MB10 Urinary Tract Infections Flashcards Preview

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Flashcards in MB10 Urinary Tract Infections Deck (26):


  1. ​What are the difficulties?
  2. What is recurrent infection an indication of?
  3. What is the trend in 
    1. Males
    2. Females

  1. Common, Life threatening, Complicated
  2. radiological investigation especially in children

  3. Trend

    1. Men get more complicated UTIs later in life because of prostate disease

    2. Women have acute, easier-treated UTIs (more likely to have them younger)


What are the main modes of acquisition of a UTI?

(most common in bold)




What are the factors that predispose to UTI?

Bacterial Factors

  • Capsular Antigens
  • Hemolysins
  • Urease
  • Adhesion to uroepithelium (e.g fimbriae in E.Coli)
  • Introital colonisation 

Host Factors

  • Renal calculi
  • Ureteric reflux
  • Tumours in and adjacent to urinary tract
  • Pregnancy, bladder stones
  • Neurologic problems 
    • Incomplete bladder emptying
    • large volume of residual urine
    • Loss of sphincter control
  • Prostatic hypertrophy
  • Short urethra in women
  • Catheterization



  1. Uncomplicated UTI?
  2. Complicated UTI?

  1. UTI by a usual pathogen in a normal urinary tract in a person with normal renal function

  2. UTI where there is anatomical, functional, pharmacological factors predisposing to persistent infection 


What will predispose to a complicated UTI?

Anatomical: stones, vesicoureteric reflux, neurogenic bladder, catheter, urinary obstruction

Multi-drug resistant organism: carbapenemase producing enterobacteriaceae (CPE)

Impaired host defence: diabetes mellitus, immunosuppressed

Impaired renal function or post renal transplant 


What is the most common cause for urinary tract infections?



Organisms in community acquired are just as prominent in hospitalised, however there is a greater variety of UTI causing agents in the community.


  1. Which organisms live in the gut, can colonise the perineum and ascend up the urethra and colonise it?
  2. Which from the Non-Enterobacteriaceae is likely to cause UTIs?
  3. Which of the gram-positive cocci chains is likely to cause UTI?

  1. ENTEROBACTERIACEAE (gram negative rods) = Esherichia Coli, Klebsiella pneumoniae, Proteus mirabilis
  2. Pseudomonas aeruginosa

  3. Enterococcus faecalis


What are the clinical features of 

  1. Acute lower UTIs
  2. Upper UTIs

  1. Dysuria, urgency, frequency, nocturia, strangury (feel like you need to go), haematuria, suprapubic pain, smell
  2. Fever, nausea, malaise, loin pain, tenderness


  1. What is Asymptomatic Bacteriuria
  2. How is it picked up?
  3. Who is it particularly importnant to screen?

  1. —Significant numbers of bacteria in urine in absence of symptoms
  2. Screening 
  3.  Pregnant women, Young children, people undergoing instrumentation of the urinary tract (bacteremia), elderly and diabetics


How are UTIs normally diagnosed?

by symptoms

  • Dipstick
  • Culture and sensitivites 
  • Urine collection and lab analysis
  • Special collections



  1. What do they detect?
  2. What could the results indicate?


  1. Urinary nitrate (thought to be a metabolite produced by bacteria in the urine) and urinary leucocyte esterase (WBCs will be involved in an inflammatory response)
  2. +/+ =UTI very likely – treat empirically

    -/-  = UTI unlikely – no treatment unless…..

    -/+ = Possible UTI – consider culture…..


When should Culture and Sensitivities be conducted in UTI diagnosis?

  • —Pregnancy  - 1st antenatal visit or if symptoms
  • —Suspected pyelonephritis - (signs of upper UTI)
  • Suspected UTI in men
  • Recurrent UTI
  • Catheterised – only if evidence of systemic infection
  • Failed treatment or persistence
  • Abnormal Urinary Tract
  • Post Renal Transplant


UTI diagnosis - Urine Collection

  1. Normally, what state is the urine in the bladder?
  2. How should a sample be collected?
  3. When should it be cultured?
  4. What is the basis of the Mid-steam sample collection?
  5. How is it intially analysed?

  1. Sterile
  2. —Clean- MSU- before antibiotics, Collected into sterile container

  3. —Cultured within one hour or held at 4°C

  4. flushes away the transient colonisation of the perineurium. This next urine is actually the urine IN THE BLADDER

  5. Clear result in less than 24 hours = counting didn't reach the threshold (WBCs and bacteria counted). If positive - ID and sensitivies (antibiotic sensitivity testing) (48hours)


UTI Diagnosis

  1. What constitutes an 'infection'?
  2. What constitutes 'contamination'?

  1. Properly collected MSU contain >105 CFU/ml of single bacterial spp (bacteria per ml)

  2. <104 CFU/ml – more than one spp




What is the unit CFU?

colony-forming unit (CFU or cfu) is a measure of viable bacterial or fungal cells.CFU measures only viable cells. For convenience the results are given as CFU/mL (colony-forming unitsper milliliter) for liquids, and CFU/g (colony-forming units per gram) for solids.



When are special collections made in order to diagnose UTIs?

  • —Babies & children
    • Bag urine
    • Supra pubic aspiration
  • —Patients with catheters –collected from catheter using needle & syringe, not from bag (colonisation)
  • —Special urine samples to detect
    • M. tuberculosis
    • S. haematobium


How are UTIs treated?






In healthy non-pregnant women, how can liklihood of a UTI be considered?




Trimethoprim and nitrofurantoin

Treat empirically – 3 day course

Trimethoprim 200mg bd

Nitrofurantoin 50-100mg bd/qid


Dysuria/frequency in absence of vaginal symptoms = very likely UTI >95%

—Dysuria/frequency in presence of vaginal symptoms = less likely UTI ~20%


What are the special UTI cases that need to be considered?

Ascending, recurrent, young, pregnant, catheters, male


Acute Pyelonephritis 

  1. What would the uncomplicated form involve?
  2. What would the complicated form involve?
  3. What are the symptoms?
  4. What does the treatment involve?

  1. —Usual pathogen in normal renal anatomy and function
  2. —Abnormal anatomy, stones, catheter, immunocompromised, instrumentation, obstruction, pregnancy, persistent lower uti

  3. —High fever, rigors, loin pain, nausea, vomiting ± lower UTI symptoms

  4. Broad spectrum, usually IV initially

    1. Co-amoxiclav

    2. Piperacillin-tazobactam

    3. Ciprofloxacin?


Explaining reccurence in women

  1. Premenopausal 
  2. Postmenopausal
  3. What would be the steps in the mangagement of this recurrence?

  1. —Sexual intercourse

    —Contraceptives- affect hormones, alters vaginal flora. 

    —Antibiotic usage

  2. —Oestrogen deficiency

    —Urogenital surgery


  3. Investigations of uro-genital tract

    Patient / Professional initiated antimicrobial therapy for new episodes

    Antimicrobial prophylaxis – eg Trimethoprim 50mg at night – 6-12 months

    Cranberry products (prophylaxis, not treatment)


Paediatric UTI

  1. Why should you have a high index of suspicion?
  2. What is common in children with anatomic abnormalities?
  3. In what age group is the risk of renal scares most significant?
  4. What is recommended in every febrile infant or young child following the first UTI?
  5. What should the treatment be?

  1. Infants may present with non-specific signs and symptoms 
  2. Vesicoureteral reflux

  3. Younger children

  4. Imagining of the urinary tract

  5. —Prompt antibacterial to minimise renal scarring

    —If further investigations are considered necessary→ antibacterial prophylaxis (low dose, specialist treatment)

    —Long term low dose therapy in case of vesicoureteric reflux & renal scarring 


What happens in the bladder when reflux occurs?

In reflux, the valves don't close, and urine is forced back towards the kidney 


UTI in Pregnancy

  1. How can this be diagnosed?
  2. What is the treatment?
  3. What drugs should be used?
  4. Why is it so important to treat?

  1. Asymptomatic bacteriuria on screening – repeat culture to confirm

  2. treat empirically, then using sensitivity data (Repeat culture 7 days post treatment and 4 weekly thereafter until end of pregnancy)

  3. Nitrofurantoin 50-100mg bd/qid  Caution: end of pregnancy

    1. Cefalexin 500mg bd (B lactam antibiotic)

    2. Trimethoprim 200mg bd  Caution: folate antagonism: start of pregnancy

    3. Amoxicillin 250mg tid

  4. If you allow bacteria to colonise the bladder. Because of the obstruction, upper UTI risk is VERY HIGH- ANY bacteria in the urine of a pregnant woman is treated


Catheter Associated UTI

  1. What are the symptoms?
  2. How is it diagnosed?
  3. How is it treated?

  1. Fever, flank pain, suprapubic discomfort, nausea, confusion

  2. C&S (Culture ONLY if symptomatic)

  3. Prophylaxis unlikely to be helpful

    Management of Symptomatic UTI – Review catheter care/function. take urine for C&S before removal, change catheter

    Treat - Empirically with trimethoprim or nitrofurantoin 7- 14 day course. As Upper UTI if flank pain. 


UTI in Men

  1. Give examples of these?
  2. What are some predisposing factors?
  3. What test needs to be carried out?
  4. How is it treated?

  1. Prostatitis, epididymitis, orchitis
  2. Incomplete bladder emptying, abnormal function or structure, previous surgery, immunocompromised

  3. Culture and Sensitivity  (essential)

  4. Treat empirically – 7- 14 day course




Generally, what drugs are used in UTI treatment?

—Trimethoprim/ Nitrofurantoin

—Co-amoxiclav/ Piperacillin-tazobactam/ Ciprofloxacin