URINARY TRACT INFECTIONS
by
Dr FARAZ AZIM NIAZ
Consultant Nephrologist
MRCP(UK), SSC-Nephro(KSA)
King Khalid University Hospital, Riyadh
Epidemiology of UTI
Worldwide, 150 million cases / year
90 % cystitis, 10 % pyelonephritis
75 % sporadic
25 % recurrent
2%
complicated
Prevalence of urinary tract
infections (UTI)





almost half of all women 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.
asymptomatic bacteriuria in women ↑with age &
occurs in 2.7%
of
15 - 24 year olds
9.3%
of over 65 year olds
20 - 50% of over 80 year olds
Prevalence of UTIs 2



UTI is rare in young and middle-aged men
& often with catheterisation or urological
procedures.
bacteriuria in elderly men occurs in





10% of those living at home,
20% of those living in nursing homes &
30% of those who are in hospitals
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.
Gender and sexual contact
Infant and children : Male >> female
Adolescent-menopause : Female >> male
Older age : Female = = male
Women: Short ureter
Sexual contact : colonization of pathogens
in bladder
Spermicidal : Change of normal flora
Men (<50) : Prostate infection, anatomical defects ,
Lack of circumcision, homosexuals
Symptomatic Infection
Asymptomatic
bacteriuria
Classification of UTIs
Classification by
Type of UTI
Asymptomatic bacteriuria
Cystitis
Upper / Lower UTi
Pyelonephritis
Symptoms
Symptomatic
Asymptomatic
Recurrence
Sporadic < 1 UTI / 6 m
Recurrent  1 UTI / 6m
Complicating factors
Uncomplicated
Complicated
Urinary Tract Infection- Types
urethritis
cystitis
prostatitis
Lower
pyelonephritis
intrarenal &
perinephric abscess
Upper
UTI- types by complicating factor

Uncomplicated UTi: infection in a
structurally and neurologically normal
urinary tract
Complicated UTI: infection in tract
with functional or structural abnormalities

Complicated or Un-Complicated UTI

Uncomplicated UTI is the one occurring in a
healthy young nonpregnant woman,

& a Complicated UTI is the one occurring
in anyone else.
vs
Pathophysiology
Host protective factors inUTI

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
Immune responses in UTI



Submucosal IgA-producing plasma cells in
bacterial cystitis
IgM & IgG antibodies produced against bacterial
antigens
Protective role of antibodies unclear, may limit
damage within the kidney & prevent persistent
colonization & thus recurrence of infection
Host Factors Complicating
Bacteriuria
Facilitate bacteriuria Residual bladder urine after voiding
Turbulent urethral flow(stricture)
Foreign bodies
Atrophic vaginal mucosa
Vesico-ureteral reflux
Worse prognosis of UTIs Childhood pyelonephritis
Diabetic nephropathy
Malignant hypertension
Chronic pyelonephritis
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
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
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)
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
Pathogenesis of UTIs:
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
Pathogenesis of UTIs - 2
Predisposing Conditions- contd


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


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
Terminology of UTI

Cystitis: localized infection of the bladder

Prostatitis: localized infection of the prostate = lower UTI

Pyelonephritis: infection of the kidney with acute
inflammation of the pelvis, medullary and cortical tubules, &
intersititum = upper UTI

Urosepsis: bacteremia ( in blood) due to pyelonephritis

Perinephric abscess: associated with obstruction of an
infected kidney with abscess formation in the peri-nephric
space due to extension of infection across the renal capsule
Clinical Symptoms of UTI
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
Urethritis


?
Acute dysuria, frequency
Suspect sexually transmitted pathogens,
no hematuria, no suprapubic pain,
new sexual partner, cervicitis
Cystitis





Symptoms: frequency, dysuria, urgency,
suprapubic pain
Cloudy, malodorous urine (nonspecific)
Leukocyte esterase positive = pyuria
Nitrite positive (but not always)
WBC (2-5 with sx) and bacteria on urine
microscopy
Cystitis
Acute
Pyelonephritis
Pyelonephritis


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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
?
Pyelonephritis

Complications:
sepsis, papillary necrosis, abscess,
ureteral obstruction
↓renal function if scarring,
in pregnancy – ↑incidence of preterm labor
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
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
Diagnosis algorithm
Symptomatic
patient
Uncomplicated cystitis
in a woman,
no risk factors
not a relapse
Yes
No
No
Bacterial culture,
"on the spot" testing
to confirm diagnosis
Typical symptoms,
< 2 infections / year,
patient familiar with
her illness
Yes
Start
treatment
based on
results
Antibiotic
therapy
Dipstick Methods
pH, Sp.Gravity, protein, glucose, blood, ketone,
Leukocyste esterase +
Pyuria
Nitrite +
Gram(-) bacteriuria
except pseudomonas
FACTS
NITRITE: Screening test for bacteria in urine
Gm –ve bact convert urine nitrate to nitrite
False –ve:
enterococcus, ascorbate, urine <4 hrs
LEUCOCYTE – ESTERASE by
granulocytes
Test threshold is 5 – 15 WBC/HPF
False –ve in : glycosuria, high sp. Gravity, cephalexin,
tetracyclin, ↑oxalates, vaginal debris
Microscopic Examination
Pyuria: WBC > 5 / HPF in spun urine
Bacteriuria
> 105 cfu/ml
Diagnosis of UTI
Urinalysis :
Leukocyte esterase : On Dipstick exam
Nitrate nitrite : On Dipstick exam
gram negative bacteria except pseudomonas
• Pyuria :
> 5 WBC /HPF, WBC cast
Bacteriuria : > 105 cfu/ml
Collecting a sample
in adults, mid stream urine (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 hours (any shorter time
will increase the risk of false negative findings)

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
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
Asymptomatic bacteriuria
microbiological diagnosis
Positive Urine culture repeatedly (105 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.
.
Causative agents of UTIs

Escherichia coli




most common
80% of community - acquired
50% of hospital-acquired
Others:




enterococci
Staphylococcus saprophyticus and
klebsiella
pseudomonas and proteus are more rare
% of Organisms in UTI
% of types of Organisms in UTI
Localization of UTI
No definite standard method
Ultrasonography
IVP
Abdominal CT / MRI
Tc-99m DMSA renal scan
A
B
C
D
CT images at different levels –> hypodense areas of ?pyelonehritis
T1 MRI- hypointense area
T2 MRI- hyperintense area
Axial MRI- hyperintense area
MRI – Fluid (abscess) in lower pole
Emphysematous Pyelonehritis: (a) CT – air in wall of U.B (b) Plain X ray- mottling in UB
(A gas forming infection of renal parenchyma & perinephric tissues )
Xanthogranulomatous Pyelonephritis
Enlarged cystic areas + a stone in the pelvis
Tc-99m DMSA
Renal Scan
DDx
Scar
Renal infarction
↓Renal cortical
uptake
Indentation at upper pole
Sterile Pyuria- causes
Pyuria in the absence of bacterial infection
Recent UTI treated with antibiotics
Glucocorticoid therapy
Acute febrile episode
Cyclophosphamide
Pregnancy
Renal transplant rejection
Genitourinary tract trauma
Prostatitis and cystourethritis
Renal T.B.
Therapy in UTIs - 1
Acute uncomplicated
cystitis: in women

patient with typical symptoms, not belonging to any of
the risk groups, is treated without laboratory
investigations

if the symptoms are atypical, a strip test urinalysis may
be carried out to support diagnosis

if the strip test is negative, the urine should be cultured
and other reasons for the symptoms should be
considered
Treatments of UTI - options
Lower UTI (Cystitis) : in women
3-7 days course of antibiotics ( short is preferable)
•Trimethoprin/SMX = 1st choice
•Cephalosporines ( Cefpodoxime)/ Nitrofurantoin
•Fluoroquinolone ( ciprofloxacin, Norfloxacin etc)
 Lower UTI (Cystitis) : in men
Longer course for 7 days
•TMP/SMX
• Flouroquinolones
•B-lactams( Augmentin) or Nitrofurantoin: not recommended
If no improvement→ consider Prostatis
ORAL
Treatment of pyelonephritisUncomplicated pyelonephritis:
Mild to moderate pts can be treated orally as outpatient with
either a
 quinolone ( ciprofloxacin or levofloxacin)
 sulpha-trimethoprim for
Duration : 7-14 days course of antibiotics

B- lactams, Nitrofurantoin: not favoured
If Amoxil: then give for 14 days.

Inpatient management is appropriate in the following :
1.
2.
3.
4.
Severe illness with high fevers, pain, and marked debility
Pt unable to maintain oral hydration or take oral medications
Pregnancy
Concerns about patient compliance
Oral drugs
Treatment of pyelonephritis-Complicated
ie :progression to renal corticomedullary abscess,
perinephric abscess, emphysematous pyelonephritis,
or papillary necrosis
Consider underlying anatomic or functional
abnormalities
An unwell patient should be admitted to hospital

Parentral treatment is commenced with either


Cephalosporines i.v. ( ceftriaxone ) or
fluoroquinolone orally/ I.V

& change to oral, when response is obvious
Note: Antibiotics alone may not be successful unless
underlying conditions are corrected
I.V Drugs
Prevention of UTI
Recurrent UTI
Women with > 3 episodes of UTI per year
Avoidance of spermicidal or diaphragm
frequent and complete voiding
Immediate voiding after sexual contact
Good hydration
Antibiotics after sexual contact
Low dose antibiotics prophylaxis
Prophylaxis of recurrent UTI with
antimicrobial agents



prophylaxis should be considered when
more than 3 infections per year or
2 in 6 months
prophylaxis to continue for 6 months
if infections recur after prophylactic
treatment, the prophylaxis is recommenced for 6 – 12 months (D)
Pregnancy and UTI
Incidence of UTI in pregnant women: 2-8 %
20-30 % of pregnant women with
asymptomatic bacteriuria :
 Upper UTI (pyelonephritis)
in 2nd-3rd trimester b/c Ureteral dilatation, reflux
Effects ofUTI in pregnancy : Increased incidence
of fetal death and growth retardation
UTI in Pregnancy - TREATMENT
Flouroqinolones are CONTRA-INDICATED
•Low urinary tract infection :
7 day course antibiotics
Ampicillin, cephalosporine
Pyelonephritis:
2-4 weeks course antibiotics
Cephalosporins, extended spectrum penicillins
Parenteral treatment
Thereafter, follow-up urine culture, monthly
Asymptimatic bacteriuria
Antibiotics Tx & f/u
Treatment during pregnancy



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
asymptomatic bacteriuria & cystitis are treated in the
same way
Requires longer tx of 7-14 days
Cephalosporin, nitrofurantoin, augmentin,
sulfonamides (do not use near term b/c risk of
kernicterus
single-dose treatment is not recommended
due to foetal risk fluoroquinolones should be
avoided during the whole of pregnancy, and
sulphatrimethoprim during the latter part of
pregnancy
Treatment of UTI in diabetics
Cystitis in diabetics


drugs of choice for initial treatment are same as for uncomplicated
UTI
antibiotic treatment must always be based on the results of
urine culture

treatment to continue for 7 days
Acute pyelonephritis in diabetics



treatment is the same as for uncomplicated pyelonephritis
consider urological imaging earlier than normal, if there is no
response to appropriately chosen medication
the causative agents of recurrent UTI’s in diabetics are often
unusual, resistant microbes (species of pseudomonas, enterococci
and enterobacter) and various candida species.
Treatment of Complicated UTI





Catheter - related
Ampicillin/gentamycin or Tazocyn or
ticaricillin/clav or imipenem or meropenem x
2-3 weeks
Switch to PO FQ or TMP/SMX when possible
Rule out obstruction
Watch out for enterococci and pseudomonas
UTI in CHILDREN- Needs prompt
recognition & treatment





Symptoms, non-specific,so difficult to
distinguish between upper & lower,
however, in < 2 yrs old child
History of UTI
Temperature >40ºC
most helpful
Suprapubic tenderness
Lack of circumcision
UTI in CHILDREN- in verbal children




Abdominal pain
Back pain
Dysuria, frequency, or both
New onset urinary incontinence
SAMPLING of Urine – difficult ( catheter, suprapubic)
Diagnosis: in usual ways.
Therapy : Dose of AB as per Weight
UTIs in men

a UTI in men can be associated with either acute or chronic
bacterial prostatitis

prostatitis or epididymitis may play a part


particularly in febrile UTI
it is advisable to palpate both the prostate and scrotum
chronic bacterial prostatitis, or at least the retention of
bacteria in the prostatic ducts, should be suspected in
relapses with the same causative bacteria
UTIs in men 2
Afebrile lower urinary tract infection in men:


if the infection is not associated with urinary stricture or
prostatitis,it is treated with the same drugs as cystitis in
women, but the treatment should continue for 7 - 10 days
nitrofurantoin should not be used in men as adequate
prostatic concentrations are not achieved (D)
Febrile urinary tract infection in men is treated with


a long course of antibiotics with good prostatic and
epididymal penetration
first choice: a fluoroquinolone for 2 weeks
UTIs in men 3
UTI in men associated with acute bacterial
prostatitis


treatment for 4 - 6 weeks (depending how quickly patient
responds to treatment)
to be followed up with low dose prophylaxis with e.g.
trimethoprim or nitrofurantoin
Chronic bacterial prostatitis



recurrent UTI’s and calcifications in prostate
oral quinolones for 2 – 3 months (D)
to be followed up with prophylactic medication
Lower UTIs in children



treatment principles are the same as for
adults
little evidence to support short term treatment
in children (C)
drugs of choice



nitrofurantoin 5 mg/kg/day or
trimethoprim 8 mg/kg/day
treatment to continue for 5 days (C)
Probable lower UTI with generalised
symptoms in children



treated so that any possible infection of the kidney is also
covered, i.e. with antibiotics with high tissue penetrability
oral medication acceptable
drugs of choice
 sulphatrimethoprim (trimethoprim 8 mg/kg/day)

cefalexin 30 - 50 mg/kg/day in 3 divided doses
cefuroxime axetil 20 mg/kg/day in 2 divided doses or
mecillinam 20 - 40 mg/kg/day in 3 divided doses

treatment to continue for 7 days (C)


Treatment of pyelonephritis in
children



all infants with febrile UTI should be admitted to hospital
drugs of choice
 cefuroxime (100 mg/kg/day in 3 divided doses) or
 ceftriaxone (80 mg/kg/day daily)
 intravenous therapy until obvious response
 when obvious response to treatment is observed, medication
is changed over to oral until the total course of treatment, i.e.
10 days, is completed
follow-up treatment according to culture and sensitivity
results, with an antibiotic with good tissue penetrability (e.g.
sulphatrimethoprim or a cephalosporin)
Treatment

?
Uncomp. cystitis with less than 48 hours of
sx, non-pregnant, usu. 3 days tx sufficient





Bactrim DS, Septra DS
Cipro or other FQ (avoid in preg.)
Nitrofurantoin (7 days)
Augmentin
Bladder analgesis, Pyridium
Asymptomatic
Bacteriuria





?
105 org/mL growth
Empiric treatment of all asymptomatic bacteriuria
(ASB) in pregnancy. Screening at first visit.
ASB if untreated = inc. PTD and LBW, 20-30%
develop pyelo.
Do TOC in 2 weeks and each trimester.
Screen Sickle cell trait each trimester. Twofold
inc. risk of ASB
Asymptomatic Bacteriuria


Treatment failures: repeat tx based on
sensitivities for 1 week, then prophylactic
therapy for remainder of pregnancy
Prophylaxis: Nitrofurantoin, Ampicillin,
TMP/SMX
Treatment of Pyelonephritis -Outpatient



Uncomp. Nonpreg pyelo
Primary – any FQ x 7 days, cipro
Alt. -- Augmentin, TMP/SMX, or oral CSP for
14 days
Treatment of
Pyelonephritis – Inpatient ?




Treat IV until patient is afebrile 24-48 hours. Then,
complete 2 week course with PO meds
Use FQ or amp/gent or ceftriaxone or piperacillin
If no improvement on IV, consider imaging studies to
look for abscess or obstruction
All pregnant patients with pyelo get inpatient tx,
appropriate IV antibiotics immediately
Predisposing conditions






Neurogenic bladder: dysfunction or bladder
diverticulum (incomplete emptying)
Age - Postmenopausal women with uterine or
bladder prolapse (incomplete emptying), lack of
estrogen, decreased normal flora, concomitant
medical conditions such as DM
Vesicoureteral reflux
Bacterial virulence
Genetics
Change in urine nutrients, DM, gout
Predisposing conditions to UTI

Female



Short urethra, proximity to anus, termination beneath labia
Sexual activity
Pregnancy


2-3% have UTI in preg, 20-30% with asx bacteriuria  may
lead to pyelonephritis
Increased risk of pyelo = decreased ureteral tone,
decreased ureteral peristalsis, temp. incomp of
vesicoureteral valves
Symptoms of UTIs 1
Cystitis:
 typical symptoms include frequency and burning
sensation when passing urine.
Pyelonephritis:
 only some patients have difficulties in micturition
 temperature (> 38oC) and flank or back pain
 nausea in the elderly or sudden collapse in
health status (”off-legs”)
Symptoms of UTIs 2




incontinence or offensive urine in the elderly
should not be considered as UTI as such; even
though they may be indicative signs of an infection
almost any signs of infection in infants may be
indicative of a UTI (C)
in a small child a temperature alone, without any
other signs of an infection, should raise a
suspicion of a UTI
UTI in children and the elderly may manifest itself
as incontinence or retention.
Complicated UTIs are those occurring in…

Men

Children

Pregnancy

People with suspected pyelonephritis

People with recurrent UTI

Failed antibiotic treatment or persistent symptoms

Catheterised patients

Hospital-acquired infections

Recent urinary tract instrumentation

People with abnormalities of genitourinary tract

People with renal impairment and

People with impaired host defences
Catheter-Associated UTI





10-15% of hosp. pts with catheter develop
bacteriuria
Risk of infection is 3-5% per day of catheterization
UTI after one-time bladder cath approx. 2%
Gram neg. bacteremia- most significant complication
Greater antimicrobial resistance
Urine Culture Study
Significant bacteriuria
Midstream clean technique:
105 CFU/ml
Suprapubic puncture, catheter collected urine:
102 CFU/ml
Women with symptomatic cystitis
Pyuria +102 CFU/ ml
Symptomatic pyelonephritis patients
Pyuria +104 CFU/ml
Diagnosis of UTIs 1

No need to do any urinalysis, if a female
patient, who does not belong to any of the risk
groups, clearly has occasional cystitis based on
her symptoms

Urine microscopy is not usually necessary to
diagnose cystitis
Diagnosis of UTIs 2

Bacterial culture of urine should be carried out in all
cases, except in uncomplicated cystitis, even though
the results will not be available when medication is
commenced (B)

In early pregnancy bacterial culture should be carried out
in all pregnant women if only to diagnose asymptomatic
bacteriuria (A)

In adult febrile infections with generalised symptoms,
and in children’s infections, C-reactive protein (CRP)
concentration above 40 mg/l is suggestive of a kidney
infection (C)
Interpretation of Urine Cultures:
General Guidelines




A single species of Enterobacteriaceae recovered at >105
cfu’s/mL urine: with patients symptomatic for urinary tract
infection, 95% probability of true bacteriuria
A single species of Enterobacteriaceae recovered at 104-105
cfu’s/mL urine: with patients symptomatic for urinary tract
infection, 33% probability of true bacteriuira
Gram-positive, fungal, and fastidious uropathogens often
present in lower numbers (104-105 cfu’s/mL urine)
Urethral commensals recovered at <104 cfu’s/mL urine
Commensal Microflora of the Urethra






Coagulase-negative staphylococci (except
S. saprophyticus)
Viridans and non-hemolytic streptococci
Lactobacilli
Diphtheroids (Corynebacterium except C.
urealyticum)
Saprophytic Neisseria
Anaerobic bacteria
Common Bacterial Contaminants
Staphylococcus epidermidis
Corynebacteria(diphtheroids)
Lactobacillus
Gardnerella vaginalis
Anaerobic bacteria
Urine culture is not helpful for women with
uncomplicated lower urinary tract infections as it
does not improve outcomes.

In women with classical presentation of uncomplicated UTI,
treatment can begin based on the strength of clinical
presentation.

In women with dysuria and vaginal symptoms consider
both a UTI and STIs.

A dipstick positive to nitrites or leukocytes has a
probability of a UTI of about 80%

A dipstick negative to both nitrites and leukocytes, has a
probability of a UTI of about 20%.
Contents
When is urine culture helpful?
Urine culture should be performed for:
1.
Women with a UTI with complicating features
2.
All pregnant women
3.
Men with suspected UTI
4.
Suspected acute pyelonephritis
5.
Prostatitis
Contents
Complicating features in women include:
•
Abnormal urinary tract e.g. stone, reflux, catheter,
•
Impaired host defences e.g. pregnancy, diabetes,
immunosupression,
•
Impaired renal function,
•
Suspicion of pyelonephritis,
•
More than three UTIs in one year, or
•
UTI recurrence within two weeks.
Contents
Urine culture is recommended for pregnant
women
Women with asymptomatic bacteriuria in early pregnancy
have a 20-30 fold increased risk of developing
pyelonephritis, premature delivery and low birth weight
infants.
All pregnant women should be screened for asymptomatic
bacteriuria at 12-16 weeks gestation.
If bacteriuria is detected by screening, the patient should be
treated and a urine culture performed monthly throughout
the pregnancy
Contents
Urine culture is indicated for lower UTI in Men
All UTIs in men are considered complicated, therefore a
urine culture is indicated, even if the urine dipstick is
negative.
Contents
A urine culture is indicated when acute pyelonephritis is
suspected
Dipstick testing of the urine may be useful if clinical findings are
equivocal
Antibiotics should be commenced while waiting for culture
results
Post-treatment urine cultures are recommended one to two
weeks after antibiotic therapy
Contents
Screening for asymptomatic bacteriuria
Screening for asymptomatic bacteriuria is not
in:
recommended
1.
Non pregnant women
2.
Elderly people
3.
People with indwelling urinary catheter.
4.
People with spinal cord injuries.
The prevalence of asymptomatic bacteriuria varies from 1-5% to
100% in selected population groups.
Asymptomatic bacteriuria is a microbiological diagnosis based on the
isolation of a specified count of bacteria in the absence of signs of
UTI.
Contents
Causative Microbes of APN-I
Microorganism
No(%)
E.Coli
191 (88)
Klebsiella pneumoniae
8
(3.7)
Staphylococcus species
8
(3.7)
Enterococcus species
7
(3.2)
Acinetobacter iwoffii
1
(0.5)
Enterobacter aerogenes
1
(0.5)
Xanthomonas maltophilia
1
(0.5)
민 등, 대한신장학회지 1998
Microorganisms in Urine(OPD)
Microorganisms
Escherichia coli
Enterococcus faecalis
Klebsiella pneumoniae ssp
Enterococcus faecium
Staphylococcus aureus
Pseudomonas aeruginosa
Proteus mirabilis
Enterobacter cloacae
Klebsiella oxytoca
%
51
13
6
3
3
3
2
2
1
CNUH, 2003
Antibiotics Sensitivity for E. Coli
Antibiotics
Ampicillin
Trimethoprim/Sulpha
Cefazolin
Amikacin
Imipenam
Ciprofloxacin
Gentamycine
No(%)
27.3
43.9
82.0
98.3
98.4
76.1
79.8
이 등, 대한신장학회지 2002
Single-dose therapy

single-dose therapy is slightly less effective than conventional
therapy

effective in infections caused by E. coli, but less so in S.
saprophyticus infections
recommended particularly when practical reasons warrant its use
(e.g. self-care)
Preparations:
 phosphomycin 3 g
 norfloxacin 800 mg
 ciprofloxacin 500 - 750 mg
 ofloxacin 200 mg as a single dose


Antimicrobial therapy in UTIs 2
Reserve drugs:


Quinolones (norfloxacin, ofloxacin or ciprofloxacin) for 3 days
 if first choice drugs are not suitable or
 if the infection has not responded to first choice drugs or
 recurrent infection within 4 weeks
 if there is a relapse, urine must be cultured and the treatment
should be continued for 7 days
In special cases:
 cefalexin or cefadroxil for 5 days (if the above are
contraindicated)
 sulphatrimethoprim for 3 days (particularly if the level of
infection is unclear)
 amoxicillin for 5 days (particularly in enterococcal infections)
Treatment
of Recurrent uncomplicated UTI



3 or more episodes in one year, 2 in 6 months
Bactrim DS ( or septra DS) QD for 3-6 months
- once infection eradicated, self-admin.,Single dose
at symptom onset or one DS tab post-coitus
Measures for prevention:
voiding after intercourse,
good hydration,
frequent and complete voiding
Underlying Conditions
Diseases
Percents(%)
Diabetes mellitus
56 (49.6)
Urinary tract stone
22 (19.5)
Congenital anomaly
7(6.2)
Renal cyst
6(5.3)
Pregnancy
5(4.4)
Neurogenic bladder
5(4.4)
Vesico-Ureteral reflux
4(3.5)
민 등, 대한신장학회지, 1998
Drugs of choice in UTI prophylaxis
First choice:


trimethoprim 100 mg in the evenings
nitrofurantoin 50 - 75 mg in the evenings
Second choice:




methenamine hippurate 1 g twice daily
norfloxacin 200 mg daily or on 3 evenings per week
nitrofurantoin (not if serum creatinine is above 150 μmol/l)
quinolones (in cases where there is no response with other
prophylactic medication or tolerance to other medications is
poor)
During pregnancy:



nitrofurantoin 50 mg daily or
methenamine hippurate 1 g daily for the rest of the pregnancy
particularly if recurrent bacteriuria is diagnosed in early
pregnancy
Un-Complicated or complicated UTI
‘Uncomplicated’ UTI are

occasional lower UTI in women
with no predisposing factors
‘Complicated’ infections are all other UTIs
including lower UTIs in




men
Children
pregnant women
catheter-induced infections
UTI - also categorized into



Non-catheter associated
(community- acquired)
Catheter associated (hospital- acquired)
Any category may be
symptomatic or asymtomatic
Causative organisms of
AcutePyelonephritis
Microorganism
No (%)
E.Coli
122 (91.7)
Enterococcus spp
4
(3.0)
Pseudomonas spp
2
(1.5)
S. viridans
2
(1.5)
Proteus
1
(0.8)
Coag.N.Staph
2
(1.5)
Not isolated
113
이 등, 대한신장학회지 2002
Microorganisms in Urine (ER)
Microorganisms
Escherichia coli
Enterococcus faecalis
Klebsiella pneumoniae ssp
Alcaligenes xylosoxidans
Burkholderia cepacia
Staphylococcus aureus
Proteus mirabilis
Enterococcus faecium
Enterobacter cloacae
%
51
9
7
5
5
3
3
3
2
CNUH, 2003
Xanthogranulomatous Pyelonephritis
Mass-like lesion of Ch.PN b/c obstruction due to infected renal stones