First report of sepsis due to Catabacter hongkongensis in an Italian patient

Peritonitis with bacteremia due to Christensenella hongkongensis identified via ribosomal RNA sequencing in a Japanese patient with advanced colorectal adenocarcinoma: A case report

Background

Christensenella hongkongensis is an obligately anaerobic, catalase-positive, motile, non-sporulating, gram-positive coccobacillus. Human infections are rare and have not been previously reported in Japan. Herein, we report the first case of perforated peritonitis with C. hongkongensis bacteremia in Japan.

Case presentation

A 61-year-old Japanese man with advanced colorectal adenocarcinoma presented with fever and abdominal pain. Abdominal computed tomography revealed a low-density area with thinning of the sigmoid colon wall and air outside the intestinal tract, which was diagnosed as perforated peritonitis. Cultures of the ascitic fluid isolated Bacteroides fragilis, Bacteroides eggerthii, Parabacteroides distasonis, Enterococcus avium, and Candida albicans. Gram-positive rods were detected in the blood culture on admission after 4 days. The isolate was identified as C. hongkongensis via 16S ribosomal RNA (16S rRNA) sequencing. The patient underwent open abdominal washout and drainage via a transverse colon bifurcation colostomy. Intravenous meropenem (3 g/day) was administered for 5 days, followed by intravenous piperacillin-tazobactam (9 g/day) for 6 days, and then levofloxacin (500 mg/day) and metronidazole (1500 mg/day) intravenously for 15 days. Postoperatively, the patient gradually recovered. He was transferred to another palliative care hospital on day 38 after admission for worsening advanced colorectal cancer condition.

Conclusion

Bacteremia caused by C. hongkongensis is rare. 16S rRNA sequencing should be considered for the identification of gram-positive anaerobic rods that are difficult to diagnose by conventional methods.

A fatal case associated with Catabacter hongkongensis bacteremia in lung cancer patient: A case report

Catabacter hongkongensis is a bacterium first isolated in 2007 and has since been detected in the blood of about fifteen patients with disease such as gastrointestinal malignancy, intestinal obstruction, or acute intestinal infection. We describe herein the case of a patient newly diagnosed with metastatic lung cancer, who died from a fatal infection possibly related to Catabacter hongkongensis bacteremia. By reviewing all cases reported in the literature, our case report supports that this infection is associated with a very high mortality in cancer patients.

Catabacter hongkongensis bacteremia identified by direct metagenomic sequencing of positive blood culture fluid, first case report in the US

Catabacter hongkongensis, an increasingly recognized bacteria in clinical samples, was identified by direct metagenomic sequencing of positive blood culture fluid from a 55-year-old patient with colonic perforation. The bacteremia was cleared by both antibiotic treatment and surgical intervention. This is the first case report of C. hongkongensis infection in the US.

Reclassification of Catabacter hongkongensis as Christensenella hongkongensis comb. nov. based on whole genome analysis

The genera Catabacter (family 'Catabacteraceae') and Christensenella (family Christensenellaceae) are close relatives within the phylum Firmicutes. Members of these genera are strictly anaerobic, non-spore-forming and short straight rods with diverse phenotypes. Phylogenetic analysis of 16S rRNA genes suggest that Catabacter splits Christensenella into a polyphyletic clade. In an effort to ensure that family/genus names represent monophyletic clades, we performed a whole-genome based analysis of the genomes available for the cultured representatives of these genera: four species of Christensenella and two strains of Catabacter hongkongensis. A concatenated alignment of 135 shared protein sequences of single-copy core genes present in the included strains indicates that C. hongkongensis is indeed nested within the Christensenella clade. Based on their evolutionary relationship, we propose the transfer of Catabacter hongkongensis to the genus Christensenella as Christensenella hongkongensis comb. nov.

Phylogeny of Catabacter hongkongensis Strains Responsible for Bacteremia Is Not Associated with Clinical Outcomes or Therapeutic Efficacy

Catabacter hongkongensis is a Gram-positive rod, isolated in 2007 in blood culture. Fewer than 15 infections have been reported. Herein, we present a lethal case of bacteremia due to C. hongkongensis identified through phylogenetic analyses. A woman was found unconscious in a context of chronic diarrhea. An abdominal abscess with a hydroaeric level was discovered, associated with sigmoid adenocarcinoma and peritoneal carcinomatosis. Despite hospitalization in an ICU and the adaptation of antibiotic therapy, the patient died. Blood cultures were positive in the final stage of the disease (>60 h). Identification of C. hongkongensis was performed using 16S rDNA sequencing. Phylogenetic analyses did not enable classification of these strains according to clinical outcome or the antibiotic sensitivity to treatment. In this case, bacteria were difficult to isolate and MALDI-TOF remained non-contributive. As strains are resistant to probabilistic treatments, addition of metronidazole or vancomycin could optimize clinical management, highlighting the benefit of rapid molecular identification by sequencing.