Pyuria and Bacteriuria: Collection and Transport of Urine

Pyuria refers to the presence of pus cells in urine. The presence of bacteria in urine is called bacteriuria. Significant bacteriuria is usually accompanied by pyuria.

Urine container

COMMON PATHOGENS FOUND IN PYURIA AND BACTERIURIA:

BACTERIA	GRAM POSITIVE: Staphylococcus saprophyticus, haemolytic streptococci, enterococci.
	GRAM NEGATIVE: Escherichia coli, Proteus species, Pseudomonas aeruginosa, Klebsiella species, Salmonella typhi, Salmonella paratyphi, Neisseriae gonorrhoea.
OTHER BACTERIA	Mycobacterium tuberculosis, Leptospira interrogans, Chlamydiae, Mycoplasma
FUNGI	Candida species
PARASITES	Schistosoma haematobium, Trichomonas vaginalis and occasionally Enterobius vermicularis, Wuchereria bancrofti and Onchocerca volvulus



NOTES ON PATHOGENS OF PYURIA AND BACTERIURIA

• Bacteriuria without pyuria may occur in early UTI, diabetes, enteric fever, bacterial endocarditis.

• Pyuria with sterile urine culture may be found with renal tuberculosis, gonococcal urethritis, leptospirosis or when patient treated with antimicrobials.

• E. coli is the commonest cause of urinary infection. Women are more frequently infected than men.

• Pseudomonas, Proteus, Klebsiella infections often follows catheterization and gynaecological surgery.

• Urethritis (Infection of the anterior urinary tract) is mainly caused by N. gonorrhea, staphylococci, streptococci & Chlamydiae.

• M. tuberculosis is usually carried in the blood to the kidney from another site of infection.

• S. typhi & S. paratyphi can be found in the urine of about 25% of patients with enteric fever from the third week of infection.

• Excretion of bacteria is not associated with pyuria. Typhoid carriers may excrete S. typhi in their urine for many years. Carriers are more common in schistosomiasis endemic areas.

• In Leptospirasis, L. interrogans can be found in the urine from about second week of infection.

COLLECTION AND TRANSPORT OF URINE:

In a hospital with a microbiology laboratory:

• Midstream urine is collected for microbiological examination.

• Give the patient a sterile, dry, wide-necked, leak-proof container and explain the importance of collecting a specimen with as little contamination as possible.

• About 20 ml. of urine should be collected.

• Label the container with the date, the name and number of patient and the time of collection.

• Deliver the specimen to the laboratory as early as possible.

In a health centre for dispatch to a microbiology laboratory:

• If immediate delivery to the laboratory is not possible, the urine should be refrigerated at 4° C.

• If a delay in delivery of more than l hour is anticipated boric acid should be added to the urine (0. l gm/10 ml. of urine).

• The following changes occur when un-preserved urine is left at room temperature

• Any bacteria in the urine will multiply so that the bacterial count will be unreliable.

• If the organisms are urease-producing, the ammonia released will increase the pH of the urine which will result in the destruction of cells and casts.

• Bacteria will also breakdown any glucose present in the urine.

• Concentration of protein in the urine will be altered.

• If bilirubin is present this may be oxidized to biliverdin which will not be detected.

• Likewise, urobilinogen will not be detected because it will be oxidized to urobilin.

• If renal tuberculosis is suspected then —> Collect the first urine passed (entire specimen) on three successive mornings.

• The specimens should be stored 4° C. until all three urines have been collected.

Dipslides

• Commercially prepared Dipslides consist of media-coated disposable plastic slide-spoons.

• Inoculation is by immersing the slide-spoon in a container of urine or by allowing a flow of urine to pass over the medium.

• They are used to avoid the overgrowth of commensals when there is likely to be a delay in a specimen reaching the laboratory.

• Dipslides are however expensive, have a shelf-life of only about 4 months from manufacture, and in case of heavy growth, it might be difficult to isolate the pathogen for sensitivity testing.

• Preserving urine using boric acid is less expensive and also enables urine to be examined microscopically.