At the end of this chapter the students will be able to: List the types of biochemical tests Describe the principles of biochemical tests List the required materials for the biochemical tests Describe the procedures of biochemical tests Identify test result and positive and negative control bacteria for the specific biochemical tests Discuss the principle, material required, procedures and interpretation of API-20E test strips used to identify the enteric gram negative rods

1. ASSGINMENT OF
URINANLAYSIS
Name ferhan kadir
ID number 0153/03

2. Urine leukocyte esterase
Urinary Leukocyte Esterase (or Leukocyte Esterase, for short) is an enzymatic marker that is
commonly used to detect the presence of white blood cells (leukocytes) in the urine. It is a
simple and quick test that can be done by using a dipstick to check for the presence of this
enzyme in the urine.
When white blood cells are present in the urine, it can be an indication of a urinary tract
infection (UTI) or some other type of inflammation in the urinary tract. The leukocyte esterase
test works by detecting the presence of these white blood cells and can help diagnose a UTI or
other urinary tract disease.

3. Cont..
•Leukocyte esterase is present only in neutrophils.
•Few neutrophils can be seen in normal urine.
•Increased numbers of neutrophils usually indicate the
presence of a urinary tract infection.

4. Cont..
• Neutrophils contain enzymes known as esterases. These esterases can
be detected by reagent strips that contain an appropriate substrate
such as indoxylcarbonic acid ester and is based on the reaction
shown. The reagents used for this reaction vary by manufacturer.
• Leukocyte esterase results are read at 2 minutes. A positive reaction
produces a lavender to purple color with a reporting range of values
from trace to large. Values reflecting cell numbers from negative to
500 may be reported.

5. Leukocyte Esterase Purpose
 Increased WBC in urine is pathologic
 Indicates inflammation, infection
 Neutrophils most common type of WBC found in
urine
 Can detect intact WBC and lysed WBC

6. Urine leukocyte esterase: false positive
•Strong oxidizing agents
•Contamination by vaginal discharge
•Formalin used as preservative
•Drugs containing imipenem, meropenem, or clavulanic acid
•Nitrofurantoin contributes a color to urine that may cause
misinterpretation

7. Cont…
• Strong oxidizing agents cause a false-positive leukocyte esterase result. This
occurs when strong detergents used to clean the collection container remain
present.
• False-positive results may also be obtained on females due to contamination
• of the urine with vaginal discharge.
• Some preservatives such as formalin will cause a false-positive result.
• False-positive results may be caused by drugs that contain imipenem,
meropenem, and clavulanic acid.
• Nitrofurantoin contributes a color to urine that may cause misinterpretation
of this test.

8. Urine leukocyte esterase: false negative
• High specific gravity and in urines containing glucose and protein.
– WBCs creanate and cannot release esterase
• Ascorbic acid
• Oxalic acid
• Cephalexin
• Cephalothin
• Gentamicin
• Tetracycline

9. Cont…
• False-negative results may occur with high specific gravity and in urines
containing glucose and protein. Significantly high levels of protein or
glucose can contribute
• to increased specific gravity. In such an environment, white blood cells will
crenate and be unable to release esterase.
• Various drugs and chemicals interfere with this test. Check the packaging
insert of the reagent strip manufacturer for specifics concerning interfering
substances. Some
• drugs and chemicals that may cause false-negative results include ascorbic
acid, oxalic acid, cephalexin, cephalothin, gentamicin, and tetracycline.

10. Leukocyte Esterase Normal
 Normal negative
 Bacterial infection
 cystitis, pyelonephritis, urethritis
 Non-bacterial infection yeast, trichomonas

11. Leukocyte Esterase
 Sensitivity 5-15 WBC/hpf
 False positive vaginal contamination color
masking
 False negative strong oxidizing agents (bleach)
lymphocytes (no granules)

12. Summary
• Urinary Leukocyte Esterase test is a screening test used to detect the
presence of leukocytes in the urine, which can indicate a urinary tract
infection or other urinary tract diseases. However, it is not a definitive
test and further testing may be required to confirm the diagnosis.