Bacteremia With Anaerobic Bacteria and Association With Colorectal Cancer: A Population-based Cohort Study

• Published in: Clinical infectious diseases Vol. 75; no. 10; pp. 1747 - 1753
• Main Authors: Justesen, Ulrik S, Nielsen, Stig L, Jensen, Thøger G, Dessau, Ram B, Møller, Jens K, Coia, John E, Andersen, Steen L, Pedersen, Court, Gradel, Kim O
• Format: Journal Article
• Language: English
• Published: US Oxford University Press 14-11-2022
• Subjects: Bacteremia - microbiology; Bacteria, Anaerobic; Cohort Studies; Colorectal Neoplasms - diagnosis; Colorectal Neoplasms - epidemiology; Humans; Streptococcus pyogenes; colorectal cancer; cohort study; anaerobic bacteria; gut microbiota; bacteremia
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/ciac259

Abstract
Background
There is a well-described association between bacteremia with bovis group streptococci or Clostridium septicum and an increased probability of a colorectal cancer (CRC) diagnosis. We wanted to investigate the existence of a similar association between CRC and bacteremia with other bacteria belonging to the gut microbiota..
Methods
A population based cohort study in a population about 2 million people including 45 774 bacteremia episodes and 231 387 blood culture negative cases was performed in the Region of Southern Denmark and Region Zealand from 2007–2016. Episodes of bacteremia were combined with the Danish central register for CRC. We performed Cox’s regression analysis with hazard ratios (HRs) and 95% confidence intervals (CIs).
Results
The study results confirmed previous findings of an increased risk of a CRC diagnosis after bacteremia with the bovis group streptococci (risk within a year: 4.3%; HR [95% CI]: 8.46 [3.51–20.4]) or C. septicum (20.8%; 76.2 [42.0–138]). Furthermore, Bacteroides ovatus (6.7%; 20.3 [5.04–81.8]), Bacteroides uniformis (5.4%; 16.2 [4.02–65.7]), Clostridium tertium (3.6 %; 13.9 [1.96–99.4]), Fusobacterium spp. (excluding F. necrophorum) (3.0 %; 8.51 [2.73–26.5]), and Gram-positive anaerobic cocci (3.6 %; 10.9 [4.50–26.3]) were also associated with an increased risk of a CRC diagnosis compared to patients with negative blood cultures (0.4%).
Conclusions
Bacteremia with specific gut microbiota anaerobic bacteria is associated with a high risk of a diagnosis of CRC, indicating the need for colorectal workup. Importantly, this strategy also holds the possible additional benefit of detecting adenomas or other premalignant conditions, which were not included in the present study.
By combining complete population-based data for bacteremia and colorectal cancer (CRC), we identified several bacterial species, primarily anaerobic bacteria that belong to the gut microbiota, that were associated with a CRC diagnosis (up to >20%) within 1 year following bacteremia.