Phenotypic Virulence Characteristics, Virulence Gene Profiles and ERIC-PCR Diversity of Urinary Enterococcus faecalis Isolates from Pregnant Women in the Federal Capital Territory, Nigeria
This study characterizes urinary *Enterococcus faecalis* isolates from pregnant women in Nigeria's Federal Capital Territory, revealing high frequencies of biofilm formation and extracellular enzyme production, diverse virulence gene profiles, and significant genetic heterogeneity that underscore the need for expanded molecular surveillance.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
Inside the human body, the urinary tract is usually a sterile highway where waste flows out without interruption. But during pregnancy, the physical changes that prepare a woman for childbirth can slow this flow, creating pockets where bacteria can settle and multiply. Among the many microbes that might take advantage of this situation, Enterococcus faecalis is a particularly adaptable survivor. It is a bacterium that thrives in the gut but can easily move to the urinary tract, where it has a toolkit for causing trouble. This toolkit includes the ability to stick to surfaces, build protective shields around itself, and produce enzymes that can damage tissue. When these bacteria infect a pregnant woman, the risks extend beyond the mother; the bacteria can pass to the newborn during delivery, potentially causing serious illness in the infant. Understanding exactly how these bacteria behave and how they vary from one person to another is essential for protecting both mother and child, yet scientists have known very little about the specific strains circulating among pregnant women in Nigeria.
To fill this gap, a team of researchers traveled to the Federal Capital Territory in Nigeria to investigate the bacteria found in the urine of pregnant women. They worked with women attending prenatal clinics across six different local government areas, collecting clean urine samples from nearly six hundred participants. From these samples, they isolated twenty-seven distinct strains of Enterococcus faecalis. The scientists then put these bacteria through a series of tests to see what they were capable of doing in a laboratory setting. They looked for the ability to form biofilms, which are slimy, protective layers that bacteria build to stick to surfaces and resist cleaning; they checked for the production of gelatinase and protease, which are enzymes that can break down proteins in the body; and they observed whether the bacteria could destroy red blood cells, a sign of a specific type of toxin activity.
The results showed that these bacteria were indeed well-equipped for survival. More than half of the strains tested were able to form biofilms, and the vast majority produced the protein-digesting enzymes. The researchers found a strong link between the production of gelatinase and protease, suggesting that bacteria capable of making one were very likely to make the other. To understand the genetic makeup behind these behaviors, the team selected ten of the isolates for a deeper look. They confirmed the species using a genetic test and then screened for specific genes known to help the bacteria stick to tissues, clump together, or produce toxins. They found that genes associated with sticking to surfaces and clumping were present in half of the tested strains, while genes linked to toxin production were found in fewer. Interestingly, the number of these harmful genes a bacterium carried did not perfectly predict how much biofilm it produced, indicating that the relationship between a bacterium's genetic code and its actual behavior is complex.
To see if these ten bacteria were all the same or if they represented different families, the researchers used a technique called ERIC-PCR, which acts like a genetic fingerprinting method. Instead of finding a single dominant strain that had spread to everyone, they discovered a high degree of diversity. The ten isolates fell into four distinct groups and produced nine different genetic patterns. This finding suggests that the bacteria causing infections in these pregnant women are not clones of a single source but rather a mix of different strains circulating in the community. The study concludes that while these bacteria frequently display traits that make them dangerous, such as biofilm formation and enzyme production, the specific genetic profiles vary widely. This diversity means that a one-size-fits-all approach to treatment or prevention may not work, and it highlights the need for broader, ongoing surveillance to track how these bacteria evolve and spread among vulnerable populations.
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