Patient 5

Patient 5
Name: Wong Wei Hong
Sex: Male
Age: 67 years
Complaints: Fever, chills, bladder distension; on indwelling catheter
Diagnosis: Urinary Tract Infection
Antibiotic treatment: Nil
Specimen: Urine

Definition
Urinary Tract Infection, or known as UTI, is an infection affecting one or more components of the urinary tract, which consists of two kidneys, two ureters, a bladder and a urethra.

Cause of Infection
A possible way for this patient to be infected with UTI is through the insertion of the indwelling catheter into his bladder. The purpose of inserting the indwelling catheter is to allow the drainage of urine out of the bladder. This would indicate to us that the patient might be suffering from a kidney disorder, as he cannot empty his bladder.

However, the use of a catheter may physically disturb the protective lining of the bladder wall, thus allowing bacteria to invade the exposed epithelium In addition to this, when the catheter is not thoroughly sterile, this could cause microorganisms to be present on the surface of the catheter upon insertion into the bladder. This would allow the bacteria to proliferate inside the bladder and thus resulting in the patient to develop a UTI infection.

Investigation Required
Urinalysis
It involves a physical and chemical examination of urine. In addition, the urine is spun in a centrifuge to allow sediments containing blood cells, bacteria, and other particles to collect. This sediment is then examined under a microscope. A urinalysis offers a number of valuable clues for an accurate diagnosis by,

• Observing the colour of the urine and presence of cloudiness (if any)
• Measuring the acidity of the urine
• Counting the number of leukocytes, which is indicative of UTI



Urine Culture
The procedure to detect for any bacterial growth in the urine is called a urine culture. This method involves the inoculation of the urine specimen onto agar mediums. The mediums required are Blood Agar, MacConkey Agar and Cysteine Lactose Electrolyte Deficient (CLED) Agar. The inoculated specimen is then streaked on the respective plates.

Blood Agar contains general nutrients and 5% sheep blood and it is useful for cultivating fastidious organisms and for determining the hemolytic capabilities of an organism.

MacConkey Agar is a differential medium used to isolate and distinguish lactose-fermenting organisms from non-fermenting Gram-negative enteric bacteria.

CLED Agar is a selective medium and inhibits swarming of Proteus species. In addition to this, they promote the growth of Candida and prevent the growth of pseudomonal.

All the 3 agar mediums will then be placed in an O2 incubator and left overnight before they are read the following day. If the Blood Agar shows a ‘swarming’ effect, this would probably indicate that the microorganism is Proteus mirabilis.

Gram Staining
After a urine culture has been performed, a Gram stain would be done using the isolated colonies from any of the agar mediums. This would help to identify if the microorganism is a Gram-positive cocci (GPC) or a Gram-Negative bacilli (GNB). Under microscopy, a GPC would appear bluish or purplish in colour and the cells would be circular. On the other hand, a GNB would turn out reddish or pinkish in colour while the cells would appear rod-shaped.

Biochemical Tests
After Gram staining has been, a few biochemical tests would be done to determine the suspected microorganism. A GNB would normally be an Escherichia Coli (E. coli) and to prove this, an oxidase test is done. E. coli would turn out to be oxidase negative. A GPC would most likely turn out to be a staphylococcus species, and a microorganism under this species would be Staphylococcus aureus. And to determine if the microorganism is likely to be Staphylococcus aureus, a latex test is done. This micro organism would be latex positive.

Antibiotic Susceptibility Test
After the microorganism has been classified, an antibiotic susceptibility test would be carried out to determine the antibiotics that the microorganism is sensitive to. This would allow the physician to prescribe the necessary antibiotics to the patient. In the event that the microorganism is resistant to majority of the antibiotics, stronger types of antibiotics would be given.

Suspected Organisms
Some of the suspected organisms that could lead to a UTI infection are listed as follows.

1) Escherichia coli
2) Proteus mirabilis
3) Pseudomonas aeruginosa
4) Staphylococcus aureus



References

http://www.reutershealth.com/
http://calder.med.miami.edu/
http://dentistry.ouhsc.edu/
http://en.wikipedia.org


Posted by Farhan