UTI for MSc Student, SIU

1. Dr. Mahadi Hassan Mahmoud
Assistant Professor of Microbiology

2. Overview
• Definition
• Anotomy of urinary system
• Physiology of urinary system
• Normal flora of urinary system
• Etiology of UTI
• Classification – Lower v.s Upper infection
• Clinical Signs and Symptoms
• Lab diagnosis
• Treatment & prophylaxis

3. Urinary Tract Infection (UTI)

4. Urinary system
Consist of:
• Two kidneys: for section of urine.
• Two ureters: for carry urine from
kidney to bladder.
• Bladder: for urine collection
and storage.
• Urethra: for urine discharge.

5. Definition
–Infection of any component of the
urinary tract including
•Urethritis
•Cystitis
•Pyelonephritis

6. Anatomy of Urinary system

7. Function
1. Excretory system: Urine gets rid of
waste products that result from cell
protein catabolism such as urea, uric
acid and toxins.
2. Maintain balance between water and
substances dissolved in it.
3. Give good picture of physiology of
the body

8. Function
4. First line defense mechanism.
• Flushing of urine (urination).
• PH of the urine.
• Mucus membrane in the urethra

9. Types of UTI
• Urethritis:
Infection of urethra is sexually transmitted
disease, can be a part of UTI in females
(Acute Urethral syndromes), causative
agents. Neisseria gonorrhea, S. pyogens,
Ureoplasma ureolyticus, Chlamydia and T.
vaginalis.

10. Types of UTI
• Cystitis:
Infection of bladder can be caused by E.
coli, S. saprophyticus and proteus.
• Pyelonephritis (infection of kidney):
E. coli, S. saprophyticus, proteus and S.
aureus.

11. Types of UTI
According to anatomical structure can be
divided to:
• Upper UTI:
Kidneys and ureters.
• Lower UTI:
Bladder and urethra.

12. Types of UTI
Also can be divided to:
• Primary UTI:
Occur in person with normal urinary
system and mainly in females.
• Secondary UTI:
Due to abnormality or instrumentation
(catheters, tubes and surgery) in both
male and female.

13. Routes of infection
• Ascending (organisms of GIT).
• Haematogenous (Septicemia and
Bacteriaemia such as S. aureus and M.
Tuberculosis).

14. Commensals
Urinary system is sterile (No commensals)
mainly kidneys, ureters and bladder but
some organism can be found in urethra in
small number and they are transient. This
organisms mainly found in females due to:
• Anatomical structure (short urethra)
• hormonal changes,
• wet renal system.

15. Commensals
• All coagulase -ve staph except S.
saprophyticus.
• Viridians and other Haemolytic strept.
• Lactobacilli.
• Diphtheroides.
• Anaerobic cocci.

16. Commensals
• Mycobacterium species (Rapid growers 5-7
days).
• Mycoplasma & Chlamydia.
• Enterobacteriacae (Transient).
• Yeast's (small numbers).

17. Etiological agent
Enteric Gram-Negative Rods
Escherichia coli—the most common cause of
cystitis
Klebsiella spp.—associated with hospital-
acquired UTI
Proteus mirabilis—associated with UTI and
stone formation
Pseudomonas aeruginosa—associated with
hospital-acquired UTI
Other gram-negative

18. Etiological agent
• Gram-Positive Cocci
• Enterococcus spp.—more often associated
with institutionalized patients (hospital,
nursing home) rather than being
community acquired
• Staphylococcus saprophyticus—common
agent of cystitis in young, sexually active
females
• Streptococcus agalactiae (group B strep)—
may cause infection in pregnant women

19. Etiological agent
• Viruses
• Adenovirus—causes hemorrhagic cystitis
in children
• Fungi
Candida spp.—causes UTI in diabetics,
immunocompromised patients, and those
with an indwelling catheter

21. Pathogenesis of urinary tract
infections
• Host factors
• Shorter urethra more infections in females
• Obstruction Enlarged prostate, pregnancy,
stones, tumours
• Neurological problems Incomplete
emptying, residual urine
• catheters and instrumentation of the
urinary tract are major factors
contributing to UTI.

22. Bacterial factors
Fecal flora Potential urinary pathogens
colonize periurethral area
Adhesion Fimbriae and adhesins allow
attachment to urethra and bladder
epithelium
K antigens Allow to resist host defences by
producing polysaccharide capsule
Haemolysins
Damage membranes and cause renal damage
Urease Produced by some bacteria, e.g.
Proteus

23. • Strains of E. coli that cause UTI carry
large blocks of genes within their DNA
called pathogenicity islands (PIs) that are
not found within the genomes of non
uropathogenic strains of E. coli.
• Genes that code for virulence factors such
as fimbriae, hemolysins, capsule
synthesis, iron uptake, and toxins.

24. About 50% of women who present with the
clinical features of cystitis do not have
positive urine cultures, a condition known as
abacterial cystitis or 'urethral syndrome'.
Explanations include:
infection with low counts of bacteria
infection with fastidious organisms not
detected on routine culture.
sexually transmitted infections, e.g.
chlamydia
non-infective inflammation, e.g. chemical.

25. Clinical features and complication
•Acute lower U.T.Is:
–Inflammation of the bladder (Cystitis) is the most
common.
–May associated with Pyuria, hematouria and
bacteriuria.
–Dysuria.
–Urgency.
–Frequency of micturation.
–Asymmptomatic in elderly patient and
catheterization.
•Upper U.T.Is:
–Pyelonephritis associated with fever and lower urinary
tract symptoms.
–Hematuria is a feature of endocarditis, kidney
damage or immune complex diseases.
–Pyelitis is an infection of the ureters associated with
anuria may be due to renal stones.

26. Symptoms
• Dysuria (pain & difficulty in passing urine).
• Urinary frequency & urgency.
• Fever (sometimes) indicates to upper UTI.
• A symptomatic (immunosuppressed
patients, Diabetic and pregnant).

27. Clinical remarks associated with
UTI
• Polyuria (increase in urine output).
• Oliguria (decrease or insufficient production
of urine).
• Pyuria (pus cells in urine).
• Bacteriuria: presence of bacteria in urine.
• Haematuria: presence of blood in urine (in
acute glomerulonephritis complication of
streptococcal infection and in Schistosoma)

28. Clinical remarks associated with
UTI
• Loin pain: pain of the back.
• Burning micturation.
• Renal calculus.
• Renal colic.
• Retentions
• Renal failure (kidney can't produce urine).

29. Laboratory diagnosis
• Specimens:
– Early morning mid stream urine sample collected in a
clean, dry, wide mouth and sterile universal or
plastic container.
– Catheter sample collected by using sterile syringe
during voiding of urine after disinfect the site of the
catheter.
– Suprapubic aspirate directly from the bladder when
there is dysuria.
– Ureteric catheter (Most used to distinguish upper
from lower U.T.I.
– Using sterile Adhesive plastic bag {for collection of
urine in children}.

30. Transportation
• Delaying of the sample more than 30 min
gives false positive results of significant
bacteriuria.
• 1.8 % boric acid stop the multiplication of
bacteria without killing them.
• Refrigeration do the same thing.

31. Sampling from catheter

32. Suprapubic aspirate

33. Macroscopic appearance of sample
Cloudy (with unpleasant smell and
pus cells)
Bacterial infection
Candida infection
Red & cloudy ( Containing red
cells)
Bacterial infection,
Schistosomiasis or
Trichomonas
brown & cloudy (Containing HB.) Black water fever ,other
conditions that cause
intravascular heamolysis
Yellow brown, or green
brown(containing Biluribine)
Acute viral hepatitis or
obstructive jaundice
Yello orange ( containing urobilin
I.e oxidised urobilinogen)
Heamolysis hepatocellular
jaundice

34. Quantitative urine culture
• U.T.I indicated when the bacterial count of one
species exceeding 105 CFU/ml.
• Contaminated sample contain less than 105
CFU/ml with more than one species present.
• By using Standard loop with a diameter allowing
to take 0.001 or 0.01 ml of urine.
• Filter paper method.
• Dip slide methods:
– Slides with 2 different culture medium on their 2 sides.
• Presence of any number of bacteria from
suprapubic aspirate or ureteric catheter must
considered as significant.

36. Culture
• Media of choice is CLED.
– Support the growth of most of the causative agent.
– Stop the swarming of proteus.
– Ability to differentiate between the organisms.
• Alternatively we use Blood agar and
MacConkey.
• Note:
– Single plate for single sample.
– Proper technique of culturing to assess distribution
of the sample and helps in quantitation.

37. Urine deposit
• Presence of pus cells, bacteria and/or nitrate
reduction is an indicative to bacterial U.T.I.
• Pyuria without bacteriuria (Sterile pyuria):
– Appears when there is an infection with organisms
need special condition for their growth e.g.:
Gonorrhoea.
– Urinary tuberculosis.
– Patient under treatment with antimicrobial agents.
– Other disease like neoplasm or urinary calculi.
• Bacteriuria without Pyuria occurs in:
– Early infection
– Upper U.T.I.
– Salmonella infection.
– Leukopenic patient.
– Delay in cultivation without preservation.
– Diabetes mellitus and Endocarditis.

38. Interpretation of the results
• Significant growth:
– Presence of more than 105 CFU/ml
(appearance of more than 100 colonies if we
use 0.001 ml STD loop or more than 1000
colonies when use 0.01 ml loop).
• Insignificant growth:
– Presence of less than 105 CFU/ml.
– May be due to contamination or patient under
treatment.
• No Growth:
– Absence of colonies.

39. Isolation and identification of
the species
• Using colonial morphology.
• Gram’s stain.
• Biochemical tests.

41. Antimicrobial susceptibility test
• Very important to guide teatment.
• Use the standard methods for doing
susceptibility test and report the result as
high sensitive, moderate sensitive and
resistant.
• Use the antimicrobials that could reach the
urinary system in large amount.
• Ciprofloxacin, Norfloxacin, ofloxacin,
Nitrofurantoin, Nalidixic acid,
Cotrimoxazole, Ampicillin, Augmentin,
Cephalosporin.

43. Antibiotic Prophylaxis
• Amoxil 20 mg/kg per day; if given at
bedtime takes advantage of normal
nocturnal urinary concentration overnight
and in toilet trained kids, retention of
antibiotic in the bladder overnight
• Bactrim
• Macrodantin

44. QUESTIONS?