This document discusses urinary tract infections (UTIs). It defines UTIs as infections of the urinary system from the kidneys to the bladder. UTIs are generally caused by bacteria like E. coli entering the urinary tract. Factors like female anatomy, sexual activity, and catheters can predispose individuals to UTIs. UTIs are classified as uncomplicated or complicated depending on patient risk factors. Symptoms include urinary problems and in severe cases fever. Diagnosis involves urine tests and cultures. Treatment differs based on infection type but generally involves antibiotics like trimethoprim-sulfamethoxazole over 3-7 days. Prevention focuses on hygiene and prophylaxis in recurrent cases.

1. URINARY TRACT
INFECTION

2. 1. Urinary tract infections (UTIs) refer
to an infection of any part of the urinary
system from kidney to bladder.
2. UTIs are generally defined as the
presence of characteristic
symptoms (e.g. dysuria, frequency) and
significant bacteriuria (presence of
bacteria in urine).
3. Significant bacteriuria is defined as >
105colony forming units (CFU)/ml.
4. In the absence of symptoms, this
level of bacteriuria is termed
asymptomatic bacteriuria.

3. CLASSIFICATION
UTIs can be further categorised depending on
the location of infection (e.g. upper or lower) or
the presence of co-morbidities (e.g. complicated or
uncomplicated).
Upper UTI: infection of the kidney
(pyelonephritis).
Lower UTI: infection of the bladder (cystitis).
Uncomplicated UTI: if occurring in healthy non-
pregnant adult women.
Complicated UTI: the presence of factors that
increase the risk of treatment failure (e.g diabetes,
structural abnormalities, catheter and other devices
+/- men).

5. PATHOGENS
Bacteria: usually
caused by an ascending
bacterial infection from
the urethra
Enterobacteriaceae (gra
m-negative rods)
Escherichia coli: in ∼
80% of UTIs
Proteus mirabilis: ureas
e-producing → causes
alkaline urine with
an ammonia smell
Klebsiella pneumoniae
&
Enterobacter species
Others
Staphylococcus
saprophyticus,
Enterococci (e.g.
Enterococcus
faecalis),
Ureaplasma
urealyticum
Viruses:
Adenoviruses can
cause haemorrhagic
cystitis in children
and
immunocompromised
patients.
Yeast:
rare;
usually Candida
species

6. Predisposing
factors
Female sex: Women are anatomically
predisposed because their urethra is
shorter and the anal and genital regions
are in close proximity, making it more
likely that bacteria might spread from
the anal region and colonize the vagina.

7. Sexual intercourse
• Bacteria may enter the urethra from the genital and anal regions, hence the
term honeymoon cystitis.
• Diaphragm and spermicide use disturbs the vaginal flora, further increasing the risk of
UTIs.
Catheter-associated urinary tract infection (CAUTI): caused by indwelling
urinary catheters; most common cause of iatrogenic or nosocomial urinary tract infection
Host-dependent factors
• Structural or functional abnormalities of the urinary tract (e.g., BPH, vesicouretera
reflux, urinary bladder diverticulum, neurogenic bladder, calculi or stones)
• Pregnancy
• Diabetes mellitus
• Immunocompromise
• Uncircumcised males
• Chronic constipation in toddlers

8. TYPE:
Asymptomatic bacteriuria: presence
of significant bacteriuria without
symptoms

9. Uncomplicated
UTI
Immunocompetent, premenopausal women that are neither pregnant
nor have any condition that predisposes them to an increased risk of
infection.
Complicated UTI Any condition or comorbidity that may predispose a patient to an
increased risk of infection or failed therapy such as:
 Male patient
 Pregnant women
 Children or postmenopausal women
 Presence of any significant functional or anatomical
abnormalities (e.g., BPH, obstruction, stricture)
 History of urological pathologies (e.g., neurogenic bladder, kidney
cysts, stones)
 History of impaired renal function or renal transplantation
 Diabetes mellitus
 Immunocompromise (e.g., transplant recipients, HIV/AIDS)
 Recent history of any instrumentation (e.g., cystoscopy)
 Recent placement of any medical devices (e.g., urinary
catheter, nephrostomy tubes, or stents)
 Infection with a resistant uropathogen or recent antibiotic use
 UTI that spreads beyond
the bladder (sepsis, pyelonephritis, prostatitis)
Recurrent UTI ≥ 2 infections/6 months
or
≥ 3 infections/year
Nosocomial
urinary tract
infection
 Fourth most common nosocomial infection
 Most commonly caused by indwelling urinary catheters

10. CLINICAL FEATURES:
• Dysuria, frequency, urgency
• Suprapubic pain
• Gross haematuria may be present
• Fever is usually absent in lower UTIs;
therefore, fever and flank pain should be taken as
a sign of more serious infection, such
as pyelonephritis.

11. DIAGNOSTICS
Clinical
• Clinical diagnosis in healthy
women with a typical
presentation
• In patients with an atypical
presentation, urinalysis is the
most important diagnostic test
for cystitis.

12. LABORATORY TESTS
• Dipstick urine test
• Best initial test
• Findings indicative of UTI
• Positive leukocyte esterase
• Positive nitrites
• Urine pH may be > 7 (alkaline)
in Proteus mirabilis infections

13. URINE ANALYSIS
WITH MICROSCOPY
Confirmatory test
Required in children and adolescents
Clean-catch midstream specimen is necessary to
avoid contamination with vaginal or skin flora.
Straight catheterization of the bladder or
suprapubic aspiration can also be performed if a
clean catch cannot be obtained without
contamination (e.g., in children who are not toilet
trained.)
Diagnostic criteria for UTI
Pyuria: ≥5-10 WBC/high power field (hpf)
Bacteriuria: presence of bacteria on Gram
stain (most commonly, gram-negative rods)
Leukocyte casts should be absent in lower UTIs.

14. URINE CULTURE
• Diagnostic criteria for UTI
Significant bacteriuria defined as ≥
105 colony forming units
(CFU)/mL serves to confirm a UTI.
• Any bacteriuria in urine from a
suprapubic aspiration of the bladder is
abnormal.

15. Patients with the following characteristics or risk factors:
• Patients with complicated UTI
• Age older than 65 years
• Use of a diaphragm
• Recent use of antibiotics
Suspected cystitis with the following characteristics:
• Duration of symptoms greater than 7 days
• High suspicion of cystitis with a non-diagnostic urinalysis
• Recurrent UTIs
• Suspicion of pyelonephritis or urosepsis

16. DIAGNOSTIC IMAGING
• Indication: complicated cystitis, suspicion of structural abnormalities
• Ultrasound: allows urinary retention to be ruled out; may also show signs
of pyelonephritis
• Children <24 months with a urinary tract infection should undergo
renal ultrasound in case there is a kidney or urinary tract abnormality
• Cystoscopy: evaluates for unusual findings on urinalysis, stones, reflux, urinary
obstruction, polyps or malignancies, and interstitial cystitis
• CT: investigates possible urinary tract pathologies, such as stones, obstruction,
tumours, cysts, and trauma
• Intravenous pyelogram (IVP): to look for structural abnormalities, mainly
obstructions

17. DIFFERENTIAL
DIAGNOSES

18. Interstitial cystitis (painful bladder syndrome)
• Description: rare, chronic, non infectious cystitis with an unknown etiolog that
causes suprapubic pain and scarring of the bladder wall
• Clinical findings
• Suprapubic pain or discomfort
• Relieved by voiding and worsened by bladder filling (most common feature)
• Other exacerbating factors include sexual activity, exercise, alcohol use, and prolonged sitting
• Urgency and frequency
• Symptoms for at least 6 weeks
• Diagnosis
• Clinical diagnosis after exclusion of other diagnoses
• Urinalysis with microscopy: required to exclude other diagnoses
• Therapy
• Behaviour modification (first-line): avoid triggers, fluid management based on
symptoms, bladder training
• Oral medications (second-line): Amitriptyline is most commonly used and works as
an analgesic and antidepressant.
• Invasive procedures in the bladder (third-line)

19. Other differential diagnoses
Tuberculous cystitis (see urogenital tuberculosis)
Drug-induced cystitis (e.g., cyclophosphamide, NSAIDs) or radiation-
induced cystitis
Other diseases of the bladder (e.g., urolithiasis, bladder cancer, foreign objects)
Vaginitis
Pelvic inflammatory disease (PID)
Prostatitis
Urethritis with sexually transmitted infections (Neisseria gonorrhoeae, Chlamydia
trachomatis, etc.), Candida, or irritants
Trauma
Structural abnormalities of the urethra, e.g., diverticula or strictures

20. TREATMENT

21. Antibiotic therapy of
uncomplicated UTIs
Antibiotic therapy of
complicated UTIs

22. Antibiotic therapy of uncomplicated UTIs

23. Principles of therapy
• Empiric treatment can be given
for uncomplicated cystitis; local resistance
patterns should guide the choice of empiric
therapy.
• Persistent symptoms after 48–72
hours of antibiotic therapy suggest
possible complicated cystitis or necessitate
that empiric therapy be changed.
• Phenazopyridine, a urinary analgesic, can be
used for dysuria for 1–3 days.

24. First-line treatment for acute uncomplicated cystitis in nonpregnant
women
Trimethoprim-sulfamethoxazole (TMP-SMX)
Should be avoided in areas with high resistance (> 20%) or in patients who
have used it within the last 3 months (unless the pathogen is susceptible
to TMP-SMX on culture)
Nitrofurantoin: avoid if patient has renal insufficiency or if pyelonephritis is
suspected
Fosfomycin: avoid in suspected pyelonephritis
Second-line treatment
Fluoroquinolones (e.g., ciprofloxacin, levofloxacin)
Oral cephalosporins (e.g., cefpodoxime, cefdinir)
Penicillin (e.g., amoxicillin-clavulanate)
If treatment fails or symptoms worsen, the patient may be treated
for complicated cystitis.

25. Antibiotic therapy of
complicated UTIs

26. Treatment is extended to 7 days in complicated
cystitis.
• Must be able to reach the prostate in men
sufficiently ; therefore, substances such
as Fosfomycin and nitrofurantoin are not
treatment options.
• Treatment failure or recurrent UTIs in men
warrant a urological workup.
Antibiotics of choice
• Fluoroquinolones (e.g., ciprofloxacin, levo
floxacin)
• Cephalosporin, Fosfomycin, nitrofurantoin
and trimethoprim-sulfamethoxazole are
only used if the pathogen is susceptible.
•

27. Treatment of
recurrent
infections
1. Chemoprophylaxis can be given to
patients with > 2 UTIs per year.
2. Postcoital prophylaxis or at the
onset of initial symptoms with a
single dose of TMP-SMX
3. Continuous prophylaxis with low-
dose TMP-SMX for 6 months.

28. PREVENTION

29. 1. Increased fluid intake
2. Postcoital voiding
3. Intermittent straight catheterization is
preferred in patients with neurogenic
bladder.
4. Intermittent catheterization, instead of
the placement of an indwelling catheter,
also reduces catheter-associated UTIs
5. Prophylaxis in recurrent urinary tract
infections

30. REFERENCES
1.https://www.amboss.com/us/knowledge/
Urinary_tract_infections
2.https://app.pulsenotes.com/medicine/ren
al/notes/urinary-tract-infections
.