Urinary tract infection

1. Urinary tract infection
(UTI)
UoD - college of medicine

2. Contents
Introduction
Classification
Epidemiology
Etiology
Pathogenesis
Risk factors
Clinical features
Investigations
Treatment

3. Introduction
• urinary tract infection (UTI) is an infection in any
part of the urinary system —kidneys, ureters,
bladder and urethra
• UTI may be asymptomatic (subclinical infection)
or symptomatic (disease). Thus, the term UTI
encompasses a variety of clinical entities,
including asymptomatic bacteriuria (ABU),
urethritis, cystitis, prostatitis, and pyelonephritis.

4. • Urinary tract infection (UTI) is a common and
painful human illness that, fortunately, is
rapidly responsive to modern antibiotic
therapy. In the preantibiotic era, UTI caused
significant morbidity.

5. Classification
UTI
Upper
• Acute pyelonephritis
• Chronic pyelonephritis
• Interstitial pyelonephritis
• Renal/ perirenal abscess
Lower
• Cystitis
• Prostatitis
• Urethritis
Both are further divided into complicated and uncomplicated

6. UTI terminology
• Uncomplicated : UTI without underlying renal or
neurologic disaese
• Complicated: UTI with underlying structural,
medical or neurologic disease
• Recurrent: > 3 symptomatic UTIs within 12 months
following clinical therapy
• Reinfection: Recurrent UTI caused by a different
pathogen at any time
• Relapse: recurrent UTI caused by same species
causing original UTI within 2 weeks after therapy

7. Epidemiology
• Except among infants and the elderly, UTI occurs far
more commonly in females than in males.
• During the neonatal period, the incidence of UTI is
slightly higher among males because male infants more
commonly have congenital urinary tract anomalies.
• After 50 years of age, obstruction from prostatic
hypertrophy becomes common in men,
• Between 1 year and ∼50 years of age, UTI and recurrent
UTI are predominantly diseases of females.
• As many as 50–80% of women in the general population
acquire at least one UTI during their lifetime—
uncomplicated cystitis in most cases.

8. Etiology
• In acute uncomplicated cystitis in the United States, the
etiologic agents are highly predictable:
-E. coli accounts for 75–90% of isolates;
-Staphylococcus saprophyticus for 5–15%
-Klebsiella species, Proteus species, Enterococcus
species, Citrobacter species, and others for 5– 10%.
Similar etiologic agents are found in Europe and Brazil.
• The spectrum of agents causing uncomplicated
pyelonephritis is similar, with E. coli predominating.

9. Etiology cont..
• In complicated UTI (e.g., CAUTI), E. coli
remains the predominant organism, but other
aerobic gram-negative rods, such as Klebsiella
species, Proteus species…..etc, also are
frequently isolated.
• Gram-positive bacteria (e.g., enterococci and
Staphylococcus aureus) and yeasts are also
important pathogens in complicated UTI.

10. Pathogenesis
• 4 routes of bacterial entry to
urinary tract:
1) Ascending infection: most common
pathway
2) Blood borne spread: accounts for <2%
of documented UTIs and usually results
from bacteremia caused by relatively
virulent organisms, such as Salmonella
and S. aureus
3)Lymphatogenous spread
4)Direct extension from other organs
f

11. The interplay of host, pathogen, and environmental factors determines whether
tissue invasion and symptomatic infection will ensue

12. • For example, bacteria often enter the bladder after
sexual intercourse, but normal voiding and innate
host defense mechanisms in the bladder eliminate
these organisms.
• Any foreign body in the urinary tract, such as a
urinary catheter or stone, provides an inert surface
for bacterial colonization.
• Abnormal micturition and/or significant residual
urine volume promotes true infection.
• In the simplest of terms, anything that increases
the likelihood of bacteria entering the bladder and
staying there increases the risk of UTI.

14. Clinical features
cystitis and urethritis :
• 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.
• Systemic symptoms are usually
slight or absent.
acute pyelonephritis:
• This is suggested by prominent
systemic symptoms with fever,
rigors, vomiting, hypotension
• loin pain, guarding or
tenderness, and may be an
indication for hospitalisation.
• Only about 30% of patients with
acute pyelonephritis have
associated symptoms of cystitis
or urethritis
Prostatitis
• perineal or suprapubic pain,
• pain on ejaculation
• prostatic tenderness on rectal
examination.

16. Treatment
• Cystitis
Drug Regimen Duration Comment
First choice Trimethoprim
Nitrofurantoin
200 mg BID
50 mg QID
3 days
3 days
7-10 days in men
7-10 days in men
Second
choice
Cefalexin
Ciprofloxacin
Pivmecillinam
250 mg QID
250 mg BID
400 mg TID
3 days
3 days
3 days
7-10 days in men
7-10 days in men
7-10 days in men
In pregnancy Nitrofurantoin
Cefalexin
50 mg QID
250 mg QID
7 days
7 days
Avoid trimethoprim and
quinolones during
pregnancy, avoid
nitrofurantoin at term

17. • Prophylactic therapy
Drug Regimen Duration
First choice Trimethoprim 100 mg at night continuously
Second choice Nitrofurantoin 50 mg at night continuously

18. • Pyelonephritis
Drug Regimen Duration Comment
First choice Cefalexin
Ciprofloxacin
1 g QID
500 mg BID
14 days
7 days
Admit to hospital if no
response within 24 hours
Second choice Gentamicin
cefuroxime
According to renal functioin
and serum level
750-1500mg TID
14 days
14 days
Switch to appropriate
oral agent as soon as
possible

19. • References
• HARRISONS NEPHROLOGY AND ACID BASE BALANCE, 2nd edition
• DAVIDSONS PRINCIPLES AND PRACTICE OF MEDICINE , 23rd edition
• Slideshare website

20. Thank you