A urine test helps healthcare professionals identify potential issues within the urinary system by examining the sample for microorganisms. Sometimes, a report may indicate “mixed urogenital flora,” which refers to the detection of several different types of bacteria within the urine sample. Understanding this term can clarify your results.
Understanding Urogenital Flora
The human body naturally hosts a vast community of microorganisms, collectively known as microbiota or flora, on its surfaces and within certain cavities. These microscopic organisms, primarily bacteria, play significant roles in maintaining health. The urogenital tract, encompassing the urinary and reproductive organs, is no exception to this microbial colonization, with different regions having their own characteristic microbial populations.
The skin surrounding the urethra is home to a diverse array of bacteria. This external area, along with the very end of the urethra, naturally harbors various bacteria such as Staphylococcus species (e.g., S. epidermidis), Corynebacterium species, and various Lactobacillus species, particularly in females. These organisms are part of the normal skin and mucosal flora and typically do not cause infection in healthy individuals.
In contrast to external regions, healthy urine within the bladder is generally considered sterile. The urinary tract above the urethra, including the bladder, ureters, and kidneys, is designed to be a sterile environment. Any significant presence of bacteria in urine collected directly from the bladder typically indicates an infection. However, when a urine sample is collected, it must pass through the urethra and past the surrounding skin, making it susceptible to picking up naturally occurring external microbes.
What “Mixed Urogenital Flora in Urine” Means
When a laboratory report identifies “mixed urogenital flora” in a urine sample, it indicates that multiple different types of bacteria have been found. This finding often leads to two primary interpretations, with the most common being sample contamination. The distinction between these interpretations is important for proper diagnosis and subsequent management.
Sample contamination occurs when bacteria from the skin, external genitalia, or vaginal area inadvertently enter the urine sample during collection. For instance, bacteria from the perineal skin, such as Staphylococcus epidermidis or Corynebacterium species, can be washed into the urine stream. In females, vaginal bacteria, including various Lactobacillus species or Gardnerella vaginalis, may also contaminate the sample. Similarly, in males, skin flora from the penis can introduce bacteria. This type of contamination is usually benign and does not indicate an infection requiring treatment.
This contamination often happens if the “clean catch” urine collection technique is not followed precisely. The clean catch method involves cleaning the genital area, beginning to urinate into the toilet, and then collecting the middle portion of the urine stream in a sterile cup. This technique aims to flush away external bacteria and collect urine directly from the bladder, minimizing contamination. Despite best efforts, some external bacteria can still enter the sample, especially if cleaning is insufficient or the urine stream touches the surrounding skin.
While contamination is the most frequent explanation, “mixed urogenital flora” can occasionally signify a true polymicrobial infection. A polymicrobial infection involves multiple types of bacteria causing an infection simultaneously. Although less common than infections caused by a single bacterium, such as Escherichia coli in typical urinary tract infections (UTIs), polymicrobial UTIs can occur. These are sometimes seen in individuals with complex medical conditions, urinary catheters, or structural abnormalities of the urinary tract. For example, long-term indwelling catheters often lead to biofilms containing multiple bacterial species.
Distinguishing between contamination and a true polymicrobial infection is crucial for appropriate medical action. Treating contamination with antibiotics is unnecessary and can contribute to antibiotic resistance, while an untreated polymicrobial infection could lead to more severe health complications. Healthcare providers therefore carefully consider other factors beyond the laboratory report to make an accurate diagnosis. The presence of symptoms and the quantity of different bacterial types detected play a significant role.
Interpreting the Findings and Next Steps
Upon receiving a urine test result indicating “mixed urogenital flora,” a medical professional considers several factors beyond the laboratory report to interpret the findings accurately. One important consideration involves the patient’s symptoms. If a patient reports classic signs of a urinary tract infection, such as painful urination (dysuria), increased frequency or urgency, lower abdominal pain, or fever, the mixed flora result might suggest a true infection. Conversely, if the patient has no symptoms, the mixed flora is much more likely due to contamination.
The urine sample collection method also provides valuable context. A sample collected without proper “clean catch” technique, or one from an infant’s collection bag, is more prone to contamination from external skin and genital flora. Healthcare providers inquire about the collection process to assess the likelihood of external bacteria introduction. This information helps decide if the result reflects the bladder’s contents or is merely a collection artifact.
Another factor is the bacterial count, referring to the number of bacterial colonies per milliliter of urine. Low bacterial counts, often below 10,000 colony-forming units per milliliter (CFU/mL), particularly with multiple different types of bacteria, frequently suggest contamination. Higher counts, typically above 100,000 CFU/mL, especially if one or two specific bacterial types predominate, are more indicative of a true infection. The specific bacteria identified are also important; some, like E. coli, are common UTI pathogens, while others, like certain Staphylococcus species, are more often contaminants when found in low numbers.
Based on the overall clinical picture, several next steps might be recommended. If the patient is asymptomatic and mixed flora is suspected contamination, repeating the urine test with strict adherence to the clean catch method helps obtain a more reliable sample. If an infection is still suspected despite mixed flora or persistent symptoms, further diagnostic tests might be ordered, such as a urine culture with sensitivity testing or imaging studies. Treatment with antibiotics is typically prescribed only when a true infection is diagnosed, based on symptoms, bacterial counts, and the type of bacteria identified, rather than solely on mixed flora.