# Case Report: Bloodstream infection due to Clostridium innocuum combined with Eggerthella lenta

## TL;DR

A patient developed a rare bloodstream infection with Clostridium innocuum and Eggerthella lenta after colorectal surgery, successfully treated with targeted antibiotics.

## Contribution

This case report highlights the identification and treatment of a rare co-infection with Clostridium innocuum and Eggerthella lenta using MALDI-TOF mass spectrometry.

## Key findings

- Clostridium innocuum and Eggerthella lenta can cause bloodstream infections after colorectal surgery.
- MALDI-TOF mass spectrometry enables rapid and economical identification of these rare anaerobic bacteria.
- Prompt and appropriate antibiotic treatment led to successful resolution of the infection.

## Abstract

The co-infection of Clostridium innocuum and Eggerthella lenta in bloodstream is uncommon. The choice of clinical drugs with which to treat such co-infection is limited, which is worthy of study.

A 58-year-old male patient was admitted to the Department of General Surgery of Huashan Hospital on May, for further treatment after chemotherapy for liver metastases from rectal cancer. Laparoscopic anterior rectal resection under general anesthesia, laparoscopic sigmoid-rectal anastomosis, laparoscopic mesenteric lymphadenectomy, laparoscopic temporary ileostomy, and segmentectomy were performed. On the 3rd day after surgery, the patient developed a fever with body temperature up to 38 °C accompanied by cough and yellow sputum. Chest CT showed possible bilateral lung inflammation and metastases. Empirical anti-infection and symptomatic and supportive treatment were given. The patient still had a fever, with a body temperature of up to 40.6 °C, accompanied by fear of cold and chills, abdominal pain and abdominal distension on physical examination, abdominal wound non-healing, visible purulent secretions, and increased C-reactive protein, procalcitonin, and other inflammatory indicators. Aerobic and anaerobic blood culture tests were performed. The anaerobic blood culture bottle was positive after incubation in the automatic incubator for 20 h. After 24 h of anaerobic subculture on blood plate. C. innocuum was identified by matter-assisted laser desorption/ionization time of Flight (MALDI-TOF) mass spectrometry. After anaerobic culture time was extended to 72 h, another small slow-growing colony was observed, and E. lenta was identified. The patient’s postoperative history of rectal cancer showed the possibility of intestinal colonizing bacteria invading the bloodstream and causing infection. According to pieces of literature and drug sensitivity tests in our center, vancomycin 1 g + piperacillin / tazobactam 4.5 g were administered every 12 h for anti-infection for 7 days. The patient’s fever peak decreased, and blood culture turned negative after reexamination, thus the treatment was considered to be effective. Because the patient also had an abdominal infection and lung infection, antibiotic therapy with cefoperazone sulbactam and levofloxacin was continued for 9 days, and the patient had no further fever and was discharged with improved condition.

Clostridium innocuum and E. lenta can cause bloodstream infection after colorectal surgery, and the above two rare anaerobic bacteria can be rapidly and economically identified by MALDI-TOF mass spectrometry. C. innocuum, and E. lenta isolated from bloodstream infections following colorectal surgery should be considered as pathogens and treated promptly and appropriately.