The genus Arcobacter was established in 1991 (Vandamme P. E.-1., 1991), and some members of this genus, including Arcobacter butzleri, Arcobacter cryaerophilus,andArcobacter skirrowii, are associated with humans diseases. This genus have been detected and isolated worldwide in the last two decades, and numerous studies have analysed its prevalence and pathogenicity. However, its potential as foodborne agents still awaits further studies, and its mode of transmission is largely unknown. The mechanisms of its pathogenicity and the production of virulence factors also need more researches and publications. This reviews focuses on the characteristics, the mode of transmission, the method of detection, and related foodborne disease and Symptoms, and prevention and control of the genus Arcobacter,contributing to knowledge in genus Arcobacterand the prevention of this emerging pathogen.
Key Words:Arcobacter, foodborne agents, emerging pathogen, human disease
The genus Arcobacterwas first defined in 1991 (Vandamme P. E.-1., 1991)from species of Campylobacter, and since then, several species have been classified into the genus, including Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowiiwhich lead to gastroenteric illness in humans. Arcobacter butzleri and Arcobacter cryaerophilushave been associated with human enteritis and bacteraemia(Kiehlbauch JA, 1991). In 2002, the international Commission on Microbiological Specificationsclassified A. butzleri as serious hazard that endangers human health (ICMSF, 2002).People infected with A. butzleri andA. skirrowii demonstrate diarrhea, nausea, and vomiting (Dediste A, 1998), but the reason and mechanism behind still remains unknown, as well as the infective dose. In addition, the species of Arcobactehave been found in animals with symptoms like gastrointestinal disorders and abortions, but also in animals without any symptoms. Due to the limitation in current technology, the incidence and dangerousnessof the genus Arcobactermight be underestimated (Vandenberg O, 2004). One of the reasons for the potential underestimation is that the optimal growth temperature for recovery of the genus Arcobacter is 30°C, while clinical specimens usually do not apply with this condition.
Contaminated water contributes to more than half of human infections of A. butzleri, and another important source of this genus is the consumption of poorly cooked products from animal origin.The genus Arcobacter have been isolated and recovered from food, especially in red meat such as pork and beef (L. Rivas, 2004). Foodborne illnesses resulting from A. butzlerihas become a public concern in recent years, and it has become one of the main project in food safety, raising concerns from both food industry and government.
The number of reported outbreaks of the genus Arcobacterremains unknown because currently it is not covered in any routine investsigation (Safty). However, frequent reports of the genus Arcobacter infection from cases of enteritis started to highlight the importance of study on this genus. Because the genus Arcobacter is considered to be a potential emergent enteropathogen agents of many disease, the study and research of the genus Arcobacter has become increasingly important in the last two decades. In recent years, numerous studies have been carried out and researches have made considerable progress in understanding the characteristics and pathogenicity of this bacterium.
Arcobacter spp.was first mentioned by Ellis et al. in 1977 as a taxon containing spirillum-like and gram-negative bacteria (Ellis, 1977). Together with Campylobacterand Helicobacter, the three genus consist the group rRNA superfamily VI Proteobacteria (Vandamme P. E., 1991). The nomenclature of genus Arcobacterwas revised multiple times from 1977 to 1992. It was at first classified as a member of Campylobacterdue to its ability to grow in a aerobically condition. Then, it was reclassified to a new genus Arcobacter.Unlike Campylobacter,the genus Arcobacter can growth within a wide range of temperature, ranging from 15 to 42°C. Another distinguishing feature is that members of this genus does not require hydrogen. In addition, members of it are micro-aerobic or aerobic (Vandamme P. E., 1991).
Then, other five bacteria have been added to the genus Arcobacter: A. butzleri, A. cryaerophilus, A. skirrowii, A. nitrofigilis, and A. sulfidicus(Vandamme P. M.)While two of them are harmless, the other three genus have been associated with human enteritis. A. cryaerophilushave been discovered in diarrhea patient (Kiehlbauch, 1991), and A. butzlerihas been isolated from patient with liver cirrhosis and in a patient with acute gangrenous appendicitis (Yan).The contribution of A. skirrowii isstill unknown.
Study of the genome of A. butzlerirevealed some virulence genes similar to those identified in Campylobacter and other bacteria, such as E. coliand Vibrio spp. already identified virulence-associated genes of A. butzleriinclude CiaB, which encodes Campylobacterinvasive antigen (CiaB), possibly contributing to invasion of the host cell. Study shows that virulence genes is frequently observed in beef-derived isolates, evidenced by the present of ciaB, mviN, and tlyAgenes (M. Tabatabaei, 2014). Although there are numerous studies on virulence factors, pathogenicity, and genetic diversity of Arcobacter, the characteristics of Arcobacter spp.is still in need of further study (L. Douidah, 2012).
Transmission and Detection
Currently, Arcobacteris not major hazard of the public health, but is regarded as an potential danger and emerging pathogen in human and a important factor regarding animal health. The genus Arcobacterare now considered as potential foodborne and waterborne pathogens (Gonzalez, 2007). In the transmission of this genus to animals or humans, water plays a important role, with the estimation that 63% of Arcobacter butzleriinfection from the consumption of contaminated water (Rice, 1999).Several reports of waterborne outbreaks are associated with the genus Arcobacterwaterborne outbreaks, including the outbreak in Slovenia (Kopilovic, 2008)and in Ohio (Fong, 2007).
Products from animals, including red meat, milk, and seafood, all have been evidenced to be contaminated with the genus Arcobacter (Collado, 2009).The genus Arcobacter is considered to be an emerging foodborne pathoen with increasing frequency of detection and and reporting. The consumption or handling of undercooked contaminated foods of animal origin and seafood are one of the major way of transmission of the genus Arcobacter. However, the epidemiology of Arcobacterin slaughterhouse infection is still unknown. Study showed that A. butzleriand A. cryaerophilusare frequently detected on slaughter equipment (K. Houf, 2013). Moreover, it is possible for the transmission of the genus Arcobacter to occur by contact with pets and other animals (Fera, 2008). The evidence is accumulating globally that livestock is one of the most significant reservoirs of the genus Arcobacter. People start to pay great attention to this genus due to its frequent detection in raw meat products. During a study conducted between 1998 and 1999, beef and pork from were used in a scientific research of the genus Arcobacter. The result turned out that the genus Arcobacterwere isolated from beef and pork is 2.2% and 7.0% respectively. The rate of isolations from beef is higher than that of pork (Kabeya, 2004).
The genusArcobacterisolates are found in food originated from animals and in water, and they are associated with human and animal diseases, as a result, rapid and specific identification of these species are demanded. To detect the genus Arcobacter, cultural detection is used frequently, and in the last few years, the refined isolation technique greatly improves the frequency of identification of the type the genus Arcobacter.In addition, with the improvement of technique such as PRC and other culturing techniques, non-cultural and cultural forms of the genus Arcobacterhave been detected. Moreover, the advance of DNA-based technique also help formulate quick and specific detection of the the genus Arcobacter (Lehner, 2005).
The genus Arcobacterare found in the digestive tract of healthy or unhealthy livestock animals with or without clinical signs of symptoms. In fecal samples from healthy cattle, pigs and and sheep, the presence of the genus Arcobacterhave been reported during the last two decades. The true occurrence of this potential pathogen agent in food is unknown due to lack of standard isolation method, which also reduces the comparability of field data from different studies (Lehner, 2005).
The common symptoms of Arcobacterinfection are diarrhoea with stomach cramps and abdominal pain (Lehner, 2005). The first human infection case of the genus was reported in 1988 (Vandamme P. E., 1991). A. butzleri has been isolated from bacteraemia, and the cases were associated with two patients with chronic disease, a neonatal patient and a liver cirrhosis patient. Infection has also been found in patient with uremic disease, suggesting that the underlying disease might contribute to the invasive infection of the genus Arcobacter (Hsuch et al., 1997). A study in 1996 shows that biotypes and serotypes of the Arcobacter detected in meat resembled those detected from human with diarrhoea (Marinescu et al. 1996). In an A. butzleri outbreak of 10 people infected in a Italian school, recurrent abdominal cramps without diarrhoea was the major symptoms, and there of them were hospitalized. The case indicated that it is possible for the genus to spread from person to person (Vandamme P. E., 1991).
Prevention and Control
To prevent the hazard of Arcobacter spp.in food, several studies have been conduct to assess the effectiveness of current treatment methods. The thermo tolerance of the genus in broth cultures are studied, with the result that for A. butzleriat 55°C , the decimal decline time was 0.4 min for cells in the stable growth phase and 1.1 min for cells in exponential growth phase. Cells in the stable phase stored in 4 °C environment will suffer a severe decline in number within 20 days (Lehner, 2005).
It is still unclear the relationship between the genus Arcobacterand human and animal disease. Human has great possibility to exposure themselves to this genus, thus it has been an increasing concern in terms of public health. Raw meat products such as pork and beef is a current focus of studies of the genus Arcobacter. The Epidemiologyof Arcobacterin human disease needs further examination, but some preparation and protection methods are desirable, which helps eradicate Arcobacterfrom the food chain of human. Its potential as foodborne agents, the mechanism of transmission, and pathogenic method still await more studies. Although the genus has not demonstrated any production of toxins and other virulence elements, it is obvious it has invasive and adhesive characteristics (Hoa T.K. Ho a, 2006).
To maintenance hygiene of slaughter is demanded, which is of great importance in meat product production process. One reason behind is that the carcasses contamination of the slaughter process largely result from unhealthy faecal carriage of livestock animals identified as foodborne pathogens. To reduce the pathogens agent risk, it is of great importance to maintenance keep the slaughter process hygiene and clean, which can be involved as a step in daily microbiological monitoring process. In addition, a standardized isolation process of the genus should be applied. Moreover, preventive measures should be promoted. For example, codes of health production practices should be designed and implemented, and relevant people need to put more care during the process of evisceration.
Arcobacterstrains demonstrate Antibiotic resistance with a significant level, but there it no technique is available to study the transformation of these strains and the construction of these mutants genetically. To better prevent and control the disease brought about by the genus Arcobacter, further studies should carried out to analyse the complete sequence of the genus Arcobactergenome. The prevalence of this genus in patients with diarrhoea and other symptoms needs to be studied, and virulence factors of the genus needs to be revealed. The epidemiology is still a filed demanding more publication and research.
In recent years, the occurrence of the genus Arcobacterinfection is increasing in number in food animals and food chain, raising concerns of the public. Since there is no standardized isolation methods for this genus, the low recovery of isolates might lead to an underestimation of the genus Arcobactertrue prevalence. Robust isolation and identification methods should be studied in order to evaluate the degree of risk exposure for human. Contaminated food products from livestock animals such as beef and pork will negatively affect human health. Efficient hygiene practices should be adopted in order to make foods free from the genus Arcobacter, which is a process need to encode in the whole food chain.
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