Genomic and clinical characteristics of campylobacteriosis in Australia
Bibliographic record
Abstract
Abstract Campylobacter spp. are a common cause of bacterial gastroenteritis in Australia, primarily acquired from contaminated meat. We investigated the relationship between genomic virulence characteristics and the severity of campylobacteriosis, hospitalisation, and other host factors. We recruited 571 campylobacteriosis cases from three Australian states and territories (2018–2019). We collected demographic, health status, risk factors, and self-reported disease data. We whole genome sequenced 422 C. jejuni and 84 C. coli case isolates along with 616 retail meat isolates. We classified case illness severity using a modified Vesikari scoring system, performed phylogenomic analysis, and explored risk factors for hospitalisation and illness severity. On average, cases experienced a 7.5-day diarrhoeal illness with additional symptoms including stomach cramps (87.1%), fever (75.6%), and nausea (72.0%). Cases aged ≥75 years had milder symptoms, lower Vesikari scores, and higher odds of hospitalisation compared to younger cases. Chronic gastrointestinal illnesses also increased odds of hospitalisation. We observed significant diversity among isolates, with 65 C. jejuni and 21 C. coli sequence types. Antimicrobial resistance genes were detected in 20.4% of isolates, but multidrug resistance was rare (0.04%). Key virulence genes such as cdtABC ( C. jejuni ) and cadF were prevalent (>90% presence) but did not correlate with disease severity or hospitalisation. However, certain genes appeared to distinguish human C. jejuni cases from food source isolates. Campylobacteriosis generally presents similarly across cases, though some are more severe. Genotypic virulence factors identified in the literature to-date do not predict disease severity but may differentiate human C. jejuni cases from food source isolates. Host factors like age and comorbidities have a greater influence on health outcomes than virulence factors. Author summary This study focused on Campylobacter, a common cause of gastroenteritis in Australia. We explored the relationship between Campylobacter’s genomic characteristics and disease severity, hospitalisation, and host-related factors. In 2018 – 2019, we collected data from 571 campylobacteriosis cases from Eastern Australia, focusing on demographics, health status, risk factors, and self-reported symptoms. We sequenced 422 C. jejuni and 84 C. coli case isolates and 616 retail meat isolates. We used a modified Vesikari scoring system to assess illness severity, performed phylogenomic analysis, and explored hospitalisation and severity risk factors. Cases experienced an average 7.5-day period of diarrhoea with additional symptoms including stomach cramps, fever, and nausea. Older individuals (75+ years) had milder symptoms but a higher chance of hospitalisation. Those with chromic gastrointestinal conditions faced increased hospitalisation odds. Case isolates showed considerable diversity. Antimicrobial resistance genes were detected in some isolates, but multidrug resistance was rare. Virulence genes did not predict severity or hospitalisation, but some genes did differentiate between case and food source C. jejuni isolates. Host-related factors including age and comorbidities are more important in determining health outcomes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".