UTIs Flashcards
Do UTIs affect men or women more ?
• More common in women than men
20-30% women have ≥1 UTI in lifetime
Describe the time frame of UTIs.
Usually acute and short lived (90%)
In a minority of cases (10%), they are recurrent, in which case they may either be relapses (20%) or reinfections (80%)
What are the signs and symptoms of lower UTIs ?
– Frequency of micturition – Urgency to urinate – Dysuria – Suprapubic pain and tenderness – Haematuria – Smelly / cloudy urine
What are signs and symptoms of pelvis and kidney infection ? What is the name for such an infection ?
– Loin pain and tenderness
– High fever
– Systemic upset
Acute pyelonephritis
Identify possible complications of UTIs.
Stones
Obstruction
Polycystic kidney
Vesicoureteric reflux
Overall, risk of kidney damage and septiciemia
Identify possible diseases associated with complications from UTIs.
Diabetes Mellitus
Sickle Cell
Analgesic Abuse
Identify factors favoring UTIs.
Bacterial attributes:
- Urease
- Haemolysins
- Adhesion in uroepithelium (P. fimbriae in E. Coli)
- Capsular antigens
Host factors:
- Renal calculi
- Ureteric reflux
- Tumors in and adjacent to UT
- Pregnancy
- Bladder stones
- Catheterisation
- Short urethra in women
- Prostatic hypertrophy
- Neurologic problems (incomplete bladder emptying, large V of residual urine, loss of sphincter control)
Identify the main pathogens responsible for UTIs.
Community acquired:
- E-coli
- Coagulase negative staph
Hospital (nosocomially) acquired:
- E-coli
- Proteus Mirabilis
- Other gram negatives (Klebsiella Enterobacter, Pseudomonas Aeruginosa)
- Other gram positives (Staph epidermidis, Staph aureus)
Identify the main gram negative bacteria responsible for UTIs.
- Escherichia coli (both community acquired and nosocomial)
- Proteus mirabilis (esp. nosocomial infections)
- Klebsiella sp.
Which type of E. Coli causes UTIs ?
Uropathogenic E. coli (UPEC)
What are the main serotypes of E Coli ?
O (somatic) - O antigens are found in bacterial cell wall
K (capsular) - K antigens are in capsule
Identify the main virulence factors for E. Coli in UTIs.
– Fimbriae (adhesion)
– K antigen
– Haemolysin
Describe how and where E. coli adheres, in UTIs.
-Specific adhesion to uroepithelial cells
-Through fimbriae (pili), two types:
Type 1 fimbriae
Type 2 fimbriae
What are the bacterial responses of E. coli to adhesion ?
- Iron acquisition machinery activated via siderophores
- Stimulates growth and reproduction
- Once a monolayer has formed a biofilm may develop
- Bacteria with type 1 fimbriae may become internalised in phagocytes and epithelial cells
What kind of molecule is K antigen ? Describe the advantages conferred by the K antigen, to E. coli in UTIs.
- Polysaccharide
- Forms a microcapsule, so confers resistance to phagocytosis
What kind of molecule is haemolysin ? Describe the advantages conferred by Haemolysin, to E. coli in UTIs.
- Cytolytic exo-protein
* Damages tissue membranes in vivo, and causes kidney damage
State the main classifications of Proteus Mirabilis.
- Gram negative
- Facultative anaerobe
- Bacillus
Identify the main virulence factors of Proteus Mirabilis.
- Peritrichous flagellae
- Produces urease
- Swarming ability
Identify the main gram positive bacteria responsible for UTIs.
- Staphylococcus saprophyticus
- Staphylococcus epidermidis
- Enterococcus sp.
Are gram positive bacteria more responsible for community acquired or nosocomially acquired infections ?
More responsible for nosocomially acquired infections
State the main classifications of Staph. saprophyticus.
- Gram positive
- Coagulase negative
- Normal microbiota of female perineum and vagina
What UTI infection does Staph. saprophyticus usually cause ?
Symptomatic cystitis
What is a prediposing factor to UTI due to Staphylococcus saprophyticus ?
• Sexual activity increases risk of UTI due to Staphylococcus saprophyticus (commonly causes community acquired UTIs)
Identify other pathogens (other than bacteria) associated with UTIs.
- Candidia albicans
- Trichomonas vaginalis
- Schistosoma haematobium
What kind of pathogen is Candida Albicans ? What infections does it cause ?
- Diploid fungus (yeast)
- Commensal (so not pathogenic straight away)
Causes candidiasis (thrush). Especially in immunocompromised individuals (opportunistic pathogen), and often associated with antibiotic use.
What kind of pathogen is Trichomonas Vaginalis ? What infections does it cause ?
- Protozoan
- Pear-shaped flagellate
- Pathogenic (other species are commensal)
Causes trichomoniasis.
What pH does Trichomonas Vaginalis prefer ?
• Prefers pH ~6.0
Describe the epidemiology of Trichomonas vaginalis infections.
Less common in males
What kind of pathogen is Schistosoma haematobium ?What infection does it cause ,
• Trematode worm
Causes Schistosomiasis (bilharzia).
How is Schistosoma haematobium transmitted ? Briefly describe its life cycle.
- Found in contaminated water, and gains access to host through skin
- Matures in liver + eggs travel to and penetrate bladder
What is the treatment for Schistosoma haematobium infections ?
• Treatment with praziquantal
Identify the main entry points for bacteria in catheterisation.
- Urethral meatus and around catheter
- Connection to drainage bag and reflux from bag to tubing
Why is catheterisation associated with a higher risk of UTI ?
Because
1) Gives pathogens surface to form biofilm
2) Disrupts normal protective functions of urinary system (flushing etc.)
What kind of testing may be required in UTI ?
- Urine specimens for lab analysis
- Urine dipstick test
Identify the main urine specimens for lab analysis which may be required in UTIs, and identify the main feature of each.
1) MSU–mid-stream specimen of urine (significant bacteriuria, >10^5 per ml)
2) CSU – catheter specimen of urine (significant bacteriuria, lower number of micro-organisms than MSU)
3) Suprapubic aspiration of bladder urine (for Schistosoma haematobium and other rare occasions)
In a mid-stream specimen of urine, how many strains of pathogens should be found ?
If infection, only one.
If more than one, means it’s been contaminated.
What features of the urine dipstick test would point to a UTI ?
(Bright color and very foul smell in appearance)
- Nitrates reduced into nitrites (so increased nitrites)
- Increased leukocytes (also, leukocytes produced esterases, but that isn’t shown by test)
Identify the main host defenses of the urinary tract.
- Urine - osmolality, pH
- Sloughing of epithelial cells
- Urine flow and micturition
- Mucosal inhibitors of bacterial adherence
- Complement activation
- Inflammatory response
- Immune responses
- Commensals
Identify oral antibiotics used for UTIs.
- Co-trimoxazole (first line therapy, go-to drug)
- Nitrofurantoin (go-to drug for E. coli and staph)
- Nalidixic acid
- Co-amoxiclav
- Trimethoprim
- Ciprofloxacin
Also, drink plenty of water
