Urinary tract
infections
By Dr. Haitham Nabeel
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UTI in adults
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Introduction
• Urinary tract infection (UTI) is the term used to describe
acute urethritis and cystitis caused by a microorganism.
• It is a common disorder, accounting for 1–3% of
consultations in general medical practice.
• The prevalence of UTI in women is about 3% at the age of
20, increasing by about 1% in each subsequent decade.
• In males, UTI is uncommon, except in the first year of life
and in men over 60, when it may complicate bladder
outflow obstruction.
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Etiology
• Bacteria
• Infection ascends from the urethra to the bladder.
• Can ascend further to the ureters and the renal pelvises
• Causative organisms
• Escherichia coli: leading cause of UTI (approx. 80%)
• Staphylococcus saprophyticus: 2nd leading cause of UTI in sexually
active women
• Klebsiella pneumoniae: 3rd leading cause of UTI
• Proteus mirabilis
• Produces ammonia, giving the urine a pungent or irritating smell
• Associated with struvite stone formation
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Risk factors
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Why UTI are more common in women?
• Several factors account for this including:
• The urethra is shorter,
• Absence of bactericidal prostatic secretions,
• The anal and genital regions are in close proximity,
• Sexual intercourse may cause minor urethral trauma and
transfer bacteria from the perineum into the bladder.
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Classification
• Urinary tract infections are classified and treated
based on location, severity, source of infection, and
frequency.
Classification method Types
By clinical presentation Asymptomatic bacteriuria Vs. Urinary tract infection (UTI)
By location Lower UTI Vs. upper UTI
By severity Uncomplicated UTI Vs. complicated UTI
By source of infection Community-acquired UTI Vs. Healthcare-associated UTI
By frequency Recurrent UTI
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Classification
Asymptomatic bacteriuria Urinary tract infection (UTI)
• Significant • Bacteriuria and clinical
bacteriuria without features of UTI
clinical features of UTI
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Classification
Lower UTI Upper UTI
• Infection of • Infection of
the bladder (cystitis), the
most common location of the kidneys and ureter
UTIs, and/or (pyelonephritis)
urethra (urethritis)
• Commonly associated with
infection of
the prostate (prostatitis) in
men
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Classification
Uncomplicated UTI Complicated UTI
• Infection in nonpregnant, premenopausal women • Infection in patients with risk factors for infection, treatment
failure, or serious outcomes, including:
without further risk factors for infection, treatment • Male sex
failure, or serious outcomes • Pregnancy
• Postmenopause
• Significant anatomical or functional abnormalities
• Immunosuppression
• Renal failure
• Metabolic disorders (e.g., diabetes)
• History of UTIs in childhood
• Infection associated with recent instrumentation or medical
devices, e.g.:
• Cystoscopy
• Indwelling catheters
• Drainage devices (e.g., ureteral stents, nephrostomy tubes)
• Healthcare-associated UTIs
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Classification
Community-acquired UTI Healthcare-associated UTI
• UTI acquired outside of a • UTI acquired in a healthcare
setting
healthcare setting and/or UTI
• Among the most
that manifests within 48 prevalent healthcare-associated
hours of hospital admission infections
• Nosocomial UTI
• Most common: catheter-
associated UTI (CAUTI)
• Can also occur secondary
to urinary tract instrumentation
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Clinical features
• Typical features of cystitis and urethritis include:
• abrupt onset of frequency of micturition and urgency
• burning pain in the urethra during micturition (dysuria)
• suprapubic pain during and after voiding
• intense desire to pass more urine after micturition, due to
spasm of the inflamed bladder wall (strangury)
• urine that may appear cloudy and have an unpleasant
odour
• non-visible or visible haematuria
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In lower UTIs, systemic
symptoms are usually slight
or absent
Clinical pearl!
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DDx of lower UTI
• Urethritis due to sexually transmitted disease, notably
chlamydia
• Urethritis associated with reactive arthritis
• Vaginitis
• Tuberculous cystitis
• Drug-induced cystitis (e.g., cyclophosphamide, NSAIDs)
or radiation-induced cystitis
• Hemorrhagic cystitis
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Clinical features
• Upper urinary tract infection
• Symptoms of lower urinary tract infection (30%)
• Fever, rigors
• Flank pain with guarding and tenderness
• Fatigue/malaise
• Nausea and vomiting
• Hypotension
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Since fever is usually absent in lower
UTIs, the presence of fever and
flank pain should be considered a sign of
more serious infection,
e.g., pyelonephritis
Clinical pearl!
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DDx of upper UTIs
• pyelonephrosis,
• acute appendicitis,
• diverticulitis,
• cholecystitis,
• salpingitis,
• ruptured ovarian cyst or
• ectopic pregnancy
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Pyelonephrosis Vs. perinephric abscess
• In pyelonephrosis due to upper urinary tract
obstruction, patients may become extremely ill, with
fever, leucocytosis and positive blood cultures.
• With a perinephric abscess, there is marked pain and
tenderness, and often bulging of the loin on the
affected side. Urinary symptoms may be absent in
this situation and urine testing negative, containing
neither pus cells nor organisms.
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Investigations
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Investigations
• Urinalysis
• Indications: best initial test for all patients
• Specimen collection method
• Clean-catch midstream sample: thought to reduce
contamination with vaginal or skin flora
• Straight catheterization of the bladder: may be considered if
the risk of contamination is high
• Suprapubic aspiration: no contamination if performed
correctly but rarely used due to its invasive nature
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Use of the UA to diagnose a UTI
• There are no standarized approaches on how to do this.
• The presence of nitrites is the most specific finding and has the
highest positive predictive value.
• However, leukocyte esterase, WBCs and even bacteria on
microscopic exam are not specific and their presence does not
necessarily indicate infection.
• Diagnosis of a UTI needs also to consider the presence of
symptoms and a positive urine culture (if one is done, which is
probably not necessary in young, otherwise healthy women with
typical symptoms)
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In an
otherwise healthy woman with a single
lower urinary tract infection,
urine culture prior to treatment is not
mandatory.
Clinical pearl!
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Investigations
• Urine culture
• Interpretation
• Interpretation of bacterial counts in the urine, and of what is a
‘significant’ culture result, is based on probabilities.
• Cultures are considered positive if either of the following is present:
• Significant bacteriuria: defined as ≥ 105CFU/mL in a clean-catch specimen in
asymptomatic patients
• If the patient has symptoms and there are neutrophils in the urine, a small
number of organisms is significant (≥ 102 CFU/mL in women, ≥
103 CFU/mL in men)
• Any organisms in a specimen obtained by suprapubic aspiration
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In patients with complicated or recurrent urinary
tract infections, a urine culture should be obtained
prior to initiating antibiotic treatment. False
negative results are possible if a culture is obtained
after the patient has received antibiotics.
Clinical pearl!
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Imaging is not routinely
necessary for patients
with uncomplicated lower UTI.
Clinical pearl!
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Management
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Notes & Notes in UTI
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MCQ
• A 28-year-old woman patient who is 13 weeks pregnant presents for
an antenatal clinic appointment. The patient feels embarrassed
when asked to provide a urine sample and produces enough for a
urine dipstick test only which is positive for leukocytes and nitrites.
The patient denies any symptoms. The most appropriate treatment
is:
A. Trimethoprim
B. Quinolone
C. Tetracycline
D. Cephalexin
E. Ampicillin
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UTI in pregnancy
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Treatment of UTI in pregnancy
• Which antibiotics to avoid?
• trimethoprim,
• sulphonamides,
• quinolones and
• tetracyclines.
• Which antibiotics are safe?
• Penicillins and cephalosporins
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MCQ
• A 28-year-old woman patient who is 13 weeks pregnant presents for
an antenatal clinic appointment. The patient feels embarrassed
when asked to provide a urine sample and produces enough for a
urine dipstick test only which is positive for leukocytes and nitrites.
The patient denies any symptoms. The most appropriate treatment
is:
A. Trimethoprim
B. Quinolone
C. Tetracycline
D. Cephalexin
E. Ampicillin
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MCQ
• A 66-year-old woman with poorly controlled type 2 diabetes presents to
accident and emergency with a 2-day history of severe pain in the right
flank, nausea and fevers that come and go. On examination, the patient
appears unwell, sweaty and has visible rigors with a temperature of 38°C.
The patient denies any recent travel. Urine dipstick is positive for protein,
blood, leukocytes and nitrates. A CT scan of the abdomen reveals gas in the
renal parenchyma area. The most likely diagnosis is:
A. Renal stones
B. Renal infarction
C. Diabetic nephropathy
D. Renal TB
E. Pyelonephritis
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Acute pyelonephritis
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Notes in acute pyelonephritis
• Acute renal infection (pyelonephritis) presents as a classic
triad of loin pain, fever and tenderness over the kidneys.
• Renal infection is almost always caused by organisms
ascending from the bladder, and the bacterial profile is the
same as for lower urinary tract infection.
• Rarely acute pyelonephritis can be complicated by:
• Renal or perinephric abscesses
• Papillary necrosis.
• Urosepsis
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Suspect pyelonephritis in any
patient presenting with fevers,
chills, and flank pain, irrespective
of lower urinary tract symptoms.
Clinical pearl!
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Notes in acute pyelonephritis
• Perinephric abscesses is most commonly due to
staphylococci.
• Predisposing factors, such as cysts or renal scarring,
facilitate infection.
• In papillary necrosis, fragments of renal papillary tissue are
passed per urethra and can be identified histologically.
They may cause ureteric obstruction and, if this occurs
bilaterally or in a single kidney, it may lead to AKI.
• Predisposing factors include diabetes mellitus, chronic
urinary obstruction, analgesic nephropathy and sickle-cell
disease.
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Rule out urosepsis in
elderly patients
with altered mental status!
Clinical pearl!
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Notes in acute pyelonephritis
• A necrotising form of pyelonephritis with gas formation,
‘emphysematous pyelonephritis’, is occasionally seen in
patients with diabetes mellitus.
• Xanthogranulomatous pyelonephritis is a chronic infection
that can resemble renal cell cancer.
• It is usually associated with obstruction, is characterised by
accumulation of foamy macrophages and generally
requires nephrectomy.
• Infection of cysts in polycystic kidney disease calls for
prolonged antibiotic treatment.
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Notes in acute pyelonephritis
• If complicated infection is suspected or response to
treatment is not prompt, urine should be re-cultured
and renal tract ultrasound performed to exclude
urinary tract obstruction or a perinephric collection.
• If obstruction is present, drainage by a percutaneous
nephrostomy or ureteric stent should be considered.
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MCQ
• A 66-year-old woman with poorly controlled type 2 diabetes presents to
accident and emergency with a 2-day history of severe pain in the right
flank, nausea and fevers that come and go. On examination, the patient
appears unwell, sweaty and has visible rigors with a temperature of 38°C.
The patient denies any recent travel. Urine dipstick is positive for protein,
blood, leukocytes and nitrates. A CT scan of the abdomen reveals gas in the
renal parenchyma area. The most likely diagnosis is:
A. Renal stones
B. Renal infarction
C. Diabetic nephropathy
D. Renal TB
E. Pyelonephritis
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Persistent or recurrent
UTI
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Notes in persistent or recurrent UTI
• If the causative organism persists on repeat culture
despite treatment, or if there is reinfection with any
organism after an interval, then an underlying cause is
more likely to be present and more detailed investigation
is justified.
• In women, recurrent infections are common and
investigation is justified only if infections are frequent
(three or more per year) or unusually severe.
• Recurrent UTI, particularly in the presence of an
underlying cause, may result in permanent renal damage,
whereas uncomplicated infections rarely (if ever) do so
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Notes in persistent or recurrent UTI
• If an underlying cause cannot be treated, suppressive
antibiotic therapy can be used to prevent recurrence and
reduce the risk of sepsis and renal damage.
• Urine should be cultured at regular intervals; a regimen of two
or three antibiotics in sequence, rotating every 6 months, is
often use in an attempt to reduce the emergence of resistant
organisms.
• Trimethoprim or nitrofurantion is recommended for
prophylaxis.
• Alternative antibiotics include cefalexin, co-amoxiclav and
ciprofloxacin, but these should be avoided if possible because
of adverse effects and the generation of resistance.
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Notes in persistent or recurrent UTI
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MCQ
• In which of the following situations would you consider
treating an asymptomatic patient identified to have > 105
E. coli/mL urine?
A. Healthy 14 year old girl
B. 24 year old woman, normal ultrasound and flexible
cystoscopy in the past
C. 32 year old pregnant woman
D. 67 year old man with a urethral catheter in situ
E. 78 year old woman with a ureteric stent in place for
retroperitoneal fibrosis
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Asymptomatic
bacteriuria
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Notes in asymptomatic bacteriuria
• This is defined as more than 105 organisms/mL in the
urine of apparently healthy asymptomatic patients.
• Statistics about ASB:
• 1% of children under the age of 1 year,
• 1% of schoolgirls,
• 0.03% of schoolboys and men,
• 3% of non-pregnant adult women and 5% of pregnant women
have asymptomatic bacteriuria.
• It is increasingly common in those aged over 65
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There is no
evidence that this condition causes renal
scarring in adults who are not pregnant
and have a normal urinary tract, and, in
general, treatment is not indicated.
Clinical pearl!
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Treatment is required in
infants, pregnant women and
those with urinary tract
abnormalities.
Clinical pearl!
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Catheter-related bacteriuria
• In patients with a urinary catheter, bacteriuria increases
the risk of Gram-negative bacteraemia five-fold.
• Bacteriuria is common, however, and almost universal
during long-term catheterisation.
• Treatment is usually avoided in asymptomatic patients, as
this may promote antibiotic resistance.
• Careful sterile insertion technique is important and the
catheter should be removed as soon as it is not required.
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MCQ
• In which of the following situations would you consider
treating an asymptomatic patient identified to have > 105
E. coli/mL urine?
A. Healthy 14 year old girl
B. 24 year old woman, normal ultrasound and flexible
cystoscopy in the past
C. 32 year old pregnant woman
D. 67 year old man with a urethral catheter in situ
E. 78 year old woman with a ureteric stent in place for
retroperitoneal fibrosis
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Urethral syndrome
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Urethral syndrome
• Usually female, have symptoms suggestive of urethritis and
cystitis but no bacteria are cultured from the urine.
• Possible explanations include:
• infection with organisms not readily cultured by ordinary
methods (such as Chlamydia and certain anaerobes),
• intermittent or low-count bacteriuria,
• reaction to toiletries or disinfectants,
• symptoms related to sexual intercourse, or
• post-menopausal atrophic vaginitis.
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MCQ
• A 42-year-old diabetic Asian male complains of dysuria, increased
urinary frequency and general malaise for the past six months. In
the last few days, he has noticed blood in the urine. Examination of
the urine shows the presence of neutrophils with no organisms
detected on urine culture. The most likely diagnosis is:
A. Tuberculosis
B. Renal cell cancer
C. Diabetic nephropathy
D. Bladder cancer
E. Nephritic syndrome
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Urinary tract TB
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Other types of TB
• Tuberculous meningitis → Neurology
• Pericardial TB → cardiology
• Cutaneous TB → dermatology
• Gastrointestinal TB → GI surgery
• Genitouriary TB → Nephrology and urology
• Pott disease → Orthopedics
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Notes in urinary tract TB
• Tuberculosis of the kidney and renal tract is secondary
to tuberculosis elsewhere and is the result of blood-
borne infection.
• Initially, lesions develop in the renal cortex; these
may ulcerate into the renal pelvis and involve the
ureters, bladder, epididymis, seminal vesicles and
prostate.
• Calcification in the kidney and stricture formation in
the ureter are typical.
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Notes in urinary tract TB
• Clinical features may include
• symptoms of bladder involvement (frequency, dysuria);
• haematuria (sometimes macroscopic);
• malaise, fever, night sweats, lassitude and weight loss;
• Loin pain;
• associated genital disease; and
• chronic renal failure as a result of urinary tract
obstruction or destruction of kidney tissue.
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Notes in urinary tract TB
• Investigations may include
• Neutrophils are present in the urine but routine urine
culture may be negative (‘sterile pyuria’).
• Special techniques of microscopy and culture may be
required to identify tubercle bacilli and are most usefully
performed on early morning urine specimens.
• Bladder involvement should be assessed by cystoscopy.
• Radiology of the urinary tract and a chest X-ray to look
for pulmonary tuberculosis are mandatory
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Notes in urinary tract TB
• Anti-tuberculous chemotherapy follows standard
regimens.
• Surgery to relieve urinary tract obstruction or to
remove a very severely infected kidney may be
required.
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MCQ
• A 42-year-old diabetic Asian male complains of dysuria, increased
urinary frequency and general malaise for the past six months. In
the last few days, he has noticed blood in the urine. Examination of
the urine shows the presence of neutrophils with no organisms
detected on urine culture. The most likely diagnosis is:
A. Tuberculosis
B. Renal cell cancer
C. Diabetic nephropathy
D. Bladder cancer
E. Nephritic syndrome
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A high index of suspicion is
required to diagnose
urinart tract TB!
Clinical pearl!
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THANK YOU!
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