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Urine Isn’t Free of Bacteria


FRIDAY, April 3, 2015 (HealthDay News) — Though it’s commonly believed that urine is bacteria-free, normal urine is not sterile, a new study finds.

“Clinicians previously equated the presence of bacteria in urine to infections. The discovery of bacteria in the urine of healthy females provides an opportunity to advance our understanding of bladder health and disease,” study author Alan Wolfe, a professor in the department of microbiology and immunology at the Loyola University Chicago Stritch School of Medicine, said in a university news release.

Instead of collecting urine samples from a woman’s urine stream, the researchers used catheters to collect urine directly from the bladder.

Testing this way revealed that bacteria were present in urine taken from the bladders of healthy women. The researchers also found that some of those bacteria may contribute to urinary leakage or a loss of bladder control (incontinence).

Additionally, the study found that some types of bacteria are more common in women with urinary incontinence.

“While traditional urine cultures have been the gold standard to identify urine disorders in the past, they do not detect most bacteria and have limited utility as a result. “They are not as comprehensive as the testing techniques used in this study,” Wolfe explained.

“Physicians and researchers must reassess their assumptions surrounding the cause of lower urinary tract disorders and consider new approaches to prevent and treat these debilitating health issues,” Wolfe said.

The study was published recently in the journal European Urology.

“If we can determine that select bacteria cause various lower urinary tract symptoms, we may be able to better identify those women at risk and more effectively treat them,” study co-author Dr. Linda Brubaker, dean and chief diversity officer at the Loyola University Chicago Stritch School of Medicine, said in the news release.

More information

The U.S. Office on Women’s Health has more about urinary incontinence.

Copyright © 2015 HealthDay. All rights reserved.


Bacteria in Urine


The kidneys perform the important function of filtering the blood and this process leads to the formation of the waste product, i.e. urine. The important minerals and nutrients are retained by the kidneys in the blood, and the unwanted, waste materials are filtered out. Such water soluble waste then passes from the kidneys via the narrow pipes called ureters and get collected in the bladder in the form of urine. The urine is then eliminated from the body via a tube known as urethra.

Urine generally tends to have a sterile nature. However, bacteria may occasionally pass onto different areas of the urinary tract. This may result in multiplication of bacteria. When the growth of bacteria is found in a sample of urine, then the affected individual is diagnosed with a condition called bacteriuria. It is generally referred to as urinary tract infection, when more than 100,000 pathogenic bacteria per milliliter of urine, is detected in the sample of urine. It is important that such bacteria belong to a single species.

Bacteria in Urine – Test


Bacteria in Urine – Test

When a urine sample is detected with different types or species of bacteria, then it is possible that the sample is probably contaminated. In such a scenario, a new sample of urine would be needed for a fresh diagnosis to detect the presence of bacteria in urine.

When infected by bacteria in urine, the affected patients usually tend to visit a doctor with complaints of symptoms such as painful urination or the presence of burning sensations during urination. The doctor may then ask for a test of the urine that involves a urinalysis as well as a microbial culture of the sample of urine. The results obtained from the above tests aid in confirmation of bacteria in urine and also provide other necessary information.

Bacteria in urine may cause some symptoms or it may be asymptomatic. An individual who is affected by the presence of an excessive number of bacteria in the urinary tract but does not experience any symptoms is said to be affected by the asymptomatic form of bacteria in urine. This type of bacterial infection in urine is not serious in nature. However, any individual who has undergone a kidney transplant, or is diabetic; or if the said individual is a pregnant women, then that person needs to seek medical attention even for asymptomatic cases of bacteria in urine. Untreated cases of urinary tract infection and bacteria in urine can result in serious health complications.

Symptoms of bacteria in urine

  • Increased pressure during urination
  • Sensations of pain and burning during urination
  • Persistent urge to urinate
  • Putrid smelling urine
  • Bloody urine

Causes of bacteria in urine

Urine does not contain considerable number of microorganisms. In certain cases, bacteria may enter the urinary system and make its presence felt in the form of bacteria in urine and other visible symptoms. The different kinds of bacteria that can infect the urinary system and be detected in a urine sample are Enterococcus faecalis, Chlamydia, Escherichia coli, Lactobacillus and Klebsiella pneumoniae

A few of the above mentioned bacteria are perennially present in the gastrointestinal tract and may pass to the urethra from the bowel. Hence, individuals who do not maintain good personal hygiene are at an increased vulnerability to developing bacteria in urine.

Women are generally more vulnerable to infections of the bladder as compared to men. This is because women have shorter urethral duct. Additionally, the urethral tube is really close to the vagina and also the anus. When women become pregnant there is a change in the way the urinary tract is positioned, which increases the risk to development of bacteria in urine. Hence, it is advisable for pregnant women to regularly visit their physicians and get a urinalysis as well as a urine culture done, so as to check for bacteria in urine.

Any infection of the urinary tract in children may result in the development of a medical condition known as vesicoureteral reflux which causes the urine to flow back to the ureters from the bladder. This may lead to the growth of bacteria in urine

Inflammation or enlargement of the prostate is generally the most likely cause of bladder infections in men, leading to bacteria in urine. Infections of the urinary tract is also possible when there is any blockage of the urine flow as a result of kidney stones, or when there in incomplete elimination of urine from the bladder.

Withholding urine for prolonged periods can also increase the risk to bacterial infections in urine. Additionally, prolonged use of bladder catheters increase the vulnerability to developing bacteria in urine

Treatment of bacteria in urine

  • Asymptomatic cases of bacteria in urine generally do not need any treatment, except for pregnant women and individuals with weakened immune systems. Such people need to consult a doctor for appropriate treatment.
  • Bacterial infections of the kidneys may be treated via antibiotics. Kidney stones and other diseases of the kidney may be treated by the doctor as per the individual cases and surgery may be one of the options
  • Infections of the urinary tract may be treated with different antibiotics.

Bacterial Infections in the Urine

Bacteria in Urine – Test

Bacteria are subjectively quantified in urine as: few, moderate and many. They can be detected in unstained urine sediments when in sufficient quantity.

Identification: Rod-shaped bacteria and chains of cocci are often readily identifiable. The top panel of the image at right show E.coli bacilli from a case of cystitis in a dog. However, small amorphous crystals, cellular debris, and small fat droplets can either mask or mimic cocci (see below for more information). If there is any doubt about the presence of bacteria, a Gram-stained smear of urine sediment (middle panel) should be examined. This gram stain confirms the presence of gram negative bacilli. Note that only extracellular bacteria can be visualized on an unstained urine sediment. Intracellular bacteria can only be identified by cytologic examination of a Wright’s-stained smear of the urine sediment (the bottom panel demonstrates phagocytized bacteria within a neutrophil. The neutrophil’s nucleus is swollen as a storage-related artifact).

Interpretation: Bacteria may be insignificant contaminants or important pathogens. Distinguishing between these possibilities relies on clinical signs, the method of urine collection, the number and types of bacteria, the presence of leukocytes in urine, the length of urine storage, and any underlying disease in the animal.

Since urine in the bladder of normal animals is sterile, bacteria are not normally seen in urine, however this does depend on the method of collection. A few bacteria from the distal urethra and/or genital tract) may be seen in voided urine, however usually numbers are too low if a good mid-stream collection was obtained. Large numbers of bacteria, particularly of a uniform type or accompanied by pyuria (leukocytes), may still be relevant in a fresh voided urine sample (contaminating bacteria will proliferate with storage).
Bacteria are of clinical significance (regardless of numbers) if they are observed in urine collected by cystocentesis (this is a sterile procedure or a clean catheterization.
Bacteriuria of clinical significance, e.g., bacterial cystitis, is usually accompanied by increased numbers of white cells (pyuria). However, some animals with pyelonephritis or underlying immunosuppression (e.g. diabetes mellitus) may have clinically relevant bacteriuria without pyuria.
Cocci in urine

Upper panel: Low magnification view showing increased numbers of leukocytes and several struvite crystals (unstained wet prep). The leukocytes provide clear evidence of an inflammatory process; the background appears “busy”, but bacteria are not reliably identifiable at this magnification.

Middle panel: High magnification view of unstained wet prep showing leukocytes and clumps and chains of bacteria (arrows). Amorphous crystals or debris, however, can have a virtually identical appearance. Use of phase contrast microscopy can help in distinguishing between the two, but examination of a gram-stained drop of the urine sediment is most reliable.

Lower panel: High magnification view of a gram-stained slide. A neutrophil and gram positive cocci arranged in clusters and short chains are shown (arrows: some organisms have partially or completely decolorized). It can be concluded that the inflammatory process is caused or complicated by bacterial infection.