Transcript Urinary Tract Infections (UTI)

Urinary Tract Infections (UTI)
Definition
• UTI is defined as the presence of microorganisms in the urinary tract.
• Most patients with UTI have significant
bacteriuria, i.e. more than 105 CFU/ml, in
a suitably collected mid-stream urine.
Types of UTI
• Urethritis
• Cystitis
• Acute bacterial pyelonephritis
Pyelonephritis
• An infection of the upper urinary tract
(kidney).
• Common clinical symptoms include: fever,
and flank pain accompanied with
bacteriuria and pyuria.
Cystitis
• An infection of the lower urinary tract
(bladder).
• Common clinical symptoms include;
urgency, frequency, and pain on urination,,
and occasionally fever.
Pathogenesis and route of
transmission
Organisms from the faecal flora usually
enter the urinary tract by;
1. Direct or ascending route; via the
urethra to the urinary bladder and the
kidney where they multiply and produce
toxins, the female are more prone to
infection because of short urethra.
2. Blood; from septic focus causing
bacteremia and UTI.
Predisposing factors
• Age; Incidence increase gradually with
age.
• Sex; The short female urethra greatly
predisposes to infection of UT by
ascending route.
• Instrumentation and surgery.
• Other host factors as; D.M and
immunosuppresion by steroids or cytotoxic
drugs.
Commensals
• Urinary tract is normally sterile, except of urethra
which may contain a few commensals such as
acinetobacter species, and diptheriods. Yeast
may also be found in the female urethra.
• Contamination of the urine with skin
commensals including staphylococci,
dipththeroids, and mycobacterium smegmatis
may occur as a specimen is being collected.
• In female patients, the urinary may become
contaminated with organisms from the vagina
(epithelial cells)
Causative organisms
• Gram +ve: Enterococci, Staphylococcus
saprophyticus.
• Gram –ve: Escherichia coli, Proteus
species, Pseudomonas aeruginosa,
Klebsiella strains.
• Also: Mycobacterium tuberculosis
Escherichia coli
• E. coli (serotypes: 02, O4, O6) which are
fimbrinated strains adhering to uroepithelial cells, leading to colonization and
infection is the commonest cause of
urinary tract infections.
Gram negative bacilli
• Pseudomonas, Proteus, and Klebsiella
infections often follow catheterization and
gynecological surgery (nosocomial
pathogen).
• Infection with proteus may be complicated
by phosphate stone formation as it is urea
leads to alkaline pH.
S. saprophyticus
• Infection more common in young women.
Specimen collection
• Samples should be collected before the
start of antibiotics.
• Transport within 2 h. if delay is suspected
then refrigeration at 4C or boric acid.
• Mid stream urine.
• Adhesive bags; in infants.
Macroscopic examination
•
•
Pus, blood and turbidity.
Strip: nitrite for infection/ leukocyte
esterase for pyuria/ pH for proeus.
• Microscopic examination;
1. Epithelial cells.
2. Leuckocyte.