UTIs Flashcards
What are the types of UTI?
Cystitis (infection of bladder [lower UTI])
Pyelonephritis (infection of parenchyma and collecting system of kidneys (upper UTI)
Asymptomatic bacteriuria
What is pyelonephirtis?
Infection of parenchyma and collecting system of kidneys
Can cystitis and pyelonephritis coexist?
Yes, they often arise from the bottom upwards
What is asymptomatic bacteriuria?
Significant Bacteriuria without signs or symptoms. (must be seen in 2 consecutive samples)
Where is asymptomatic bacteriuria typically seen?
In children, pregnant women, and elderly
What is asymptomatic bacteriuria associated with?
Childbearing
What are uncomplicated UTIs?
Infection of bladder or kidney occurring in normal host without structural or functional abnormality in urinary tract
What are complicated UTIs associated with?
Factors that increase colonization and decrease efficacy of therapy.
Anatomical or functional abnormality
Immunocompromised host
Multi-drug resistant bacteria
Why are compicated UTIs problematic?
They are often more severe, difficult to treat, and recurrent
What kind of organisms cause haematogenous seeding?
S. aureus [bacteremia] or candida (rare with gram -ve bacteria)
Where do UTI causing bacteria typically originate from?
The bowel, they then colonise the lower vagina and periurethral mucosa
What are risk factors of UTIs?
Age-related
Gender related
Pregnancy
Sexual intercourse
Menopause
Congenital abnormalities
Renal calculi
Ureteral occlusion
Vesico-ureteral reflux
Residual urine in bladder (neurogenic bladder, urethral stricture, prostatic hypertrophy)
Instrumentation of urinart tract (especially urinary catheters)
What age groups cause spikes in incidence of UTIs?
Infancy
Preschool
Adult years (honeymoon cystitis in females)
pregnancy
Prostatism (males)
What serotypes of E.coli cause UTIs?
uropathogenic clones that have virulence factors with adhesion and invasion abilities.
What causes UTIs in a clinical setting?
E. coli (more antibiotic resistant than community acquired)
Proteus, Enterobacter, Serratia, Morganella
Pseudomonas aeruginosa
Enterococcus faecalis and faecium
Stenotrophomonas maltophilia
Corynebacterium urealyticum
Staph epidermidis
Candida albicans
What causes UTIs in a community setting?
E. coli
Staph saprophyticus
The other species studied in 2001 are way more rare in community setting
How are UTIs acquired in hospitals?
Rapid colonisation takes place by resident microflora.
Patients are often debilitated
UTI instrumentation typically colonised by bacteria
What are the clinical features of cystitis?
Dysuria (painful, burning urination)
Frequency (frequent passage of small amounts of urine)
Urgency (need to pass urine despite empty bladder)
Suprapubic heaviness or tenderness
Urine is turbid and may be bleedy and bad smelling
Fever usually absent
What are the symptoms of acute pyelonephritis?
Flank or back pain
Fever, chills
Rigors suggest bacteraemia
Headache, nausea, vomiting, prostration
Often with dysuria, frequency, urgency
What bacteria causes stones?
Corynebacterium urealyticum
When can UTIs have atypical clinical presentations?
Infants and children: fever, nausea, vomiting, and abdominal pain may predominate
Elderly: bacteraemia and shock
Subclinical pyelonephritis: seen in some women; dysuria, bacteriuria, with minimal or no symptoms of pyelonephritis
What are the types of urine specimens used to diagnose UTIs?
MSU (mid stream urine)
Suprapubic aspirate
CSU (cather)
Bag urine
Why is MSU taken?
To wash out colonizing bacterial
When is a suprapubic aspirate commonly used?
In babies or people powerless to control urine outflow
When is a catheter commonly used?
Whenever a patient has an obstruction or is unable to pass urine for whatever reason
What is the risk of leaving an indwelling catheter in for too long?
Increased risk of UTI
Where is bag urine used?
In babies but are readily contaminated with perinial bacteria
What kind of bacteria are often found contaminating specimens? How is this minimised?
Commensals are almost identical to UTIs. Using good collection techniques is essential.
What is used for lab examination of urine specimen for UTI diagnosis?
urine microscopy (white, red, and squamous epithelial cells are looked at under microscope)
Urine culture (quantitative culture where specimen is processed in a way to extrapolate size and growth rate)
What parameters are explored in urine microscopy?
White cell count
Red cell count (normal <6 x 10^6)
Squamous cells
What is the normal white cell count in urine?
<10 x 10^6/L (UTI will produce more than 1000 x 10^6)
What happens to leucocytes if urine is left standing?
It will break down
What does elevated WCC in urine look like and what is it called?
Cloudy and it is called pyuria
What are red cells in urine indicative of?
Sources of bleeding in urinary tract (calculi, tumors, inflammation, infection) or from extrusion through damaged glomeruli (glomerulonephritis)
What does morphology of red cells indicate?
abnormal red cells caused by extrusion through glomerulus. (called glomerular red cells)
What can contaminate urine red cells?
Menstrual blood
Where do squamous cells in urine come from?
Originate outside urinary tract. (they are caused by contamination of sample)
How are squamous cells expressed?
quantitatively or with ++++
What other things are reported by microscopy of urine?
Crystals
Casts - protein, cellular
Bacteria, eg. GNR +++
Yeasts; usually indicate contamination from vagina although candida UTI is possible but unlikely
What is the kass criterion?
<10^5/ml (10^8/L) concentration of a bacterium = contaminant
What did EH Kass determine?
Significant bacteriuria was defined by presence of a single species of bacterium in urine at a concentration of >10^5/ml (10^8/L). Bacteria at lower concentrations were likely to represent contaminants
What cutoff values for bacteriuria are currently accepted?
10^5/L or 10^2/ml (females)
10^6/L or 10^3/ml (males)
What factors should be considered while evaluating a UTI?
Patient’s age and sex
Symptoms
Recent or current antibiotic use
Method of collection
Number of leukocytes
Number of squamous epithelial cells
Number of bacterial species grown
Concentration of cultivated bacteria in the urine
What are UTIs in children associated with?
Urinary tract abnormalities:
Vesico-ureteric reflux
Ureteral duplication
Trabeculated bladder
Hydroureter
Uretopelvic junction obstruction
What causes vesicoureteric reflux?
Developmental defect causing UTIs at a young age
What happens when bladder contracts under normal circumstances?
The contraction of bladder closes the input of ureters preventing reflux
What percentage of children with UTIs go on to have Vesico-Ureteric Reflux?
20 - 30%
What is the problem with VesicoUreteric Reflux?
It causes renal scarring and in turn severe hypertension and renal failure. (UTI alone causes renal scarring too)
