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The Abundant Free Living Amoeba, Acanthamoeba polyphaga, Increases the Survival of Campylobacter jejuni in Milk and Orange Juice
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
Linnéuniversitetet i Kalmar. (Zoonotic Ecology and Epidemiology)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Campylobacter jejuni is a common cause of human bacterial diarrhea in most parts of the world. Most C. jejuni infections are acquired from contaminated poultry, milk and water. Due to health care costs and human suffering, it is important to identify all possible sources of infection. Unpasteurized milk has been associated with several outbreaks of C. jejuni infection. Campylobacter has been identified on fresh fruit and other gastrointestinal pathogens such as Salmonella, E. coli O157:H7 and Cryptosporidium have been involved in fruit juice outbreaks. C. jejuni is sensitive to the acidic environment of fruit juice, but co-cultures with A. polyphaga have previously been shown to protect C. jejuni at low pH. In this study we found that co-culture with A. polyphaga  prolonged the C. jejuni survival both in milk and juice. The effect of co-culture was most pronounced in juice stored at room temperature. On the other hand, we found that A. polyphaga did not have any effect on C. jejuni survival during pasteurization of milk or orange juice, indicating that this is a good method for eliminating C. jejuni in these products. In conclusion, amoebae associated C. jejuni in milk and juice might cause C. jejuni infections.

 

 

 

Keyword [en]
juice, unpasteurized milk, Campylobacter, Acanthamoeba
National Category
Medical and Health Sciences
Research subject
Infectious Diseases
Identifiers
URN: urn:nbn:se:uu:diva-255770OAI: oai:DiVA.org:uu-255770DiVA: diva2:823557
Funder
Swedish Research Council Formas, 2220-8779-120, 221-2012-1442
Available from: 2015-06-18 Created: 2015-06-18 Last updated: 2015-09-07
In thesis
1. Amoebae as Hosts and Vectors for Spread of Campylobacter jejuni
Open this publication in new window or tab >>Amoebae as Hosts and Vectors for Spread of Campylobacter jejuni
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Campylobacter jejuni is the leading bacterial cause of gastrointestinal diarrheal disease in humans worldwide. This zoonotic pathogen has a complex epidemiology due to its presence in many different host organisms. The overall aim of this thesis was to explore the role of amoebae of the genus Acanthamoeba as an intermediate host and vector for survival and dissemination of C. jejuni. Earlier studies have shown that C. jejuni can enter, survive and replicate within Acanthamoebae spp. In this thesis, I have shown that C. jejuni actively invades Acanthamoeba polyphaga. Once inside, C. jejuni could survive within the amoebae by avoiding localization to degradative lysosomes. We also found that A. polyphaga could protect C. jejuni in acid environments with pH levels far below the range in which the bacterium normally survives. Furthermore, low pH triggered C. jejuni motility and invasion of A. polyphaga. In an applied study I found that A. polyphaga also could increase the survival of C. jejuni in milk and juice both at room temperature and at +4ºC, but not during heating to recommended pasteurization temperatures. In the last study we found that forty environmental C. jejuni isolates with low bacterial concentrations could be successfully enriched using the Acanthamoeba-Campylobacter coculture (ACC) method. Molecular genetic analysis using multilocus sequence typing (MLST) and sequencing of the flaA gene, showed no genetic changes during coculture. The results of this thesis have increased our knowledge on the mechanisms behind C. jejuni invasion and intracellular survival in amoebae of the genus Acanthamoeba. By protecting C. jejuni from acid environments, Acanthamoebae could serve as important reservoirs for C. jejuni e.g. during acid sanitation of chicken stables and possibly as vectors during passage through the stomach of host animals. Furthermore, Acanthamoeba spp. could serve as a vehicle and reservoir introducing and protecting C. jejuni in beverages such as milk and juice. Validation of the ACC method suggests that it is robust and could be used even in outbreak investigations where genetic fingerprints are compared between isolates. In conclusion, Acanthamoeba spp. are good candidates for being natural hosts and vectors of C. jejuni.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2015. 50 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1115
Keyword
Amoebae-Bacteria interactions; Campylobacter jejuni; epidemiology; environmental stress; low pH; Acanthamoeba; coculture; intracellular trafficking; bacterial survival; beverages; ACC-method; enrichment; genetic stability; Trojan horse; reservoir; host; vector
National Category
Medical and Health Sciences
Research subject
Infectious Diseases
Identifiers
urn:nbn:se:uu:diva-255804 (URN)978-91-554-9276-2 (ISBN)
Public defence
2015-09-10, A1:111a, Biomedicinskt Centrum, Husargatan 3, Ing C7:2, Uppsala, 09:00 (Swedish)
Opponent
Supervisors
Funder
Swedish Research Council Formas, 2220-8779-120, 221-2012-1442Medical Research Council of Southeast Sweden (FORSS)Swedish Research Council Formas, 2007-438Swedish Research Council for Environment, Agricultural Sciences and Spatial PlanningThe Crafoord Foundation
Available from: 2015-08-19 Created: 2015-06-18 Last updated: 2015-09-07

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