Urine Culture and Urinalysis Experiment


This lab report analyses the findings of two important tests. These are microbiological analysis of urine on CLED agar plate (urine culture) and biochemical analysis of urine (urinalysis). Urine culture test examined urine sample cultured on cystine-lactose-electrolyte deficient agar plate for just about any possible bacterial growth after the incubation period. Gram positive or gram negative bacteria growth can be found or not. However the occurrence of 10 colonies of every in this experiment which were E. coli and S. aureus bacteria indicated either possible contamination of the urine sample or infection of the urinary tract by various disease and disorders of the urinal tract.

The biochemical analysis of urine was also done where by the sample urine both negative and positive controls were subjected to tests for occurrence of different constituents not normally found in normal urine using test strip with absorbent pads capable of testing different constituents by observation of color change. Presence of unexpected urine constituents indicates infection of the urinal tract and sometimes certain diseases, disorders and nutrition imbalance.


Urinalysis which is also termed as biochemical analysis of urine is a biochemical test on urine sample purposely meant to assist in diagnosis of a variety of urinary tract diseases. Types of such diseases include high urinary sugar levels in people suffering from diabetes, high ketone bodies levels in urine in situations of ketunia among other urinary disorders. Urine is also at the mercy of immunological analysis and these tests will be the ones used to detect pregnancy (Carricajo, 1999).

Microbiological analysis of urine also termed as urine culture is a microbial test in charge of detection of pathogenic microbes capable of creating urinal tract diseases and disorders (Martinko, 2005). The enumeration of such microbes for our case is by use of cysteine-lactose and electrolyte-deficient agar mostly abbreviated as CLED agar. However other styles of agar media that can be used rather than CLED agar include blood agar and MacConkey agar. CLED agar medium is a non selective medium which can support growth of many pathogens within the urinary system and has the capacity to give a clear differentiation of such pathogen's colonies with minimum or no proteus species spread (Kee, 2001).


For biochemical analysis of urine, both negative and positive control samples of urine were conducted by strict following of the instructions by the manufacturer. A test strip detecting eight different substances was dipped in to the urine sample, then the strip was taken out and the extra urine was removed by wiping the edge of the strip to the inner side of the tube. The colour of the pads on the strip was observed for just about any changes and the pads were read within the direction of the arrow and within enough time given in the container. The reading was recorded and the test was repeated for a negative control urine sample (Clarridge, 1998).

For the urine culture test, the cysteine-lactose and electrolyte-deficient agar medium was prepared based on the instructions provided on the label by the manufacturer by first weighing accurately and dissolving in appropriate amount of distilled water. Sterilization of the media was then conducted at 121 degrees Celsius for 15 minutes in an autoclave (Nunez, 1995). The sterilized media was the poured on to several sterilized plate for solidification and this was done over a sterile and clean microbiology working bench. After acquiring the urine sample for microbial analysis, the sample was mixed gently to avoid foaming and the finish of an sterile 10 micro-liter calibrated loop was dipped in the urine sample to just underneath the surface and was removed vertically. Then the level of urine within the calibrated loop was inoculated over the whole surface of CLED agar plate, which was then incubated in ambient air overnight at 37 degree Celsius (Chernecky, 2001).


For the urine culture test, this examined a urine sample cultured on cystine-lactose- electrolyte deficient agar plate for just about any possible bacterial growth after the incubation period of 24-48hours. Urine culture was positive with two bacterial species growth observed in line with the typical colonial morphology and colors on the CLED agar plate. A count of 10 colonies of Gram negative bacteria E. Coli were recorded on the CLED plate as well as 10 colonies of gram positive S. aureus. The amount of colony from each bacterial species isolated on the agar plate was then multiplied by the dilution factor of 1 1. 000. 000 to secure a density of 10. 000. 000 CFU/L of urine.

For urinalysis, a test that allows us detect abnormal constituents of urine such as glucose, protein, ketones bodies, blood and bile pigment, the positive control urine test outcomes showed abnormalities in its constituents by the existence leukocytes, blood, nitrites, proteins and ketones bodies in the sample set alongside the negative control urine which showed normal results in its constituents.

Discussion of the results

Urine is a by product and it is stated in the kidneys and then in to the urinary bladder where it accumulates till enough stretching of the bladder walls is achieved which contributes to its release via the urethra. Urinalysis is vital to determine whether the urine is normal or if it's from unhealthy individual since it includes different ranges of waste products which should be present in normal urine yet others that are not expected in normal urine thus there presence indicates certain diseases and disorders. Urinalysis gives us a indication of the internal biochemical processes of the individual under test. According to this experiment, the presence of leukocytes, blood, nitrites, proteins and ketones bodies in the positive control urine sample indicated the next. Presence of leukocytes indicates shows us that the urinary tract that the urine was obtained was infected and this is evident due to detection of esterase enzyme which is generally absent is normal urine. This indicates that this sample of urine should go through further tests like culture test, sensitivity and even microscopy (Kouri, T. (2000).

Healthy individuals do not contain ketone bodies in their urine. Therefore occurrence of ketone bodies in the urine sample tested indicates that the individual was deprived of carbohydrates since ketones and acetones are in reality the byproducts of metabolism of the fat. This demonstrates the individuals was either suffering from diabetes mellitus or he individual was lacking carbohydrates since both of them are possible factors behind existence of ketones and acetones in the urine. When urine is detected to get blood, it indicates an ailment known as hematuria. Sometimes the blood may not be visible to your naked eyes and this is called microscopic hematuria while sometimes the blood stains are noticeable to your eyes and this is known as frank hematuria. Many renal conditions exhibit this problem of henaturia. "Included in these are renal, urethral and ureteric calculi, acute nephritis, malignant papiloma, renal ca, and chronic kidney diseases and sometimes the administration of sulfonamides or anticoagulants may cause hematuria" (Wallach, 2000, p. 26). The salt of nitrous acid is recognized as nitrate. So when the urine tests positive of nitrates, it indicates firmly that the urinary tract is infected and perhaps by bacteriuria which can be an indication of pyelonephritis, cystitis and sometimes urethritis disorders. But sine the next sample of urine did not show some of this constituents, it indicates that the urine came from a wholesome individuals. However other dangerous constituents which should not be found in normal urine include urobinogen, glucose, Bilirubin, urobilinogen amongst others (Henry, 20005).

In the truth of urine culture test, E. coli is a bacteria that is often within the gut which is harmless unless it if finds its way to wrong venue of the body like the bladder. Therefore existence of these bacteria which really is a gram positive bacterium detected by pinkish color on the plates and S. aureus which is a gram negative bacteria indicated by bluish or purple coloration on the plate indicated that the person that the urine was obtained from might be suffering from urinal tract infections mostly the bladder infections. It could also indicate contamination of the urine sample as the results obtained suggests a probable contamination as two bacterial species were isolated and there was no predominance between your two of them (Aspevall, 2000).


In conclusion, these test outcomes were expected and significant in both urine culture and urinalysis. Urine culture on CLED agar plate was very useful for the growth and enumeration of gram positive and gram negative urinary tract microorganisms while urinalysis was equally needed for providing critical information to aid in diagnosis, monitoring and treatment of wide selection of diseases.

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