Eggerthella lenta is a gram-positive, non-spore-forming, anaerobic bacterium commonly found in the human digestive system. It is a natural part of the diverse community of microorganisms that inhabit the human gut, known as the commensal gut microbiota.
Role in the Human Gut
Within the gut, Eggerthella lenta performs metabolic activities. One notable function involves its ability to process certain plant-derived compounds, such as the soy isoflavone daidzein. The bacterium can convert daidzein into equol, a metabolite that some studies suggest may have beneficial health effects. This highlights its role in the biotransformation of dietary substances within the intestinal environment.
Eggerthella lenta is recognized for its capacity to inactivate the cardiac drug digoxin. Digoxin is a medication used to treat certain heart conditions, and its effectiveness relies on specific concentrations in the body. The bacterium achieves this inactivation by converting digoxin into dihydrodigoxin, a less active metabolite, which can significantly alter the drug’s intended therapeutic effects. This metabolic activity can have important clinical implications for patients who rely on digoxin therapy, potentially reducing the drug’s efficacy.
Infections Caused by Eggerthella lenta
Eggerthella lenta, typically a harmless resident of the gut, can become an opportunistic pathogen, causing infections when it spreads beyond its usual habitat or when an individual’s immune system is compromised. These infections often originate from the gastrointestinal tract, though the bacterium can spread to other areas of the body. When it causes disease, it is frequently associated with polymicrobial infections.
Eggerthella lenta is most commonly linked to bloodstream infections, known as bacteremia, and intra-abdominal abscesses. Other reported infection sites include skin and soft tissue, surgical sites, and less frequently, the urinary or biliary tracts. These infections can range in severity, with bloodstream infections sometimes being life-threatening and carrying a significant mortality rate.
Several factors increase an individual’s susceptibility to Eggerthella lenta infections. Common risk factors include recent abdominal surgery, and underlying gastrointestinal conditions like inflammatory bowel disease (IBD) or cancers. Individuals with weakened immune systems, diabetes mellitus, or chronic kidney disease are also more prone to these infections. Advanced age is another factor associated with an increased risk of E. lenta bacteremia.
Diagnosis and Treatment
Identifying Eggerthella lenta infections presents challenges for medical laboratories. As an anaerobe, the bacterium requires special oxygen-free conditions to grow in laboratory cultures, which can delay diagnosis. Traditional identification methods have been difficult, leading to underrecognition. However, newer techniques like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) are now improving the speed and accuracy of identification.
Treatment for Eggerthella lenta infections typically involves antibiotic therapy, often combined with surgical drainage for abscesses. Common antibiotics found to be effective include metronidazole, amoxicillin-clavulanate, and carbapenems such as meropenem or ertapenem. Surgical intervention, particularly for abscesses, has been shown to offer a benefit in patient outcomes.
A notable concern in treating Eggerthella lenta infections is the bacterium’s varying antibiotic susceptibility. Some strains exhibit resistance to commonly used antibiotics, including penicillin and sometimes clindamycin or moxifloxacin. There are also reports of resistance to ceftriaxone, and empiric use of piperacillin-tazobactam has been associated with increased mortality in some studies. Therefore, susceptibility testing is important to guide appropriate antibiotic selection, though access to such specialized testing for anaerobes may be limited to specific reference laboratories.