The presence of Lactobacillus species in urine during pregnancy is important for expectant mothers. While these bacteria are generally considered beneficial, their appearance in a urine sample requires understanding, especially given the physiological changes that occur during pregnancy.
Lactobacillus: Beneficial Bacteria
Lactobacillus are a diverse group of rod-shaped, gram-positive bacteria. These bacteria are facultative anaerobes, meaning they can survive in environments with or without oxygen.
In the human body, Lactobacillus species are common inhabitants of the gastrointestinal tract and the female genitourinary tract. They contribute to maintaining a healthy balance of the microbiome by fermenting carbohydrates into lactic acid. This process lowers the pH of their environment, which can inhibit the growth of harmful bacteria.
In the female urogenital system, Lactobacillus strains are frequently present and play a role in defending against harmful pathogens. They produce lactic acid, which acidifies the vagina, creating an environment less favorable for pathogen growth. This defense also involves outcompeting pathogens for resources and attachment sites.
Understanding Lactobacillus in Pregnancy Urine Tests
Urine is generally considered to be free of living microorganisms when it is produced in the kidneys and stored in the bladder. However, it can become non-sterile as it exits the body, picking up bacteria from the urethra and surrounding areas. Recent research indicates that even healthy bladders contain low levels of bacteria, challenging the traditional “sterile urine” view.
When Lactobacillus species are detected in a urine sample during pregnancy, there are two main explanations. The most common is contamination of the sample during collection, where vaginal bacteria, including Lactobacillus, enter the urine specimen. This often occurs because female anatomy makes it challenging to collect a “clean catch” sample without some external bacterial introduction.
Alternatively, Lactobacillus may be present in the urinary tract, a condition called asymptomatic bacteriuria (ASB), meaning bacteria are present without causing symptoms. While Lactobacillus species are usually considered commensals (beneficial residents), certain species like L. delbrueckii or L. gasseri have, in rare cases, been identified as causative agents of urinary tract infections, particularly in individuals with weakened immune systems. Pregnancy itself increases a woman’s susceptibility to changes in the urinary tract, such as ureteral dilation and decreased bladder tone due to hormonal shifts like increased progesterone, which can lead to urinary stasis. This creates an environment where bacteria, if truly present in the urinary tract, might be more likely to multiply.
Potential Health Implications and Management During Pregnancy
The presence of bacteria in urine during pregnancy, including Lactobacillus if it represents a true presence rather than contamination, is taken seriously due to potential health implications. Untreated asymptomatic bacteriuria (ASB) in pregnant women can progress to more severe infections like acute pyelonephritis, a kidney infection, in 20-30% of cases. Pyelonephritis can lead to serious maternal complications such as sepsis and acute respiratory distress syndrome, and is associated with adverse pregnancy outcomes like preterm birth and low birth weight.
Accurate diagnosis is paramount, typically relying on a proper urine culture. Screening for ASB is recommended for all pregnant women, often at their first prenatal visit or between 12 and 16 weeks of gestation. A “clean-catch” midstream urine sample is collected and sent to a laboratory for culture to identify the type and quantity of bacteria present. If the initial culture shows Lactobacillus, particularly without other common urinary pathogens or white blood cells, and the patient has no symptoms, it may be considered contamination, and a repeat urine culture with careful collection technique might be advised.
Management depends on the diagnosis. If the presence of Lactobacillus is determined to be contamination, specific antibiotic treatment is generally not needed. However, if a true infection or ASB is confirmed, antibiotic treatment is recommended to reduce the risk of complications. Common antibiotics considered safe during pregnancy include nitrofurantoin, amoxicillin, amoxicillin-clavulanate, or cephalexin, typically for a duration of 3 to 7 days. It is important for pregnant individuals to consult their healthcare provider for accurate diagnosis and to follow their recommendations, as self-treating could disrupt the natural flora or delay appropriate management of a true infection.