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Updated: Jul 6, 2026
Culture Methods to Determine the Limit of Detection and Survival in Transport Media of Campylobacter Jejuni in Human Fecal Specimens
Published on: March 10, 2020
Identification and characterization of an invasive, hyper-aerotolerant Campylobacter jejuni strain causing bacteremia
Ximin Zeng1, Kevin M Lloyd2,3, Rana F Hamdy2,3
1Department of Animal Science, University of Tennessee, Knoxville, Tennessee, USA.
Insights
A novel hyper-aerotolerant Campylobacter jejuni strain was identified in a human bloodstream infection. This finding highlights the potential for increased pathogen survival and transmission in the environment.
Area of Science:
- Microbiology
- Infectious Diseases
- Genomics
Background:
- Campylobacter jejuni is a major cause of human gastroenteritis.
- Invasive strains can cross the gut-blood barrier, leading to bacteremia.
- Hyper-aerotolerant (HAT) C. jejuni, with enhanced oxygen tolerance, has been found in animal and human intestines, but not previously reported in human bacteremia.
Background:
Campylobacter jejuni is a leading pathogen causing gastroenteritis in humans. Invasive C. jejuni strains crossing the gut-blood barrier can cause bacteremia. Despite its microaerophilicity (preferring <5% O2 atmosphere), hyper-aerotolerant (HAT) C. jejuni has recently been isolated from intestines in poultry and humans. Elevated aerotolerance may enhance C. jejuni survival in the ecosystem, thereby promoting its transmission. However, invasive HAT isolates of C. jejuni have not been reported in bacteremia in humans.
Case Summary:
A C. jejuni strain (CNH-HAT-1) was isolated from a 7% CO2 (~16% O2) atmosphere subculture of an aerobic blood culture from a 5-year-old boy with B-cell acute lymphoblastic leukemia presenting with bloody stool, fever, and neutropenia. The organism identification was determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S-rRNA sequencing. HAT phenotype of this isolate was confirmed by aerotolerance testing. Belonging to the ST-21 clonal complex, CNH-HAT-1 is phylogenetically close to recently reported invasive C. jejuni sheep abortion strains and some bacteremia-associated strains. CNH-HAT-1 possesses a CJIE-1 prophage element, a functional enterobactin receptor CfrB, and G250A mutation in the major outer-membrane protein PorA, which likely contributes to C. jejuni invasiveness. CNH-HAT-1 is resistant to penicillins/cephalosporins but susceptible to aminoglycosides, fluoroquinolones, and macrolides. The patient improved with intravenous gentamicin, followed by enteral therapy with azithromycin.
Conclusion:
We identified a novel invasive bloodstream C. jejuni strain proven in vitro to be HAT, shedding light on key genomic features linking with its pathogenesis. Given its enhanced survival of HAT C. jejuni in ecosystem, a clinical microbiology lab should be vigilant with detecting them from blood cultures.
