"Driver or passenger" : an integrated epidemiological and experimental perspective on the association between nontyphoidal salmonella infection and colon cancer

A growing body of scientific literature documents a putative role of commensal and pathogenic bacteria in the initiation and progression of cancers. One such bacterium is nontyphoidal Salmonella (NTS), which has been associated with colon cancer in a few studies. Yet, a lot is still unknown about the magnitude and underlying mechanisms, including the necessary conditions or ‘prerequisites’, of the potential colon carcinogenesis promoting effects of Salmonella. In this thesis, we performed several complementary analyses based on both experimental and epidemiological study designs. Significant excess risk of NTS infection was observed among several occupational groups including those involving contact with live animals or animal manure and animal-derived food sale. The risk of colon cancer was not elevated in these groups. Also, no clear association between NTS and colon cancer was found in a Danish cohort. Two-fold infection of mouse embryonic fibroblasts (MEFs) with a low dose of NTS was more successful than a single high-dose infection (i.e. more and larger colonies). Substantial variation between NTS isolates was found in their capacity to infect MEFs and to induce cellular transformation, with a tendency towards higher transformation efficiency in isolates originating from people who were diagnosed with colon cancer later in life.Dutch Cancer Society (KWF); ZonMWLUMC / Geneeskund

Bacterial and parasitic pathogens as risk factors for cancers in the gastrointestinal tract: a review of current epidemiological knowledge

The oncogenic potential of viral infections is well established and documented for many years already. However, the contribution of (commensal) bacteria and parasites to the development and progression of cancers has only recently gained momentum, resulting in a rapid growth of publications on the topic. Indeed, various bacteria and parasites have been suggested to play a role in the development of gastrointestinal cancer in particular. Therefore, an overview of the current epidemiological knowledge on the association between infections with bacteria and parasites and cancers of the gastrointestinal tract is needed. In this review, we summarized the methodological characteristics and main results of epidemiological studies investigating the association of 10 different bacteria (Bacteroides fragilis, Campylobacter spp., Clostridium spp., Enterococcus faecalis, Escherichia coli, Fusobacterium nucleatum, Porphyromonas gingivalis, non-typhoidal Salmonella, Salmonella Typhi, and Streptococcus spp.) and three parasites (Cryptosporidium spp., Schistosoma spp., and Strongyloides stercoralis) with gastrointestinal cancer. While the large body of studies based on microbiome sequencing provides valuable insights into the relative abundance of different bacterial taxa in cancer patients as compared to individuals with pre-malignant conditions or healthy controls, more research is needed to fulfill Koch's postulates, possibly making use of follow-up data, to assess the complex role of bacterial and parasitic infections in cancer epidemiology. Studies incorporating follow-up time between detection of the bacterium or parasite and cancer diagnosis remain valuable as these allow for estimation of cause-effect relationships.Chemical Immunolog

Zika virus infection in 18 travellers returning from Surinam and the Dominican Republic, The Netherlands, November 2015–March 2016

Purpose: We report 18 cases of confirmed Zika virus (ZIKV) infection in travellers returning to the Netherlands from Surinam (South America, bordering northern Brazil) and the Dominican Republic. Methods: In a multi-centre study, we collected epidemiological, virological and clinical characteristics, as well as data on travel history, underlying illness and laboratory results of the 18 imported ZIKV infection cases using a standardised form. Results: Most cases had a self-limiting course of disease, two patients developed complications, one had Guillain–Barré and another had severe thrombocytopenia. Four patients had underlying illness. One of the reported cases was pregnant. Three of 13 patients tested had a weak-positive result for dengue IgM. The majority of patients were born in Suriname and/or visiting friends and relatives (VFR). Conclusions: Providing pre-travel advice among travellers, especially VFR travellers, is needed to enhance the use of preventive measures against ZIKV infection. Further evidence on health risks associated with ZIKV infection is urgently needed

"Driver or passenger" : an integrated epidemiological and experimental perspective on the association between nontyphoidal salmonella infection and colon cancer

A growing body of scientific literature documents a putative role of commensal and pathogenic bacteria in the initiation and progression of cancers. One such bacterium is nontyphoidal Salmonella (NTS), which has been associated with colon cancer in a few studies. Yet, a lot is still unknown about the magnitude and underlying mechanisms, including the necessary conditions or ‘prerequisites’, of the potential colon carcinogenesis promoting effects of Salmonella. In this thesis, we performed several complementary analyses based on both experimental and epidemiological study designs. Significant excess risk of NTS infection was observed among several occupational groups including those involving contact with live animals or animal manure and animal-derived food sale. The risk of colon cancer was not elevated in these groups. Also, no clear association between NTS and colon cancer was found in a Danish cohort. Two-fold infection of mouse embryonic fibroblasts (MEFs) with a low dose of NTS was more successful than a single high-dose infection (i.e. more and larger colonies). Substantial variation between NTS isolates was found in their capacity to infect MEFs and to induce cellular transformation, with a tendency towards higher transformation efficiency in isolates originating from people who were diagnosed with colon cancer later in life.</p

"Driver or passenger" : an integrated epidemiological and experimental perspective on the association between nontyphoidal salmonella infection and colon cancer

A growing body of scientific literature documents a putative role of commensal and pathogenic bacteria in the initiation and progression of cancers. One such bacterium is nontyphoidal Salmonella (NTS), which has been associated with colon cancer in a few studies. Yet, a lot is still unknown about the magnitude and underlying mechanisms, including the necessary conditions or ‘prerequisites’, of the potential colon carcinogenesis promoting effects of Salmonella. In this thesis, we performed several complementary analyses based on both experimental and epidemiological study designs. Significant excess risk of NTS infection was observed among several occupational groups including those involving contact with live animals or animal manure and animal-derived food sale. The risk of colon cancer was not elevated in these groups. Also, no clear association between NTS and colon cancer was found in a Danish cohort. Two-fold infection of mouse embryonic fibroblasts (MEFs) with a low dose of NTS was more successful than a single high-dose infection (i.e. more and larger colonies). Substantial variation between NTS isolates was found in their capacity to infect MEFs and to induce cellular transformation, with a tendency towards higher transformation efficiency in isolates originating from people who were diagnosed with colon cancer later in life.</p

The role of co-morbidities in the development of an AEFI after COVID-19 vaccination in a large prospective cohort with patient-reported outcomes in the Netherlands

The effect of a preexisting comorbidity on the occurrence of adverse events after immunization (AEFIs) has been studied poorly. In this longitudinal cohort study, we assess the association between co-morbidities and the occurrence of AEFIs after COVID-19 vaccination. Also, we described the occurrence of flare-ups and their manifestation after COVID-19 vaccination in people with rheumatic diseases. We performed multivariable logistic regression to investigate the association between the occurrence of AEFIs and 10 common comorbidities using patient-reported data from people vaccinated with the AstraZeneca, Johnson&Johnson, Moderna, or Pfizer vaccine. Occurrence of any AEFI, injection site reactions, headache, fatigue, and/or malaise was significantly associated with presence of comorbidities, including psychological disorders, musculoskeletal disorders, and endocrine disorders after the first and second doses (OR ranges 1.23–1.77). One participant with rheumatoid arthritis experienced a flare-up after receiving the first dose of the AstraZeneca vaccine. The results showed that the odds of reporting an AEFI after COVID-19 vaccination is significantly higher in the presence of some comorbidities whilst flare-ups are uncommon after receiving COVID-19 vaccination in people with rheumatic disease. In-depth research is needed to validate our results and unravel the observed associations from a mechanistic perspective.</p

Repetitive non-typhoidal Salmonella exposure is an environmental risk factor for colon cancer and tumor growth

During infection, Salmonella hijacks essential host signaling pathways. These molecular manipulations disrupt cellular integrity and may induce oncogenic transformation. Systemic S. Typhi infections are linked to gallbladder cancer, whereas severe non-typhoidal Salmonella (NTS) infections are associated with colon cancer (CC). These diagnosed infections, however, represent only a small fraction of all NTS infections as many infections are mild and go unnoticed. To assess the overall impact of NTS infections, we performed a retrospective serological study on NTS exposure in patients with CC. The magnitude of exposure to NTS, as measured by serum antibody titer, is significantly positively associated with CC. Repetitively infecting mice with low NTS exposure showed similar accelerated tumor growth to that observed after high NTS exposure. At the cellular level, NTS preferably infects (pre-)transformed cells, and each infection round exponentially increases the rate of transformed cells. Thus, repetitive exposure to NTS associates with CC risk and accelerates tumor growth.Chemical Immunolog