22-02-23 – Urinary Tract Infections Flashcards
Learning outcomes
- Identify which pathogens commonly cause UTIs
- Recognise main presenting symptoms of a patient with UTI
- Outline the clinical and laboratory diagnosis of UTIs
- Explain the complications that may arise if a UTI is left untreated
- Recognise the assoociation between different bacterial species and certain at-risk patients who develop UTIs
- Understand how the host is protected against UTIs
- Recognise the role of various bacterial virulence factors in the causation of UTIs
- Identify the most appropriate choice of treatment(s) to successfully treat UTIs
Definitions
* Micturition
* Dysuria
* Bacteriuria
* Haematuria
* Pyelonephritis
* Cystitis
* Urethritis
* Prostatitis
- Definitions
- Micturition - urination
- Dysuria - pain on urination
- Bacteriuria - presence of bacteria in the urine
- Haematuria - presence of blood in urine
- Pyelonephritis - kidney infection
- Cystitis - infection confined to the bladder
- Urethritis - inflammation of the urethra
- Prostatitis - prostate infection
How common are UTIs?
What is their incidence?
What % of antimicrobial prescriptions in primary care do they make up?
Which sex are they most common in? How common are they in women?
What age do UTIs primarily occur in in men?
- UTIs are one of the commonest infections.
- UTI incidence is 50,000 per million persons per year
- They account for 15% of all antimicrobial prescriptions in primary care.
- They are more common in women than men
- 50% of adult women have ≥1 UTI in lifetime, particularly common in postmenopause.
- Occur inn men primarily >50 years of age
What % of UTIs are single are isolated attacks?
What % of UTIs are recurrent attacks?
- 90% of UTIs are single or isolated attacks
- 10% of UTIs are recurrent attacks:
1) 20% of these recurrent attacks are relapsed, meaning infection occurs from a different microorganism from the one before
2) 80% of recurrent attacks are reinfections, meaning they are caused by the same microorganism as the infection before
What are 6 signs and symptoms of Lower UTIs?
What are 3 signs and symptoms of Infections of pelvis and kidney (acute pyelonephritis)?
- 6 signs and symptoms of Lower UTIs:
1) Frequency of micturition
2) Urgency to urinate
3) Dysuria
4) Suprapubic pain & tenderness
5) Haematuria
6) Smelly / cloudy urine - 3 signs and symptoms of Infections of pelvis and kidney (acute pyelonephritis)?
1) Loin pain & tenderness
2) High fever
3) Systemically unwell
What are 11 predisposing factors for UTIs?
- 11 predisposing factors for UTIs:
1) Obstruction: calculi, tumors, benign prostate hyperplasia
2) Vesicoureteral reflux (VUR) – urine going back up the ureter
3) Incomplete bladder emptying (neurogenic, voluntary)
4) Diabetes
5) Sickle cell
6) Immune compromise
7) Bladder instrumentation / foreign bodies
8) Congenital structural abnormalities
9) Sexual activity
10) Pregnancy
11) Catheterisation
* Incremental risk of CAUTI associated with each additional day of catheterisation.
What are 8 factors in the urinary tract host defenses?
- 8 factors in the urinary tract host defenses:
1) Urine - osmolality, pH
2) Sloughing of epithelial cells
3) Urine flow and micturition
4) Mucosal inhibitors of bacterial adherence
5) Complement activation
6) Inflammatory response
7) Immune responses
8) Commensals
What is the most common cause of community and hospital acquired UTIs?
What are 5 gram-negative bacteria that cause UTIs?
- The most common cause of community and hospital acquired UTIs is E.coli
- 5 gram-negative bacteria that cause UTIs:
1) Escherichia coli (E. coli)
2) Klebsiella sp.
3) Proteus mirabilis
4) Enterobacter sp.
5) Serratia sp
What are 2 different serotpyes of Uropathogenic E. coli (UPEC)?
What are 3 virulence factors of Uropathogenic E. coli (UPEC)?
- 2 different serotpyes of Uropathogenic E. coli (UPEC):
1) O (somatic)
* Antigen based on bacterial cell wall
2) K (capsular)
* Antigen based on capsule
- 3 virulence factors of Uropathogenic E. coli (UPEC):
1) Fimbriae (adhesion)
2) K antigen
3) Haemolysin
How can E.coli adhere to uroepithelial cells?
What are the 2 different types of fimbriae (pili)?
- E.coli can adhere to uroepithelial cells through fimbriae (pili)
- 2 different types of fimbriae (pili):
1) Type 1 fimbriae
2) Type P fimbriae
What 4 events can occur when bacteria adhere to uroepithelial cells?
- 4 events that can occur when bacteria adhere to uroepithelial cells:
1) Iron acquisition machinery activated via siderophores
2) Stimulates growth and reproduction
3) Once a monolayer has formed a biofilm may develop
4) Bacteria with type 1 fimbriae may become internalised in phagocytes and epithelial cells
What are 2 pathogenic factors of E.coli?
What type of structure are they?
How do they contribute to the virulence of E.coli?
- 2 pathogenic factors of E.coli:
1) K Antigen
* Polysaccharide
* Forms a micro-capsule
* Confers resistance to phagocytosis
2) Haemolysin
* Cytolytic exo-protein
* Damages tissue membranes in vivo
* Causes kidney damag
What type of bacteria is Proteus mirabilis?
What are 3 virulence factors of Proteus mirabilis?
- Proteus mirabilis is a Gram-negative bacillus
- It is a facultative anaerobe - an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent
- 3 virulence factors of Proteus mirabilis:
1) Peritrichous flagellae
* If a bacterium has a peritrichous arrangement of flagella, counterclockwise rotation of the flagella causes them to form a single bundle that propels the bacterium in long, straight or curved runs without a change in direction
2) Produces urease
* Bacterial urease splits urea and promotes the formation of ammonia and carbon dioxide leading to urine alkalinization and formation of phosphate salts
3) Swarming ability
* Rapid and coordinated multicellular migration of bacteria across a moist surface
What are 5 gram-positive bacteria that cause UTIs?
- 5 gram-positive bacteria that cause UTIs:
1) Staphylococcus saprophyticus
2) Staphylococcus epidermidis
3) Enterococcus sp.
4) Corynebacteria
5) Lactobacillus
What type of bacteria is Staphylococcus saprophyticus.
Where can Staphylococcus saprophyticus be found in the body?
What is it a common risk of?
What can increase the risk of UTIs from Staphylococcus saprophyticus?
- Staphylococcus saprophyticus is a gram-positive bacterium
- Staphylococcus saprophyticus is a coagulase-negative staphylococci (CoNS), which are a type of staph bacteria that commonly live on a person’s skin
- Staphylococcus saprophyticus is part of the normal microbiota of female perineum & vagina
- Staphylococcus saprophyticus is a common cause of community acquired UTIs and can cause symptomatic cystitis
- Sexual activity increases risk of UTIs from Staphylococcus saprophyticus
What are 8 other microorganisms that can cause UTIs?
- 8 other microorganisms that can cause UTIs:
1) Candidia albicans
2) Trichomonas vaginalis
3) Schistosoma haematobium
4) Mycobacterium fortuitum
5) Histoplasma capsulatum
6) Polyomaviruses
7) CMV
8) Rubella
What kind of microorganism is Candida albicans?
What role does Candida albicans play in the body?
What condition can Candida albicans cause?
What groups is Candida albicans an opportunistic pathogen in?
What is it often associated with?
- Candida albicans is a Diploid fungus (yeast)
- Candida albicans is a commensal organism
- Candida albicans can cause Candidiasis (thrush)
- Candida albicans is an important opportunistic pathogen in immunocompromised individuals
- It is often associated with antibiotic use
What type of microorganism is Trichomonas vaginalis?
Is it commensal, symbiotic or pathogenic?
What pH does it prefer?
What condition does it cause? What sex is it more common in?
- Trichomonas vaginalis is a protozoan and a pear-shaped flagellate
- Trichomonas vaginalis is pathogenic, while other species are commensal
- It Prefers pH ~6.0
- Trichomonas vaginalis causes Trichomoniasis
- It is more common in females
What type of microorganism is Schistosoma haematobium?
What can it cause?
Where is Schistosoma haematobium found?
How does it gain access to the host?
Where does it mature?
Where can its eggs penetrate?
How is Schistosoma haematobium treated?
- Schistosoma haematobium is a Trematode worm
- It can cause Schistosomiasis (bilharzia)
- Schistosoma haematobium is found in contaminated water
- It gains access to host through skin
- It matures in liver and its eggs travel to and penetrate bladder
- Schistosoma haematobium is treated with praziquantel
What are 3 ways UTIs can be diagnosed?
- 3 ways UTIs can be diagnosed:
1) Clinical
2) Urine dipstick
3) Laboratory diagnosis
How are UTIs primarily diagnosed?
How common is bacteriuria women that present with symptoms of acute UTI?
What does the probability rise to when dysuria and frequency are both present?
What is indicated in this case?
- The diagnosis of UTI is primarily based on symptoms and signs
- The probability of bacteriuria in otherwise healthy women who present to their general practitioner (GP) with symptoms of acute UTI is estimated at between 50- 80%.
- If dysuria and frequency are both present, then the probability of UTI is increased to >90% and empirical treatment with antibiotic is indicated, with no need for further testing.
Why do we use urine dipstick when testing for UTIs?
What substances are we mainly looking for?
What other substances may be present?
- We use urine dipstick when testing for UTIs as it serves as an indirect marker of inflammatory response in the host
- The main thing we are looking for is nitrites
- We may also see blood or leukocytes and other inflammatory cells
In what 2 scenarios would we use urine dipstick to test for UTIs?
In what 3 scenarios would we not use urine dipstick to test for UTIs?
- 2 scenarios we would use urine dipstick to test for UTIs:
1) If the woman is under 65 years of age, and does not have risk factors for complicated UTI, urine dipstick can be used as an aid to diagnosis
2) Children 3 months – 16 years old, as they cant verbalise as well
- 3 scenarios would we not use urine dipstick to test for UTIs:
1) Do not use urine dipstick tests or microscopy to diagnose UTI in men — dipsticks are poor at ruling out infection
2) Dipstick becomes more unreliable in patients over 65 years old
3) Do not use dipstick test for diagnosing UTI in older people or people with indwelling catheters
Scottish Antimicrobial Prescribing Group (SAPG) Guidelines for diagnosing UTI in older people
