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

Abstract

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.

Keywords: 16S rDNA sequencing; Catabacter hongkongensis; phylogeny; sepsis.

Figure 1

Phylogenetic analysis of Catabacter hongkongensis identified in blood cultures. Phylogenetic tree drawn up by ML-Method on 631 bases, on available sequences. An arrow indicates strains of Catabacter hongkongensis responsible for lethal infections. No significant association of these sequences could be obtained in terms of severity (p > 0.05) as no clustering could be statistically observed. No significant clustering could be observed regarding the antibiotic sensitivity testing (AST) profile using 16S rDNA sequencing phylogenetic analysis (p > 0.05).