This document defines urinary tract infections (UTIs), lists common risk factors, and discusses causative organisms. UTIs are defined as significant bacteriuria of 105 CFU/ml or more in a urine sample. Risk factors include being female, older age, obstruction of the urinary tract, instrumentation like catheterization, and certain medical conditions like diabetes or immunosuppression. The most common causative organism is Escherichia coli, while other gram-negative bacteria and some gram-positive bacteria can also cause UTIs.

1. SARAL LAMICHHANE
ROLL-61
Urinary Tract
Infections(UTI)
(Definition, Risk Factors & Organisms)
Gandaki Medical College, Nepal
Correlation Seminar- 2013

2. 2
To define UTI,
To list out the predisposing conditions of
UTI,
To enumerate the organisms causing
UTI.

3. Definition
:
3
Presence of significant bacteriuria, 105 or
more CFU/ml of properly collected ‘clean-
catch’ midstream sample of urine. [or more
than 100 CFU/ml in symptomatic patient
with accompanying pyuria (>10 WBCs/ml)]
Microbial invasion of any tissue of urinary
tract from renal cortex to the urethral
meatus that either ascend from urethra or
spread to kidney from bloodstream.

4. Types:
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 Based on the anatomic site:
1. Lower tract infection:
a. Urethritis
b. Cystitis
c. Prostatitis
2. Upper tract infection:
a. Pyelonephritis (Acute & Chronic)
b. Acute Pyelitis
 Based on the clinical setting:
1. Uncomplicated UTI
2. Complicated UTI

5. Predisposing conditions of
UTI:
5
 Gender : Increased incidence in females
(F:M=30:1)
About 40% females suffer from UTI at least once at
some point in their life.
Age: Increases with age (Equally high for M/F if
65yrs+)
 Obstruction: Stones, urethral stricture, tumors &
bladder diverticula cause stasis increasing UTI.
In males, Benign Prostatic Hypertrophy (BPH) &
lack of circumcision are risks for UTI.
Instrumentation , Catheterization causes

6. 6

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Functional Abnormalities:
 Neurogenic bladder dysfunction: Due to spinal
cord injury, tabes dorsalis, multiple sclerosis,
diabetes.
 Vesicoureteral Reflux : Reflux of urine from
bladder upto ureter & renal pelvis during voiding
or incresed bladder pressure.
 Bladder prolapse, Genital prolapse
 Diabetes Mellitus:Bladder dysfunction,Immune
dysfunct.
Immunosupression : HIV AIDS, Steroids,
Cytotoxic Immunosupressive drugs increase UTI
Antecedent antimicrobial therapy

8. For females :
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 Pregnancy: Increased incidence of UTI
-Decreased ureteral tone & peristalsis
Stasis
-Incompetence of vesicourethral valves
 Sexual Activity: Increases with sexual activity
-Higher in female sex workers
-Honeymoon cystitis
 Menopause: Increases incidence (loss of
lactobacillus in vaginal mucosa decreases
acidity)
 Uterine prolapse: Increases incidence
 Contraceptives Use: Spermicidals with

9. ???Why more incidence in
females???
9
Shorter length of urethra
Proximity of vagina to anus
Urethral trauma during sex
Pregnancy state in females
Use of spermicidals with
diaphragms or cervical caps

10. Causative
Organisms:
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BACTERIA:
• Gram negative: • Gram positive:
Escherichia coli (80%) Staph. saprophyticus
Klebsiella spp. ---Adults(13-40 yr)
Proteus spp. Enterococcus (S.
fecalis)
Providencia spp. Staph. epidermidis
Pseudomonas Staph. aureus
Enterobacter
Serratia
• Rare causes:
Salmonella spp., M. tuberculosis, Chlamydia,

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• VIRUSES : • FUNGI :
Adenoviruses Candida spp.
Cytomegalovirus Cryptococcus
• PROTOZOA:
Trichomonas vaginalis

12. TAKE HOME MESSAGE…….
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UTI is the presence of significant bacteriuria.
i.e. 105 or more CFU/ml in midstream urine sample
 Upper UTI- Pyelonephritis, Acute Pyelitis
Lower UTI- Urethritis, Cystitis, Prostatitis
 The risk of UTI is several times higher in females
due to shorter length of urethra.
 The major organism causing UTI is Escherichia
coli.

13. References
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o Harrison’s Principles of Internal Medicine
o A Textbook of Microbiology, P. Chakraborty
o A Handbook of Clinical Microbiology, Bharat
Mani Pokhrel
o www.mayoclinic.com
o www.clinicalkey.com
o Classnotes
o Pictures from google.com

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ANY
QUERIES???

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Diabetes= neve supply=neutrophil
Prolapse= incomplete voiding
Catheter=Pseudom. Candida .staph
epidermidis