuria

A

Indicates that the number of bacteria in the voided urine exceeds the number expected from contamination from the anterior urethra

24
Q

Asymptomatic bacteriuria

A

Significant bacteriuria in a patient without symptoms

only ever treated in pregnant women

25
Q

Symptomatic bacteriuria

A

UTI

Culture results SUPPORT clinical diagnosis only

26
Q

What technologies have been developed for rapid detection?

A

-Flexicult – for primary care – culture at the bedside in 24 h
-Rapid detection using molecular markers
=Presence of bacteria
=Presence of inflammation (active in urinary tract?= biomarkers like IL6)
=Presence of antimicrobial resistance genes
-Challenge of phenotypic vs genotypic resistance
*all antimicrobial Rx to be prescribed with diagnostic

27
Q

What antibiotics are used for lower UTIs/ cystitis?

A
  • Trimethoprim (200mg every 12 hours)

- Nitrofurantoin (100mg every 12 hours) if risk factors for trimethoprim resistance and eGFR>30

28
Q

How are antibiotics used for cystitis?

A

Antibiotics are for amelioration and shortening of symptom duration in cystitis (self-limiting infection)
-RCT – trim decreased symptom duration by 4 days.
-What subgroup of patients could be managed without Antibiotics?
=Ibuprofen trial adverse events.
=25% culture negative
==Same symptom burden as culture positive
==Ibuprofen more effective as a treatment in culture negative group

29
Q

What are the problems with antimicrobial use?

A
  • Increases risk of recurrent UTI

- Increases antimicrobial resistance

30
Q

How do we choose antibiotics?

A

-Do they need antibiotics?
-Dependent on clinical syndrome (where?)
=Nitrofurantoin for cystitis ONLY
-What is resistance risk?
=E.coli
==60-70% amox resistance
==30% trim resistance
-Oral vs intravenous
=are there signs of SIRS (systemic inflammatory response) or sepsis?
=some MDR organisms only have IV choices available

31
Q

How are upper UTIs managed?

A

-Blood cultures
-Urine culture
-Gentamycin (bactericidal)
=Add amoxicillin (enterococcus)
=Add vancomycin
Review in 48 hrs

32
Q

How are catheter associated UTIs managed?

A

-Do not use dipstick
-Blood culture and urine culture, change catheter
-Temp above 38, no evidence of focal infection elsewhere, rigor, suprapubic or flank pain, haematuria, delirium
=Gentamycin

33
Q

How are UTIs managed in men?

A

-Is prostate involved (where?)

=Requires longer treatment and specific Abx to penetrate prostate

34
Q

How are UTIs managed in pregnant women?

A

-Avoid contra-indicated antibiotics
-Treatment of asymptomatic bacteriuria
=Historically thought to decrease risk of development of pyelonephritis which can lead to pre-term labour

35
Q

How are UTIs managed in children?

A

All children with confirmed UTI need investigation and consideration of vesico-ureteric reflux (causes renal scarring so transplants)

36
Q

What is the advice for recurrent UTI?

A
  • Fluid intake 2-2.5L per day (osmolarity)
  • Encourage water, diluting juice, decaf drinks, avoid fizzy drinks
  • Reduce alcohol – diuretic effect may cause dehydration
  • Intercourse advice - lubrication, pre and post coital voiding, personal hygiene, positioning to reduce friction
  • STI screening
  • Hygiene – wipe front to back
  • Avoid perfumed products and soap for intimate hygiene
  • Treat constipation (obstruct flow of urine)
  • Consider weight reduction
  • Smoking cessation
37
Q

Why do people get recurrent UTIs?

A
  • High grade vesico-ureteric reflux
  • Voiding dysfunction
  • Periureteral E Coli colonisation
  • E coli adhesions, bacterial reservoirs
  • Frequent sexual intercourse, spermicides
  • Familial tendency, uroepithelial cell susceptibility (secretor status), vaginal mucus properties
  • Candidate genes
38
Q

What drug helps prevent UTIs?

A

Methenamine= makes urine very hostile to bacteria

  • High dose vitamin C for acidity
  • Post-coital antibiotics
  • Oestrogen replacement (topical vaginal)

Renal and Urology (43 decks)

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