|
ATLAS OF URINE SEDIMENT - Microorganisms |
|
|
|
Written by Administrator
|
|
Tuesday, 07 March 2006 |
CD Chapter Outline:
|
Has the urine been properly sampled and treated, the presence of microorganisms is clinically significant.
Bacteria, fungi, parasites and virus-infected cells are commonly found in the urine. The microorganisms found in the urine should be identified and characterized as extracellular or intracellular structures. Extracellular bacteria, fungi and parasites are easily detected under light microscope. Detection of intracellular phagocytic bacteria and fungi, toxoplasms and inclusions requires cytologic examination of the urine. Stained preparations are very important for accurate identification of microorganisms. Microbiologic cultures are used as a confirmatory test. |
|
 Bacteria
The urine of healthy individuals is sterile and contains no bacteria. A low number of bacteria can be found, though, if the urine has been contaminated due to inappropriate sampling or too long storage of the urine sample. Identification of the bacteria, i.e. spherical (cocci) or rod-shaped (bacilli) bacteria, can be performed by use of the light microscope and phase-contrast microscope. Bacteria usually derive from lower urogenital tract, possibly from an intestinal fistula. Spherical or rod-like bacteria are mostly found in agglomerates or strings. Staining with methylene blue or according to Gram is recommended to differentiate particular species of bacteria.
The presence of bacteria in urinary sediment can be due to inappropriate urine sampling or too long storage at room temperature or urinary tract infection. Concurrent leukocyturia points to the existence of an infection. Definite evaluation of bacterial pathogenicity can only be made on the basis of urinary culture. |
 |
Fungi and spores
Urinary tract fungal infections are usually observed in patients with diabetes, women taking oral contraceptives, and patients on intensive antibiotic or immunosuppressive therapy. Fungi are round or oval in shape, and of a homogeneous texture without inclusions. They are readily recognized by their most pronounced feature of budding. Fungi appear as tangles of threads or twigs.
Spores are small, oval and strongly refracting. The presence of fungi in the urine is indicative of a pathologic process.
Fungi occur in the urine of diabetic patients, pregnant women, and immunocompromised patients (AIDS, immunosuppressive therapy). Fungi may also be a sign of inappropriate preanalytical sample handling (too long storage at room temperature). Fungi are not clinically significant, with the exception of Candida albicans, which can cause vaginitis, urethritis and cystitis. |
 |
|
|
|
Home 
