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Bacteremia With Anaerobic Bacteria and Association With Colorectal Cancer: A Population-based Cohort Study
Ulrik S Justesen1,2, Stig L Nielsen3,4, Thøger G Jensen1,2
1Department of Clinical Microbiology, Odense University Hospital, Odense, Denmark.
Summary
Bacteremia from certain gut bacteria, beyond known associations, significantly increases colorectal cancer risk. This finding highlights the need for colorectal screening in patients with specific bloodstream infections.
Area of Science:
- Microbiology and Oncology
- Gut Microbiome and Cancer Research
- Infectious Disease Epidemiology
Background:
- Established link between bovis group streptococci or Clostridium septicum bacteremia and colorectal cancer (CRC).
- Need to explore associations between CRC and bacteremia involving other gut microbiota members.
- Limited understanding of the broader spectrum of bacteria linked to CRC risk.
Purpose of the Study:
- To investigate the association between bacteremia with various gut bacteria and the risk of CRC diagnosis.
- To identify specific bacterial species within the gut microbiota that may serve as indicators for CRC.
- To compare the CRC risk associated with these bacteria against a baseline of blood culture-negative cases.
Main Methods:
- Population-based cohort study including approximately 2 million individuals from 2007-2016.
- Analysis of 45,774 bacteremia episodes and 231,387 blood culture-negative cases.
- Utilized Cox's regression analysis with hazard ratios (HRs) and 95% confidence intervals (CIs), linking bacteremia data with the Danish central register for CRC.
Main Results:
- Confirmed increased CRC risk for bovis group streptococci (HR: 8.46) and C. septicum (HR: 76.2).
- Identified significant associations between CRC and bacteremia with Bacteroides ovatus (HR: 20.3), Bacteroides uniformis (HR: 16.2), Clostridium tertium (HR: 13.9), Fusobacterium spp. (HR: 8.51), and Gram-positive anaerobic cocci (HR: 10.9).
- Compared to blood culture-negative cases (0.4% CRC risk), these specific bacterial bacteremias showed substantially elevated CRC risks.
Conclusions:
- Bacteremia involving specific anaerobic gut bacteria is strongly associated with a high risk of CRC diagnosis.
- These findings underscore the importance of considering colorectal workup in patients with such bacteremias.
- This diagnostic strategy may also aid in detecting adenomas and other premalignant conditions, though not directly studied here.
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