1. urine culture
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Dr.Ayham Abu Laila

2. Pathophysiology of urinary tract infection
Ascending route of infection is the most common
Hospital infection associated with lower urinary tract instrumentation (catheterization, cystoscopy)
Once in the bladder uropathogens multiply, then pass up the ureters (especially if vesicoureteral reflux present) to the renal pelvis and parenchyma
Source of uropathogens: enteric bacteria
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Dr.Ayham Abu Laila

3. Urinary tract infection more common in women than men
short female urethra
distention and turbulent flow that washes urethral organisms into the bladder during micturition
close proximity to perianal areas
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Dr.Ayham Abu Laila

4. Pathophysiology of urinary tract infection
Cystitis: (lower urinary tract infection)
Pyelonephritis: infection of the kidney with acute suppurative inflammation of the
pelvis,
medullary and cortical tubules,
corticomedullary intersititum
Urosepsis: bacteremia due to pyelonephritis
Papillary necrosis
Sloughing of necrotic pyramids
Perinephric abscess
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Dr.Ayham Abu Laila

5. Risk factors in complicated urinary tract infection
Indwelling catheters
Urinary calculi
Neurogenic bladder
Prostatic enlargement
Uterine prolapse
Urologic instrumentation or surgery
Renal transplantation
Diabetes mellitus
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6. Common Uropathogens Escherichia coli
Other Enterobacteriaceae (Klebsiella, Enterobacter, Proteus, Citrobacter)
Pseudomonas aeruginosa
Enterococcus
Staphylococcus saprophyticus
Staphylococcus aureus
Associated with staphylococcemia
Streptococcus agalactiae (group B)
Denotes vaginal colonization in pregnant women
Candida
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Dr.Ayham Abu Laila

7. Uncommon Uropathogens
Corynebacterium urealyticum
Haemophilus influenzae and H. parainfluenzae
Blastomyces dermatitidis
Neisseria gonorrhaeae
Mycobacterium tuberculosis
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Dr.Ayham Abu Laila

8. Urinary Tract Specimens
First-voided morning urine optimal (generally bacteria have been proliferating in bladder urine for several hours)
Midstream urine specimens (initially voided urine contains urethral commensals)
Indwelling catheters (freshly placed, urine aspirated by needle inserted into catheter) (Foley catheter tips not acceptable)
Straight catheter specimens
Suprapubic aspirates (infants or children, recovery of anaerobes)
Cystoscopic collection of urine
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Dr.Ayham Abu Laila

9. Specimen collection Male:
1. If not circumcised, draw back the foreskin.
2. Begin to urinate, but pass the first portion into the toilet.
3. Collect the mid-portion of urine into the container, and pass the excess into the toilet.
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Dr.Ayham Abu Laila

10. 1. Squat over the toilet and separate the labia with one hand.
Female:
1. Squat over the toilet and separate the labia with one hand.
2. Void the first portion of urine into the toilet.
3. Collect the mid-portion of urine into the container and pass the excess into the toilet.
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Dr.Ayham Abu Laila

11. 1. Clean the external genitals.
Infants:
- Have ready: Clean, preferably sterile container of appropriate size or a plastic bag, cotton wool or gauze pads, hand warm soapy water.
1. Clean the external genitals.
2. Give the child as much liquid as possible just prior
to the collection.
3. Seat the child on the lap of the mother, nurse or
ward attendant.
4. Collect as much urine as possible in the container or
plastic bag when the
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Dr.Ayham Abu Laila

12. Collection of Urine Specimens
Urine collected in sterile specimen container must be processed within hours, or refrigerated and processed within 24 hours
Urine collected in sterile specimen container with borate preservative should be processed within 24 hours (no refrigeration required)
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Dr.Ayham Abu Laila

13. Catheterized Urine Cleanse periurethral area with soap and water
DO NOT RECONTAMINATE
Insert catheter into bladder
Discard initial urine
Collect specimen in sterile cup
Chronic indwelling Foley catheter
Clamp tubing below junction (or port)
Disinfect with alcohol
Insert needle (on syringe) through port or catheter wall and aspirate
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Dr.Ayham Abu Laila

14. Suprapubic Aspiration
BE CERTAIN BLADDER IS FULL - PALPATE OR PERCUSS
Prep skin with alcohol or iodine
Anesthetize with lidocaine
Introduce needle 2.0 cm above symphysis
Aspirate 20 ml for culture
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Dr.Ayham Abu Laila

15. Suprapubic Aspiration
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Dr.Ayham Abu Laila

16. Inoculation of Urine
Inoculation of urine for quantitative culture (colony forming units→cfu’s) performed with a calibrated mL and 0.01 mL plastic or wire loop
Sheep blood agar (SBA) utilized for quantitative urine culture
With ml loop, 1 colony on SBA equivalent to 1,000 cfu’s per mL of urine
With 0.01 ml loop, 1 colony on SBA equivalent to 100 cfu’s per mL of urine
MacConkey agar utilized as selective differential agar for gram-negative bacteria
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Dr.Ayham Abu Laila

17. 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 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 ( cfu’s/mL urine)
Urethral commensals recovered at <104 cfu’s/mL urine
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Dr.Ayham Abu Laila