2. Urinary Tract Infection
• Presence of infection (pathogenic
microorganism) in the urinary tract system
TWO GENERAL ANATOMIC CATEGORIES OF ACUTE
UTI:
Lower tract infections (urethritis, cystitits)-
superficial infection
Upper tract infection (prostitis, infrarenal &
perinephric abscesses) – signify tissue invasion
3. Major Clinical Forms of UTI:
• Uncomplicated UTI – occurs in a normal host without
structural of functional abnormality of the urinary tract
• Complicated UTI- associated with structured or
functional abnormality
FACTORS SUGGESTING UNCOMPLICATED UTI:
• Young, sexually active, non-pregnant female
• Recent onset of dysuria, frequency, & other symptoms
• No recent GU instrumentation
• No recent GU instrumentation
• No recent antibiotic treatment
• No GU abnormality
4. UTI is subdivided epidemiolically into:
• Catheter- associated or nosocomial
• Non – catheter associated or community acquired
-very common
-1-3% among schoolgirls
• -increasing incidence with the onset of sexual
activity
• Acute symptomatic & asymptomatic bacteriuria-
common among young women (20-50 yrs) but
unusual in males under 50 years of age
• Asymptomatic bacteriuria - > common among
elderly men & women ( 40 – 50% in some studies)
5. Etiology
• E.coli causes -80% of acute infections without
catheter, urologic abnormality, or calculi
(uncomplicated UTI)
• Nosocomial infections – Proteus, Klebsiella,
Enterobacter, Serratia, & Pseudomonas
• Proteus & Kelbsiella – predispose to stone
formation & more frequently isolated patients
with calculi
– By virtue urease production ( Proteus ) &
extracellular slime & polysaccharide production
( Klebsiella)
6. • Gram + plays a lesser role
-staph, saprophyticus=10-15% of acute Ss UTI in young
females
-enterococci ocassionally cause uncomplicated cystitis
-enerococci and staph aureus- commonly cause
infection in patients w/ renal stones or previous
instrumentation or surgery
-isolation of staph aureus arouse suspicion of
bacteremic infxn of the kidney
1/2 of women w/ dysuria and frequency have
eitherinsignificant bacteriuria or complete sterile culture
=of these ¾ have pyuria and ½ (-) pyuria
7. • Women w/ acute urinary sx, pyuria and sterile urine--
- ST urethritis producing agent such as chlamydia
trachomatis, neisseria gonorrhea and herpes simplex
virus (young, sexually active women with new sexual
partners)
• Non bacterial pathogens:
-ureaplasma urealyticum
-mycoplasma hominis
-adenoviruses(often in epidemics)
-fungal infxn like candida
=mycobacterium
8. Pathogenesis
Routes of infection
-ascending infection
-hematogenous
-lymphatics
Ascending infection:
uropathogens (fecal flora)- colonization of
vaginal introitus- enter the urethra- ascend to
the urinary bladder- stimulate host responses
(dysuria, frequency, urgency, pyuria)
9. • Vaginal introitus and distal urethra normally colonized by
diphtherois, strep species, lactobacilli and staph species
• Gm (-) organisms- normal colonizers of the bowel
-noted to colonize the introitus, periurethral skin, and distal
urethra before and during episodes of bacteriuria–
probably due to alteration of normal vaginal flora by
antibiotics, other genital factors or contraceptives (esp
spermicide like diaphragm/ cervical cap/ condoms)
-loss of lactobacilli in vaginal flora appears to facilitate
colonization by E.coli
-urethral massage during intercourse--- facilitate
periurethral entry to the bladder
10. Factors affecting Severity of symptoms
1. Size of inoculum of introduced bacteria
2. Virulence factor of the infecting strain
3. Host resistance or defense mechanism
• High urea concentration & high
osmolarity of bladder urine inhibits or
kills bacteria
11. Conditions affecting pathogenesis:
1. Gender & sexuality – women > prone to
colonization of gm (-) bacilli due to:
a.) proximity of the urethra to the anus
b.) short length of urethra ( ~4cm)
c.) urethral termination beneath the labia
- Sexual intercourse causes introduction of
bacteria to bladder in women – voiding after
intercourse decreases the risk of cystitis
- UTI uncommon in men <50 y.o.
12. 2. Pregnancy – 2-8% have UTI
- 20 -30% with asymptomatic bacteriuria
subsequently developed pyelonephritis
- Predisposition to UTI due to:
a.) decrease ureteral tone
b.) decrease ureteral peristalsis
c.) temporary incompetence of vesicoureteral valves
3. Obstruction – tumor, stricture, stone, prostatic
enlargement
4. Neurogenic bladder dysfunction – due to
interference of nerve supply to the bladder –
prolonged stasis of urine in the bladder
13. 5. Vesicoureteral reflux – reflux of urine from bladder
into ureters and sometimes into renal pelvis
- Occurs with increase vesical pressure during
voiding
- Dx by voiding cystourethrogram
- Due to anatomically impaired VU junction
- Marked reflux – renal damage
6. Bacterial virulence factor
- Fimbriae ( E.coli and Proteus) – adheres to
uroepithelial cells which is the critical first step in
the initiation of the infection
- Not all strains of E.coli are capable of causing UTI
- E.coli produces hemolysin & aerobactin – resistant
to bactericidal action of human serum
14. • 7.Genetic factors
- Maternal Hx of UTI common among women
with recurrent UTI
- The number & type of uroepithelial cells to
which bacteria may attack are in part genetically
determined
- P + Erythrocytes mediators attachment of P
fimbriae-- pyelonephritis
16. Catheter – associated UTI’s
• 10 – 15% of hospitalized patients with urethral
catheter
• Risk of infection is 3-5% day of catherization
• Common pathogens are E.Coli, Proteus,
Pseudomonas, Klebsiella, Serratia,
Staphylococcus, Enterococci , & Candida
(markedly related to antimicrobial resistance)
• Minimal Sx, no fever & often resolves after
withdrawal of catheter
• 1-2% may develop gm (-) bacteremia
17. Factors associated with inc risk of catheter associated UTI
- female sex
- prolonged catheterization
- severe underlying dse.
- disconnection of the catheter and drainage
tube, other types of faulty catheter care
-lack of systemic antimicrobial treatment
Routes of infection
migration through the column of urine in the catheter
lumen (intraluminal route) or up the mucous sheath
outside the catheter (periurethral route).
18. PROSTATITIS
Acute bacterial prostatitis
- may occur spontaneously or associated with indwelling catheter
- Fever, chills, dysuria, and tense or boggy, extremely tender prostate
- Avoid vigorous prostatic massage to produce secretions--- may lead
to bacteremia
- Gm (-) pathogens(E.coli and Klebsiella)
Chronic Bacterial Prostatitis
- Considered in men w/ recurrent bacteriuria
- Often asymptomatic between episodes
- Prostate usually normal on palpation
19. Diagnosis
• Urinalysis
• Urine culture- gold standard
Sx patient—100,000 bact/ml or > usually
present but smaller # of bacteria (100-10,000)
may signify infection
Asymptomatic patients--- 100,000 bact/ml
or more of a single specie in 2 urine specimens
Suprapubic aspirate--- 100 bact/ml or
more or bacteriuria of any degree
20. Treatment
Forms of treatment
- short course therapy (single day or 3 days tx)
-conventional therapy
-long term therapy
-single day tx associated w/ more recurrence
- unCx cystitis- short course tx
- males w/ UTI- conventional tx
- Cx UTI- conventional or long term tx
- asymptomatic bacteriuria- Tx give to high risk px
- prostatitis- long term tx
-antibiotic- depending on the etiologic agent (> gm-org)
21. Prognosis
Uncomplicated cystitis/ pyelonephritis
- complete resolution of sx w/ tx
-repeated episodes of cystitis– always reinfxn
Acute unCx pyelonephritis- rare progresses torenal
dysfunction and CRD
- repeated episodes of pyelonephritis—often
represent relapse
Repeated Sx UTI with obstruction, neurogenic
bladder, structural renal dse or DM--- progress to
CRD
