Urinary Tract Infections

1. URINARY TRACT INFECTIONS
Presented by
Bibek Bhandari
IInd
batch

2. Epidemiology of UTI
Worldwide, 150 million cases / yearWorldwide, 150 million cases / year
90 % cystitis, 10 % pyelonephritis
75 % sporadic
25 % recurrent
2 % complicated

3. Prevalence of urinary tract
infections (UTI)
 almost half of all womenwomen will have at least one
UTI in their lives.
 the risk of UTI in women increases after
menopause
 after a UTI: 20 - 40 % will have a recurrence
 recurring infections are usually reinfections.

4.  UTI is rare in young and middle-aged menmen & often
with catheterisation or urological procedures.
 Urinary catheter increases the risk almost ten-fold in
hospitalised patients and those in other care homes.
 Pyelonephritis is common in patients who have
been catheterised for over a month.

5. Gender and sexual contact
Infant and children : Male >> femaleInfant and children : Male >> female
Adolescent-menopause : Female >> maleAdolescent-menopause : Female >> male
Older age : Female = = maleOlder age : Female = = male
Women: Short ureterWomen: Short ureter
Sexual contact : colonization of pathogensSexual contact : colonization of pathogens
in bladderin bladder
Spermicidal : Change of normal floraSpermicidal : Change of normal flora
Men (<50)Men (<50) : Prostate infection, anatomical defects ,: Prostate infection, anatomical defects ,
Lack of circumcision, homosexualsLack of circumcision, homosexuals

6. Classification by
Type of UTI
Upper / Lower UTI Pyelonephritis
Asymptomatic bacteriuria
Cystitis
Symptoms Symptomatic
Asymptomatic
Recurrence Sporadic < 1 UTI / 6 m
Recurrent ≥ 1 UTI / 6m
Complicating factors Uncomplicated
Complicated
Classification of UTIs

7. Urinary Tract Infection- Types
Urethritis
Cystitis Lower
Prostatitis
Pyelonephritis
Intrarenal & Upper
Perinephric abscess

8. vs
Pathophysiology

9. Host protective factors in UTI
 Flushing mechanism of micturition
 Acid pH of urine (4.6- 6) anti-bacterial
 Acid vaginal pH (3.5-4.5)) suppresses colonization
 Urinary Tamm-Horsefall protein (secreted by
ascending loop of Henle) & blocks E. coli
 Chemotactic factors - interleukin-8

10. Facilitate bacteriuriaFacilitate bacteriuria Residual bladder urine after voiding
Turbulent urethral flow(stricture)
Foreign bodies
Atrophic vaginal mucosa
Vesico-ureteral reflux
Worse prognosis of UTIsWorse prognosis of UTIs Childhood pyelonephritis
Diabetic nephropathy
Malignant hypertension
Chronic pyelonephritis
Host Factors Complicating
Bacteriuria

11. Bacterial virulence factors in UTI
 Escherichia coli strains expressing O-antigens
cause high proportion of infections
 Capsular antigens of E. coli associated with clinical
severity (antiphagocytic)
 P-fimbriae enhance attachment of E. coli) to
uroepithelial cells
 Motile bacteria ascend the ureter against urine flow

12. Bacterial virulence factors in UTI
 Bacterial urease (Proteus) splits urea →NH4 ion
alkalinizes urine with loss of acid pH → stone
formation → obstruction & survivial of bacteria
within stones resisting eradication
 Gram-negative endotoxin decreases ureteral
peristalsis
 Hemolysin damages renal tubular epithelium &
promotes invasive infection
 Aerobactin of E. coli promote iron accumulation for
bacterial replication

14. Pathogenesis of UTI
 Ascending route most common
 Colonization of urethra and peri-urethral tissue is the initial
event
 More in women than men due to short female urethra ,so
urethral organisms enter bladder during micturition &
in close proximity to perianal areas
 Once in the bladder , multiply, then pass up the ureters (esp. if
vesico-ureteral reflux) to the renal pelvis & parenchyma
 Hospital infection associated with lower urinary tract
instrumentation (catheterization, cystoscopy)

15. Pathogenesis of UTI- blood borne
 Hematogenous seeding less frequent than
ascending infection
 Kidney a common site of abscess formation in
Staphylococcus aureus bacteremia, less often in
candidemia, rarely with gram-negative bacteremia
 Hematogenous seeding of kidney also occurs with
Salmonella (typhoid) and Mycobacterium
tuberculosis
 Source of uropathogens: enteric bacteria

16. Pathogenesis of UTI: Risk Factors
 ↓ resistance of mucous membranes (e.g. in
menopause)
 sexual intercourse
 disturbances in ureteral functioning
 in children the re-entering of urine back into the ureters
(vesicoureteral reflux),
 Uterine prolapse
 Diabetes

17. Pathogenesis of UTIs
Predisposing Conditions- contdPredisposing Conditions- contd
 Benign prostatic hypertrophy
 Any illness, eg diabetes, affecting the
emptying -Neurogenic Bladder
 Spinal injury →disturbances in bladder
emptying or urinary catheter)
 Stones
 Catheterisation & other urological
procedures
 Renal Transplantation

18. Types of UTI Typical Symptoms & Signs
Cystitis Frequent voiding, suprapubic pain
Burning micturition
Hematuria, cloudy urine
Pyelonephritis Fever chills, flank pains, N/Vomiting
Cystitis Sx ±
Urosepsis Fever- chills
Shock
Clinical Symptoms of UTI

19. Urethritis
 Acute dysuria, frequency
 Suspect sexually transmitted pathogens,
no hematuria, no suprapubic pain,
new sexual partner, cervicitis

20. Cystitis
 Symptoms: frequency, dysuria, urgency,
suprapubic pain
 Cloudy, mal-odorous urine (nonspecific)
 Pyuria
 WBC (2-5 with symptoms) and bacteria on
urine microscopy

21. Cystitis

22. Acute
Pyelonephritis

23. Pyelonephritis
 Fever, chills
 Nausea/Vomiting, diarrhea, tachycardia,
 Costo-vertebral angleTenderness or
deep abdominal tenderness
 Leukocytosis
 Urine microscopy: Pyuria + WBC casts,
bacteria & hematuria
 Possibly signs of Gram negative sepsis

24. Pyelonephritis
 Complications:
Sepsis
Papillary necrosis
Abscess,
Ureteral obstruction
↓ renal function if scarring,
In pregnancy – ↑incidence of preterm labor

25. Diagnosis of UTI
 History
 Physical exam
 Lab parameters:
 Urinalysis with microscopy for WBC, bacteria
 Urine culture with sensitivities
 Diagnose acute uncomplicated cystitis in women based on
Hx, PE, and UA alone, no need for culture to treat

26. Diagnosis
 Urinalysis
 Leukocyte-esterase positive. = pyuria
 Nitrite positive from urease producing bacteria
eg proteus (but not always)
 Microscopy – WBC ( > 5 in pt with symptoms)
-- Bacteria

27. Collecting a sample
 in adults, mid stream urine (MSU)(MSU) sample usually
reliably represents the urine in the bladder.
 samples from urinary bags or bedpans should not
be used as they invariably will be contaminated
 the most reliable sample is obtained via a
suprapubic puncture
 urine in bladder >4 hoursurine in bladder >4 hours (any shorter time
will increase the risk of false negative findings)

29. Diagnosis- interpretation
 Urine culture
 105
colonies per mL considered standard for
diagnosis - but misses up to 50%
 Now, 103
to 104
accepted as significant if patient
symptomatic
 if several bacterial strains are grown on culture;
contamination of the sample is the likely cause
 Sensitivities for better tailoring of therapy

30. Significant bacteriuria
Clinical status or methods of
sampling
Significant
concentration
(microbes / ml)
MSU; symptomatic patient or urine in
bladder <4 h
>103
MSU; urine in bladder >4 h >104-5
Male patient, catheter specimen sample >103
Female patient, catheter specimen sample >104
Asymptomatic bacteriuria >105
Suprapubic puncture sample any growth

31. Positive Urine culture repeatedly (10Positive Urine culture repeatedly (1055
cfu/ml)cfu/ml)
in the absence of signs of UTI
 pyuria does not affect interpretation
 Investige & treat asymptomatic bacteriuria
→ only in pregnant women
Its prevalence varies from 1-5% to 100%
in selected population groups.
.
Asymptomatic bacteriuria
microbiological diagnosis

32.  Escherichia coliEscherichia coli
 most common
 80% of community - acquired
 50% of hospital-acquired
 Others:
 enterococcienterococci
 Staphylococcus saprophyticusStaphylococcus saprophyticus and
 klebsiellaklebsiella
 pseudomonaspseudomonas and proteusproteus are more rare
Causative agents of UTIs

33. % of types of Organisms in UTI

34. Diagnostic Flowchart for evaluatingDiagnostic Flowchart for evaluating
Patients with UTIPatients with UTI

37. Antibiotic Regimen for UTI

38. Prevention of UTIPrevention of UTI
Recurrent UTI
>3 episodes of UTI per year or >2 in 6 months
Avoidance of spermicidal or diaphragm
Frequent and complete voiding
Immediate voiding after sexual contact
Good hydration
Low dose antibiotics prophylaxis

39.  Prophylaxis should be considered when
more thanmore than 3 infections per year or3 infections per year or
2 in 6 months
 Prophylaxis to continue for 6 months
 If infections recur after prophylactic
treatment, the prophylaxis is re-
commenced for 6 – 12 months (D)(D)
Prophylaxis of recurrent UTI with
antimicrobial agents

41. THANKYOU