Eggerthelle lenta (E. lenta) is a gram-positive non-spore-bearing anaerobic bacilli that was first isolated from human feces by Arnold Eggerth in 1935.^[1] It is classified as an anaerobic eubacterium that cannot decompose glucose and tryptophan^[2] but can synthesize different kinds of steroid metabolism enzymes.^[3] On the basis of the high content of guanine + cytosine detected by 16S ribosomal RNA gene sequencing, its original name Eubacterium lentum was changed to E. lenta and concurrently transferred to its own distinct genus Eggerthella.^[4]E. lenta often exists in the gastrointestinal tract.^[5] Previous reports on E. lenta-induced sepsis were rare. Herein, we present a case of E. lenta-induced sepsis with abdominal pain as the main symptom.

A 65-year-old man was admitted to the Emergency Department of the First Hospital of Jilin University on July 5, 2021. Four days ago, he gradually developed pain in the right lower quadrant of the abdomen accompanied by fever and chills (peak temperature 39.3 ℃). He received anti-infection treatment with moxifloxacin at a local hospital which relieved the abdominal pain; however, there was no remission of fever. At the time of presenting to our hospital, his vital signs were as follows: temperature 36.8 ℃; blood pressure 135/67 mmHg (1 mmHg=0.133 kPa); pulse rate 65 beats/min, and respiratory rate 19 breaths/min. He was lucid and responsive. Abdominal examination revealed tenderness over the right lower quadrant of the abdomen; however, there was no rebound pain or muscle guarding. Cardiorespiratory and neurological examinations were unremarkable. The frequency of bowel sounds was 5 times/min. He had a past medical history of duodenal bulb ulcer for more than 10 years with no regular treatment. There was no history of hypertension, diabetes, or heart disease. He was a smoker for more than 40 years (30 cigarettes/d) and had been drinking for more than 20 years (0.25 kg/d). Routine blood parameters at admission were as follows: white blood cell count 8.29×10⁹/L; hemoglobin 164 g/L; platelet count 40×10⁹/L; serum aspartate aminotransferase 54 U/L; alanine aminotransferase 67.9 U/L; albumin 34.8 g/L; total bilirubin 59.1 µmol/L; direct bilirubin 30.2 µmol/L; indirect bilirubin 29.0 µmol/L; procalcitonin 54.36 ng/L; hypersensitive C-reaction protein 224.7 mg/L. Abdominal computed tomography (CT) showed multiple cysts in the liver, small cysts in the right kidney, and thrombosis in superior mesenteric veins and some branches. Lung CT showed bilateral interstitial pneumonia. Finally, based on Sepsis 3.0 definitions, with a definite infection and sequential organ failure assessment (SOFA) score of 5 (liver 2, blood 3), the diagnosis of sepsis was established.

After admission, cultures of blood, urine, and sputum were carried out immediately, followed by administration of empirical antibiotic therapy (meropenem) and fluid resuscitation. Gram-positive bacteria were detected in the anaerobic culture flask after 44 h of culture followed by inoculation on anaerobic culture medium (Berett-China blue AGAR medium). After two days of anaerobic culture, smooth, gray, and slightly raised colonies (diameter 0.25-0.75 mm) were observed (Figure 1). The mass spectrogram of the isolated strains was obtained by a Vitek mass spectrometry (MS) system of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) (Figure 2), which was highly consistent with the existing E. lenta in the database, with a confidence of 99.9%. In addition, the results of blood culture also suggested E. lenta six days after admission. Finally, ten days after admission, the result of blood culture turned out to be negative. There was resolution of abdominal pain and fever with C-reaction protein 53.71 mg/L, white blood cell count 10.20×10⁹/L, platelet count 253×10⁹/L, and serum bilirubin 23.8 µmol/L. The patient was cured and discharged.

E. lenta infection has been documented in patients with sepsis caused by various diseases, such as appendicitis,^[6] bedsore infection,^[7] intervertebral disc infection,^[8,9] urinary tract infection,^[10] frontal sinusitis,^[11] myositis pyogenes,^[9] and endometritis.^[12] In particular, patients with bedsores, immunocompromised status (such as steroid use, recent chemotherapy, end-stage renal disease, diabetes), cancer, gastrointestinal diseases (such as ulcerative colitis and Crohn’s disease), and congestive heart failure are much more prone to develop sepsis due to E. lenta.^[7,13⇓-15]E. lenta may cause severe gastrointestinal disease and mucosal inflammation or injury that promotes the entry of E. coli into the bloodstream and adjacent tissues. Our patient had a history of duodenal ulcer, which is considered a risk factor for him.

The identification of gram-positive bacteria using traditional methods is time-intensive and particularly difficult in case of slow-growing bacteria. In this case, MALDI-TOF MS was used for the identification of gram-positive bacteria. It is a new technology with a milder mode of ionization which ensures that the whole molecule remains intact during the ionization process, making it easier to identify different ionic components in the samples. Some laboratories apply two common systems for MALDI-TOF MS, including the Bruker MS system and Vitek MS system, to identify common pathogenic bacteria in clinical practice; the results showed that the accuracy of both systems reached 100% at the genus level, while the Vitek MS system had a higher accuracy at the species level.^[16] Moreover, metagenomic sequencing has also been applied in the identification of potential viral or bacterial infections.^[17]

In previous studies, the reported sensitivity of E. lenta to penicillin, ceftriaxone, and cefotaxime was only 21.9%. However, the sensitivity of E. lenta to clindamycin, ampicillin-sulbactam, metronidazole and carbapenems may reach up to 100%.^[13,16] Bo et al^[18] reported that frequent use of piperacillin-tazobactam (TZP) may accelerate the development of bacterial resistance. Furthermore, different minimum inhibitory concentrations of TZP had a significantly different impact on the 30-d mortality of patients; in addition, the use of TZP alone was found to be an independent risk factor for 30-d mortality.^{[13,15,19,20]} Our patient responded to meropenem with resolution of fever and significant improvement in infection indicators six days later, indicating the efficacy of the anti-infection therapy. However, Venugopal et al^[21] reported a 30-d mortality rate of 36.0% in a cohort of 25 patients with sepsis caused by E. lenta. In another study, the 30-d mortality of patients with E. lenta sepsis was 12%, and the one-year mortality was as high as 33%,^[22] indicating that E. lenta sepsis is associated with high mortality. Due to increased anaerobic resistance, antibiotic therapy should be based on the results of antimicrobial susceptibility test (AST), especially for severe infections caused by E. lenta.

Our patient showed quick recovery, possibly due to timely treatment. The main manifestations of E. lenta sepsis reported in the literature include fever, increased heart rate, increased levels of C-reaction protein and white blood cell count. No specific clinical manifestations were found.^[16] The presence of gram-positive bacilli in blood should be taken seriously and further laboratory studies should be carried out to avoid serious complications. In addition, early initiation of empirical antibiotic treatment should be followed by the use of antibiotics based on the AST results.

No specific clinical symptoms or laboratory indices related to E. lenta sepsis have been reported yet. However, owing to the high mortality, we must pay more attention to patients with digestive tract diseases accompanied by E. lenta sepsis. Empirical anti-infection treatment should be carried out as soon as possible. Timely determination of etiology can help avoid serious complications. In addition, with the increase in drug-resistant bacteria, antibiotics should be used based on the results of AST.

Funding: None.

Ethical approval: This study was approved by the Ethics Committee of the First Hospital of Jilin University. Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.

Conflicts of interest: All authors declare that the research was conducted in the absence of any commercial or financial relationships. The authors report no conflicts of interest for this work.

Contributors: LCS and WLX contributed equally to this work. All authors made a significant contribution to the work reported.