The urine culture is used to diagnose a urinary tract infection (UTI) and to identify the bacteria or yeast causing the infection. It may be done in conjunction with susceptibility testing to determine which antibiotics will inhibit the growth of the microbe causing the infection
Results of a urine culture are often interpreted in conjunction with the results of a urinalysis and with regard to how the sample was collected and whether symptoms are present. Since some urine samples have the potential to be contaminated with bacteria normally found on the skin (normal flora), care must be taken with interpreting some culture results.
Typically, the presence of a single type of bacteria growing at high colony counts is considered a positive urine culture. For clean catch samples that have been properly collected, cultures with greater than 100,000 colony forming units (CFU)/mL of one type of bacteria usually indicate infection. In some cases, however, there may not be a significantly high number of bacteria even though an infection is present. Sometimes lower numbers (1,000 up to 100,000 CFU/mL) may indicate infection, especially if symptoms are present. Likewise, for samples collected using a technique that minimizes contamination, such as a sample collected with a catheter, results of 1,000 to 100,000 CFU/mL may be considered significant.
Although a variety of bacteria can cause UTIs, most are due to Escherichia coli, bacteria that are common in the digestive tract and routinely found in stool. Other bacteria that may cause UTIs include species of Proteus, Klebsiella, Enterococcus, and Staphylococcus. Occasionally, a UTI may be due to a yeast, such as Candida albicans; urethritis is often due to a sexually transmitted disease such as herpes, chlamydia, or gonorrhea.
A culture that is reported as "no growth in 24 or 48 hours" usually indicates that there is no infection. If the symptoms persist, however, a urine culture may be repeated on another sample to look for the presence of bacteria at lower colony counts or other microorganisms that may cause these symptoms. The presence of white blood cells and low numbers of microorganisms in the urine of a symptomatic person is a condition known as acute urethral syndrome.
If a culture shows growth of several different types of bacteria, then it is likely that the growth is due to contamination. This is especially true in voided urine samples if the organisms present include Lactobacillus and/or other common nonpathogenic vaginal bacteria in women. If the symptoms persist, the healthcare practitioner may request a repeat culture on a sample that is more carefully collected. However, if one type of bacteria is present in significantly higher colony counts than the others, for example, 100,000 CFUs/mL versus 1,000 CFUs/mL, then additional testing may be done to identify the predominant bacteria.
If a culture is positive, susceptibility testing may be performed to guide treatment. Any bacterial infection may be serious and can spread to other areas of the body if not treated. Pain is often the first indicator of an infection. Prompt treatment, usually with antibiotics, will help to alleviate the pain.
Minimizing Legionella growth in complex building water systems and devices, including potable water, hot tubs, decorative fountains, and cooling towers, is key to preventing infection. Timely identification and reporting of legionellosis cases is also important because this allows public health officials to quickly identify and stop potential clusters and outbreaks by linking new cases to previously reported ones.
A UTI is most often treated with a round of antibiotics. The type of antibiotic prescribed can vary according to what kind of bacteria you are fighting off, your medical history, and whether or not your UTI has been recurrent. If you continue to have frequent UTIs, you may need to be tested for your susceptibility to them.
You can begin to treat a UTI at home by drinking plenty of water and urinating frequently. Every opportunity you have to try to flush out some of the bacteria will help your body to recover more quickly. Vitamin C supplements will help boost your immune system. Think of them as ammunition for your white blood cells as they fight the infection.
Test Method 1 : A urine sample can also be collected with a urinary collection bag. This method is used most commonly with children and infants. For this procedure, a plastic bag is attached with adhesive to a girl's labia or a boy's penis. When the child begins urinating, the bag catches the urine, which can then be sent to a lab for analysis.