48 Urinary tract infections Flashcards
What is micturition?
Urination
What is dysuria?
Pain on urination
What is bacteriuria?
Presence of bacteria in urine
What is haematuria?
Presence of blood in urine
What is pyelonephritis?
Kidney infection
What is cystitis?
Infection confined to bladder
What is urethritis?
Inflammation of urethra
What is prostatitis?
Prostate infection
What is the aetiology of UTIs?
- Women > men
- 20-30% women have ≥ 1 UTI in lifetime
- In men primarily >50 years of age
- Occurs in normal urinary tract
- Incidence 50, 000 per million persons per year
What type of attacks are UTIs?
- Single or isolated attack (90%)
- Recurrent attacks (10%)
- relapse (20%)
- reinfection (80%)
Outline the signs and symptoms of UTIs:
Lower?
Infection of pelvis and kidney (acute pyelonephritis)?
• Lower UTIs: – Frequency of micturition – Urgency to urinate – Dysuria – Suprapubic pain & tenderness – Haematuria – Smelly / cloudy urine
• Infection of pelvis and kidney (acute pyelonephritis):
– Loin pain & tenderness
– High fever
– Systemic upset
What are the factors favouring UTIs:
Bacterial attributes?
- capsular antigens
- hemolysins
- urease
- adhesion to uroepithelium (e.g.P. fimbriae in E.coli)
- introital colonisation
What are the factors favouring UTIs:
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
- catherisation
What are the common causes of UTIs:
Common acquired?
- E.coli
- coagulase-negative staphylococci
- other gram-positives e.g. Staphylococcus epidermis, Staphylococcus aureus, Enterococcus faecalis
What are the common causes of UTIs:
Hospital (nosocomially) acquired?
- candida
- proteus mirabilis
- other gram-negatives e.g. Klebsiella, Enterobacter, Serratia, Pseudomonas aeruginosa
What are the gram negative bacteria UTIs?
- Escherichia coli
- Proteus mirabilis
- Klebsiella sp.
- Enterobacter sp.
- Serratia sp.
Which virulence factors are expressed by uropathogenic E.coli (UPEC)?
- Fimbriae (For adhesion, Type 1 and Type P)
- K antigen
- Polysaccharide
- Forms a micro-capsule
- Confers resistance to phagocytosis - Haemolysin
- Cytolytic exo-protein
- Damages tissues membranes in vivo
- Causes kidney damage
What serogroups are in uropathogenic E.coli (UPEC)?
Certain serogroups of O and K serotypes
• O (somatic) - O1, O2, O4, O6, O7, O75
• K (capsular) K1, K2, K3, K5, K12, K13
What does E.coli adhere to and what are the 2 types of fimbriae (pili)?
- Specific adhesion to uroepithelial cells
- Fimbriae types:
- Type 1 fimbriae
- Type P fimbriae
What is the bacterial response 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
Features of proteus mirabilis as a causative agent of UTIs?
- Gram negative
- Facultative anaerobe
- Bacillus
- Peritrichous flagellae
- Produces urease
- Swarming ability
What are the gram positive bacteria in UTIs?
- Staphylococcus saprophyticus
- Staphylococcus epidermis
- Enterococcus sp.
- Corynebacteria
- Lactobacillus
Features of Staphylococcus saprophyticus as a causative agent for UTIs?
- Gram positive
- Coagulase negative
- Normal microbiota of female perineum & vagina
- Sexual activity increases risk of UTI
- Commonly causes community acquired UTIs
- Symptomatic cystitis
What other organisms (fungi/yeast/protozoal) involved in UTIs?
- Candida albicans
- Trichomonas vaginalis
- Schistosoma heamatobium
- Myobacterium fortuitum
- Histoplasma capsulatum
- Polyomaviruses
- CMV
- Rubella
Features of Trichomonas vaginalis as a causative agent for UTIs?
- Protozoan: Most common protozoal cause of UTIs
- Pear-shaped flagellate
- T. vaginalis is pathogenic
- Other species are commensal
- Prefers pH ~6.0
- Trichomoniasis
- Less common in males
Features of Trichomonas vaginalis as a causative agent for UTIs?
- Protozoan: Most common protozoal cause of UTIs
- Pear-shaped flagellate
- T. vaginalis is pathogenic
- Other species are commensal
- Prefers pH ~6.0
- Trichomoniasis
- Less common in males
What are the 3 different types of urine specimens for lab analysis?
- MSU (Mid-stream Specimen of Urine)
- Significant bacteriuria
- >10^5 per ml - CSU (Catheter Specimen of Urine)
- Significant bacteriuria
- Loer number of micro-organisms than MSU - Suprapubic aspiration of bladder urine
- For schistosome haematobium and other rare occasions
Specimens used to perform urine dipstick test. (Nitrites present = infection)
What are the 3 different types of urine specimens for lab analysis?
- MSU (Mid-stream Specimen of Urine)
- Significant bacteriuria
- >10^5 per ml - CSU (Catheter Specimen of Urine)
- Significant bacteriuria
- Loer number of micro-organisms than MSU - Suprapubic aspiration of bladder urine
- For schistosome haematobium and other rare occasions
What shows there’s infection in urine dipstick test?
Nitrites present
Increased leukocyte esterase
Urinary tract host defences?
- Urine - osmolality, pH
- Sloughing of epithelial cells
- Urine flow and micturition
- Mucosal inhibitors of bacterial adherence
- Complement activation
- Inflammatory response
- Immune responses
- Commensals
What chemical is found in cranberry juice that helps to prevent E.coli adherence that leads to UTIs?
Proanthrocyanidins
Oral Antibiotics for UTIs?
- Co-trimoxazole
- Nitrofurantoin
- Nalidixic acid
- Co-amoxiclav
- Trimethoprim
- Ciprofloxacin
Identify which pathogens commonly cause UTIs
*E.coli (gram neg)
*Proteus mirabilis (gram neg)
*S. saprophyticus (gram pos)
Candida albicans
Schistosoma haematobium
T. vaginalis
