Definitions, etiology, epidemiology, classifications, pathogenesis, symptoms and signs and invetigations

1. URINARY TRACT INFECTIONS

2. Definition
• Defined as significant bacteriuria in the setting of symptoms of cystitis
or pyelonephritis.
• Organisms that cause urinary infections are those from the normal
perineal flora mostly.
• Majority of infections - cystitis (bladder infection)

3. Epidemiology

4. Epidemiology…
• Frequency in pregnant women is similar to non-pregnant women.
However, recurrence differs.
• More frequent in women than men.
• Prevalence of asymptomatic bacteriuria in pregnant women 3-12%,
opposed to 4-8% in non-pregnant women.
• As many as 40% cases of asymptomatic bacteriuria may progress to
symptomatic UTIs.

5. Etiology and risk factors
• Escherichia coli causes 70-95% of both upper and lower UTIs.
• Other organisms involved include: Staphylococcus saprophyticus,
Proteus species, Klebsiella species, Enterococcus faecalis, other
Enterobacteriaceae, and yeast.
• In certain sub-groups, other organisms are more common than
others, e.g. - Staphylococcus saprophytcus- in young women
• Complicated UTIs- Mostly nosocomial in nature
• Catheter-related UTIs
•

6. Etiology and risk factors…
• Routine pelvic examinations- e.g. VE, speculum examination
• Sexual intercourse contributes to increased risks
• Age- Especially the elderly women, young women
• Pregnancy.
• Preexisting urinary tract abnormalities and obstructions.
• Post-renal transplant patients
• Candiduria- DM, indwelling urinary catheters, and antibiotic use

9. Classification
• Based on site of infection:
a) Upper UTI- Acute pyelonephritis
b) Lower UTI- Cystitis
- Urethritis
- Asymptomatic bacteriuria

10. Pathogenesis
• 3 mechanisms involved
1. Colonization with ascending spread
2. Hematogenous spread
3. Periurogenital spread
• Involves bacteriological virulence capabilities such as adherence
(adhesins), growth, resistance of host defences.
• Anatomical factors- e.g. the shorter length of the female urethra
allows easier access to the bladder, hypertrophy of the kidneys,
increased glomerular filtration rate, reduced bladder contraction
(especially in pregnancy)
• Glycosuria and increased amino acid excretion.

12. symptoms in UTIs
• Dysuria
• Frequency and urgency
• Hematuria
• Lower abdominal discomfort- bladder fullness sensation,
• Suprapubic tenderness
• Flank pain
• Fevers, chills, and malaise
• Vaginal discharge
• Nausea/vomiting may also present

13. Acute pyelonephritis
• Infection of the kidneys.
• If the defense mechanisms of the lower urinary tract fail, upper tract
or kidney involvement occurs and is termed pyelonephritis.
• Characterized by :
- fever (>380
C), shaking chills (patients may present
with hypothermia (as low as 34O
C)
- flank pain (right side more common than left side)
- nausea/vomiting/anorexia
- frequency and urgency.
- costovertebral angle tenderness
- significant bacteriuria/pyuria

14. Acute pyelonephritis…
• Mostly involves the 2nd and 3rd trimester.
• Risk factors- immunosuppression, tobacco use, sickle cell disease,
sexual intercourse and even late presentation for ANC.
• Physical exam- suprapubic and costovertebral angle tenderness may
be present, flank tenderness upon palpation,
• Diagnosis:
- Urine tests- dipstick urinalysis (wbc), microscopy (cell casts)
- Baseline tests- cbc, u/e/c,
- Imaging- ultra sound, CT-scan, MRI

15. Cystitis
• Includes an inflamed bladder mucosa
• Complicated vs uncomplicated
• Uncomplicated- healthy women with no signs of systemic disease
- Non-pregnant
- No fever, nausea, vomiting or flank pains
- Diagnosis- dipstick urinalysis, no culture or lab tests
needed
- Risk factor- sexual intercourse

16. Cystitis
• Complicated- Females with cormobid medical conditions
- All male patients
- Indwelling catheters
- Urosepsis/hospitalization (nosocomial)

17. Special cases of complicated cystitis
• Catheter related UTI- Generally nonspecific, most patients presenting
with fever and leukocytosis.
• Pyuria- >50 wbc per high power field
• Culture- colony counts 100-10000 CFU/ml.
• Only treat when symptomatic.

18. Cystitis in pregnancy
• Risk factors include: Sexual activity, increasing age and parity, DM,
lower socioeconomic class, a previous history of UTIs, sickle cell
disease, structural abnormalities.
• Cystitis occurs in 0.3-1.3% of pregnancies and is never related to
asymptomatic bacteriuria.
• Recommended to screen for UTIs (especially asymptomatic
bacteriuria) in 1st and 3rd trimester.
•

19. Diagnosis
• History
• Physical examination
• Laboratory
- Urine tests- Dipstick urinalysis, microscopy
• CBC,U/E/C

20. Urethritis
• Inflammation of the urethra, which is multifactorial and characterized
by dysuria with/without urethral discharge or may be asymptomatic.
• Without complication, usually resolves without treatment. However
can result in urethral strictures, stenosis or abscess (rarely).
• Recurrent urethritis- reinfection, failed therapy,
• Mostly involves the sexually active age-group with predominantly N.
gonorrhea.

21. Etiology
• Infectious
1. N. gonorrhea (50-90%)
2. Chlamydia trachomatis
3. Ureaplasma urealyticum
4. Mycoplasma genitalium
5. Trichomonas vaginalis
6. Yeast
7. HSV
• Non-infectious
1. Trauma
2. Urethral stricture
3. Catheterization
4. Chemical irritants
5. Dehydration

22. Classification
• Gonococcal urethritis
• Non-gonococcal- e.g. other bacteria, viral, fungal
• Post-traumatic- e.g. due to trauma, chemical irritants

23. Symptoms of urethritis
• Burning upon urination
• Frequency/urgency
• Hematuria
• Urethral discharge (yellow)
• Itching
• Suprapubic pain
• Dyspareunia (women)

24. Diagnosis
• Physical examination
• Microscopy- vaginal swab smear demonstrating at least 5 leukocytes,
gram staining,
• Urine test- Dipstick urinalysis (demonstrating leukocyte esterase), at
least 10 wbc on microscopy- to exclude cystitis and pyelonephritis.
• Note: All patients suspected/confirmed diagnosis of urethritis should
be tested of N. gonorrhea and Chlamydia trachomatis (culture).
• CBC, U/E/Cs,

25. Complications of UTIs
• Perinephric cellulitis and abscess
• Septic shock
• Respiratory insufficience
• Renal dysfunction
• Hematologic dysfunction- e.g. anemia, thrombocytopenia
• Hypoxic fetal events (due to maternal complications of infections)
• Preeclampsia
• Preterm labor

26. Asymptomatic bacteriuria
• The presence of more than 100,000 organisms/mL in 2 consecutive
urine samples in the absence of declared symptoms.
• Untreated, predispose to cystitis and pyelonephritis in pregnancy.
• Usually in early pregnancy.
• Risk factors- prior UTIs, pre-existing DM, increased parity, and low
socioeconomic status.

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