3. • A spectrum of diseases caused by
microbial invasion of GU tract that
extends from renal cortex of the
kidney to the urethral meatus
• An extremely common medical problem
• Commonest sample received
15. Risk factors for UTI
Females Males
All ages Previous UTI
Uroligical instrumentation or surgery
Urethral catheterization
Urinary tract obstruction
Neurogenic bladder
Renal transplantation
Lack of circumcision
Uroligical instrumentation or
surgery
Urethral catheterization
Urinary tract obstruction
Neurogenic bladder
Renal transplantation
HomosexualsAdults Sexual intercourse
Spermicidal contraceptive jellies
Diaphragm use
Pregnancy
Lower socioeconomic group
Diabetes
Sickle cell trait in pregnancy
HIV +
Diabetes
HIV+
Older age Estrogen deficiency
Loss of vaginal lactobacilli
Bladder prolapse
Functional & mental
impairment
Prostatic enlargement
Condom catheter drainage
17. Uropathogenic strains
• Not all E coli cause UTI
• Serogroups O1, O2, O4, O6, O7,O8, O75, O150 &
O18ab
• Certain O,K & H serogroups also correlate with
clinical severity
18. Recognized virulence factors include
• Adhesins →pili or fimbriae
• Nonfilamentous proteins in outer membrane
• P fimbriae
• K antigen (K1, K5, K12)
• α & β hemolysins
• Aerobactin
• Siderphores
• Endotoxins
• Sat protein
• Motility
19. • Proteus adhere produce→ →
urease hydrolyze urea increases pH of→ →
urine direct toxicity to kidney cells→
stimulates formation of kidney stones→
• Similar findings with Klebsiella spp.
• S. saprophyticus adheres better than
S.aureus or S. epidermidis
• invade superficial epithelial cells →
replicate large foci triggers host→ →
response exfoliation of superficial cells→
23. Specimen Patient preparation Special instructions
Clean voided mid stream
urine
Females: clean area with
soap & water; hold labia
apart & begin voiding in
commode; after passing
several ml, collect MSU
Males: clean glans with
soap & water, rinse with
water, retract the
foreskin, after passing
several ml, collect MSU
24. Specimen Patient preparation Special instructions
Suprapubic aspirate Disinfect skin Needle aspiration above
the symphysis pubis
through abdominal wall
into full bladder
25. Specimen Patient preparation Special instructions
Indwelling catheter
(Foley)
Disinfect catheter
Collection port
Aspirate 5-10ml of urine
with needle & syringe
26. Specimen Patient preparation Special instructions
Straight catheter (in &
out)
Clean urethral area (soap
& water) & rinse with
water
Insert catheter Into
bladder; allow 1st
15ml to
pass; collect remainder
27. • 1st
urine passed in morning → most concentrated
• Renal failure/young child → few milliliters of urine
• Label (date & time of collection, name & number)
• Explain to patient
• Deliver promptly
• Delay unavoidable → store in refrigerator at 4°C
• Or transport in refrigerated container
• Or collection & transport in container with boric acid at
a final bacteriostatic conc. 1.8%
• Samples not so treated and delayed more than 5hrs
should be discarded & doctor should be informed
28. Tuberculosis of urinary tract
• 1st
urine passed in the day (early morning
urine; EMU)
• 3 to 6 consecutive days
• 3 complete EMU should be sent to laboratory
• Individual specimens refrigerated pending
process
29. Urethritis
• Initial flow rather than the mid stream
collected
Prostatitis
• Prostatic secretions
• Urethral urine & MSU obtained before &
after massage
31. Urine specimen
Wet film Culture
Microscopy
Gram stain
Non-specific
biochemical tests
Gross examination
BA
MacConkey
LF NLF
Colony charc. H’lysis
α,β,NHPin head, pin point
Identification
AST
32. Appearance Possible Cause
Cloudy
Urine has an unpleasant
smell & contains WBCs
•Bacterial urinary infection
Red & cloudy
Due to red cells
•Urinary schistosomiais
•Bacterial infection
Brown & cloudy → Due to
haemoglobin
•Blackwater fever
•Intravascular Haemolysis
Yellow-brown, green brown
→ Due to bilirubin
•Acute viral hepatitis
•Obstructive jaundice
Yellow-orange → Due to
urobilin, i.e. oxidized
urobilinogen
•Haemolysis
•Hepatocellular jaundice
Milky-white→ Due to chyle •Bancroftian filariasis
37. Examination of a gram stained smear
• Both uncentrifuged & centrifuged specimens
• 1 or more bacterial cells/OIF x at least 5
fields (uncentrifuged) ≥ 105
CFU/ml
• If negative → smear sediment → bacterial cells
indicate < 105
CFU/ml
38. Non-specific biochemical tests
1. Griess nitrite test
2. Leucocyte esterase test
3. Catalase test
4. Triphenyltetrazolium chloride (TTC)
5. Glucose test paper method
51. Wet mount/gram stain fungal cells or hyphae or fungal infection suspected→
Few drops of sediment
Fungal bottle containing Emmons modification of SDA & SDA with actidione
Incubate @ room t° upto 2wks
BHIA x room t°x 4wks
(Diamorphic fungi suspected)
Low colony count as significant as high
53. Urine
50ml x 3600g x 30mnts
2ml sediment
Decontamination x oxalic acid x 30mnts
Inoculate
BACTEC medium LJ medium
Incubate x 37°C ≥ 6wks
Growth +
Confirmation by AFB smear
Incubate x 37°C ≥ 6wks
Growth +
Confirmation by AFB smear
55. Significant bacteriuria
• MSU most easily & commonly collected sample
• Contaminants → very bacteria which cause UTI
• Isolation not proof of UTI
• Proof of UTI → demonstration of pathogens in
freshly voided urine in No. > those likely to result
from contamination
• Edward Kass suggested that this number, taken to
indicate significant bacteriuria, is about 105
/ml
• In properly collected sample contamination accounts
for less than 104
/ml & usually for less than 103
/ml
56. General interpretation guidelines for urine cultures
Result Specific specimen type/
associated clinical
condition, if known
Workup
≥104
CFU/ml of a single
potential pathogen or of
each of two potential
pathogens
MSU/ Pyelonephritis,
acute cystitis,
asymptomatic bacteriuria
or catheterized urines
Complete
≥103
CFU/ml of a single
potential pathogen
MSU/symptomatic males
or catheterized urines or
acute urethral syndrome
Complete
≥three organisms with no
predominating organism
MSU or catheterized
urines
None. Because of possible
contamination, ask for
another specimen
Either two or three
organisms with
predominant growth of one
organism type & <104
CFU/ml of other
organisms
MSU Complete workup for
predominant organism.
description of other
organisms
≥102
CFU/ml of any number
of organism
Suprapubic aspirates complete
57. Oxoid Chromogenic UTI Clarity Agar
• Chromogenic media → aid diagnosis
• Distinguish b/w colonies of
different species on a culture plate.
• Good growth of the main UTI
pathogens
• Prevents swarming of Proteus
• Coliforms dark blue/purple→
colonies
• Enterococci blue/turquoise→
colonies
• Improved recovery of S aureus
• Correct presumptive
identification of Citrobacter freundii
• Results 16-24 hours
• Ready poured plates
• Or dehydrated culture medium
58. Automated screening methods
Automated Principle
Bioluminescence
UTI screen
Detects bacterial ATP utilizing
enzymatic bioluminescent
reaction of ATP with luciferin &
lucifrase
Photometry Vitek If significant no. of organisms
present grow in medium to a→
detectable conc. Utilizing
photometry
Colorimetric particle filtration
Bac-T-Screen
Automated combination testing
for both bacteria & WBCs by
membrane filtration & detection
utilizing
Safranin O dye