Lower Urinary tract infection-1

Lower Urinary tract infection:
Cystitis, Urethritis, and Prostatitis in men.
Cystitis: is the inflammation of urinary bladder (the sac that
temporarily holds urine until urination) caused by
microbial colonization and infection.
Hemorrhagic cystitis :
is characterized by large quantities of visible blood in the urine. It
can be caused by an infection (bacterial or adenovirus).
Urethritis : It is the inflammation of urethra ( the tube that carries
urine from the bladder during urination) caused by microbial
Symptoms include a burning sensation during urination and fever.
Most of the cases of urethritis without cystitis are sexually
Chronic bacterial prostatitis:
The prostate is a small gland and part of the male reproductive system. It
produces fluid that becomes part of a man's semen, the liquid that helps
transport sperm.
If the prostate becomes inflamed, the condition is called prostatitis.
Etiology of Cystitis and Urethritis (Non-Sexual origin):
Pathogens may ascending the urethra of fecal origin.
1- Escherichia coli.
2- Staphylococcus saprophyticus.
3- Other genera of Enterobacteriaceae :
Klebsiella, Enterobacter, Proteus, and Serratia.
4- Pseudomonas aeruginosa
( Hospital-acquired infection due to contaminated catheter).
5- Enterococcus faecalis .
( Hospital-acquired infection due to contaminated catheter).
Laboratory diagnosis of UTI:
Collection of Clinical Specimens:
Urine specimens:
A- Midstream catch urine: One to Ten ml:
must be collected in sterile urine container , the first portion must be
discarded to avoid contamination with urethra and vaginal bacteria.
B- Catheterized Urine: One to Ten ml
Must be collected in sterile urine container.
C- Suprapubic Urine: One to Ten mL
Aspirated from urinary bladder by fine needle collected in sterile
anaerobic tube.
( young babies, children, obstruction cases).
Cultivation of urine specimens:
Urine specimens should be cultivated on Enriched media (blood
agar) and differential media (MacConkey’s agar or CLED) by the
following methods:
1- Four quadrant streaking method: depends on Calibrated Loop.
:( Semi-quantitative).
2- Network Streaking method: depends on Calibrated Loop.
: ( quantitative).
3- Microbroth dilution method. ( quantitative)
Calibrated loop carry only one microliter.
Isolation of microbe from urine and calculation of CFU :
Bacterial loop carry one microlitre.
When 50 colonies are isolated = 50 cells per/1 µl = 50 CFU/ µl
In one mL : 50 * 1000= 50000 CFU/mL.
CFU cutoff value and significant bacteriuria:
The CFU cutoff value is associated with type of urine specimens.
It is calculated to be equal to:
For Midstream catch urine: 50000- 100000 CFU/m L.
For Catheterized Urine:
100 CFU/m L.
For Suprapubic Urine:
Any growth.
Significant bacteriuria:
Is the isolation of microbes of infectious dose cutoff value from urine
Specimen in presence of signs and symptoms of UTI.
It is mainly associated with pyuria and dysuria.
Isolation of Enterobacteriaceae from urine specimens:
The most important genera that could be isolated from urine are:
Escherichia coli , Klebsiella, Enterobacter, Proteus mirabilis, and
Serratia species.
Enterobacteriaceae genera are classified according to lactose
fermentation into two groups:
1- Lactose none fermenters.
2- Lactose fermenters.
Identification of E. coli:
-Some strains of uropathogenic E. coli are verotoxin producers.
-All strains are oxidase negative and catalase positive.
-Metallic green sheen on EMB agar.
-Uropathogenic E. coli species are indole positive.
Differentiation of Lactose fermenter genera by IMVC test:
The Rapid biochemical identification system: The API20E:
Identification of Proteus species:
All species are Gram’s negative bacilli that illustrate swarming
growth on blood agar.
All are H2S and urease positive.
Isolation of Pseudomonas species from urine specimens:
Cultural characteristics:
-All species of Pseudomonas produce Water soluble Exopigment on
nutrient agar. (greenish yellowish pyoverdin) .
-All species are oxidase positive.
Isolation of Serratia marcescens from urine:
Microorganisms that produce pigment during growth are said to be
Serratia marcescens produces a deep red pigment ( water-insoluble)
at 25°C, but does not produce pigment at 37°C.
Serratia marcescens
Isolation of Gram’s positive Cocci :
-The most important Gram’s positive Cocci that associated with UTI
1-Staphylococcus saprophyticus.
2-Enterococcus faecalis.
-Staphylococcus aureus is also considered as a causative agent of UTI.
Differentiation of Staphylococcus aureus and other Staphylococcus
-All Staphylococcus species are Gram’s positive Cocci arranged in
-All species are Catalase positive.
-Staphylococcus aureus are coagulase positive.
-Staphylococcus epidermidis and Staphylococcus saprophyticus are
coagulase negative.
Staph. aureus
coagulase positive
Other Staph.
Coagulase negative.
-Staphylococcus saprophyticus species are Mannitol fermenters and
Novobiocin resistant.
Novobiocin sensitive Staph.
Mannitol fermentation pattern.
Isolation of Enterococcus faecalis from urine specimens:
Urine specimens should be cultivated on bile esculine salt agar
when Nosocomial UTI is suspected.
Black discoloration of media is a distinctive characteristics of group
D streptococcus growth ( Enterococcus faecalis).
Parasitic infection of urinary system:
Classification (phylum): Trematoda.
Classification according to morphology:
Flattened non-segmented unisexual flukes.
Schistosoma hematobium:
• Found in Middle East, Africa, Portugal and Cyprus
• Definitive host: man
• Intermediate host: snail
• It causes urinary bilharziasis (female deposits eggs in the
vesical and pelvic plexus of venous circulation).
10-20 x I mm with short anterior cylindrical pan and posterior
flattened part which incurved ventrally to form the gynaeccphoric
It has well developed oral and ventral suckers.
15-25 x 0.25 mm:, cylindrical, ovary may
"be central, anterior or posterior, uterus
may be short or long containing eggs.
Schistosoma hematobium ova:
-140x50 µ, oval with terminal spine.
-Passes in urine.
Life cycle:
The clinical picture is divided into three stage:
1-Incubation period; (acute Schistosomiasis 6-12 Weeks) :
This stage is characterized by skin irritation after coming from
water, and coughing.
Late in the incubation period, patients complains of
enlarged liver, fever, headache, anorexia, loss of weigh.
CBC shows Eosinophilia.
2- Stage of egg deposition: (1- 5 years after infection).
Urinary bilharziasis:
caused by S.hematobium, characterized by terminal haematuria,
burning sensation during urination.
3-Stage of complication:
-Due to a fibrosis around the eggs in bladder, liver and
- Obstruction of bladder.
Urinary bilharziasis:
cystitis, hydronephrosis and
Pyonephrosis ,
sterility in males, renal failure,
urinary bladder carcinoma,
pulmonary hypertension and
heart failure.

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