Foodborne and Waterborne Bacterial Pathogens: Epidemiology, Evolution and Molecular Biology
"a wealth of detailed, up-to-date information" (Microbiol. Today)
"an excellent foundation" (Clin. Inf. Dis.)
Caister Academic Press
Shah M. Faruque
Molecular Genetics Laboratory, International Centre for Diarrhoeal Disease Research, Bangladesh and Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
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Food- and waterborne pathogens continue to be a major cause of mortality in developing countries and cause significant morbidity in developed nations. Important pathogens include species or strains of Salmonella, Vibrio, Shigella, Escherichia coli, Yersinia, Staphylococcus and Campylobacter. Understanding the molecular basis of pathogenesis, its evolution and spread is critical to the development of new strategies for disease prevention and control. The application of genomic and other omics technologies in recent years has led to a deluge of information in this area, making it difficult for the busy researcher to keep abreast of developments. This timely book aims to capture the essence of the latest developments to provide a timely overview of the field. Written by leading bacteriologists, chapters cover all the important bacteria and review topics such as pathogenic properties, population genetics, virulence genes, evolution, drug resistance, epidemiology, detection, identification and control strategies. Other topics include the molecular basis for enhanced transmissibility of waterborne pathogens, their mode of survival in the environment, and the evolution of new species with increased fitness both as pathogens and environmental organisms. Essential reading for microbiologists working with these and related pathogens.
"there is a wealth of detailed, up-to-date information on the epidemiology, pathogenesis and molecular biology of these pathogens written by experts in the field. This book would very useful to those studying gastrointestinal bacterial pathogens or food and water microbiology at postgraduate level and as a reference for specialists working in this area." from Microbiology Today (2013)
"this book addresses important themes in the molecular epidemiology of bacterial pathogens ... Another consistent strength of this book is the detailed coverage of antibiotic resistance across the entire spectrum of food and waterborne pathogens ... for clinicians, food or environmental scientists, or public health officials interested in gaining a foundation in the molecular microbiology of this important group of pathogens, this book would provide an excellent foundation. Alternatively, for those with expertise in specific organisms, this book provides an interesting look across the spectrum of food and waterborne bacterial pathogens." from Clin. Inf. Dis. (2013)
Table of contents
Shah M. Faruque
Foodborne and waterborne bacterial pathogens are a major cause of mortality in developing countries and cause significant morbidity in developed nations. Some countries carry a disproportionately heavy burden of these infectious diseases due to inadequate resources to provide sanitation and hygienic facilities, and safe water. The most important bacterial pathogens transmitted through contaminated water and food include species or strains of Salmonellae, Vibrio (e.g., V. cholerae, V. parahemolyticus, V. vulnificus); Shigella (S. dysnteriae, S. flexneri, S. sonnie, S. boydii); Escherichia coli, Yersinia, Staphylococcus and Campylobacter. The pathogenic mechanisms of these bacteria involve synergistic actions of multiple virulence factors produced by the pathogen after infecting the host. Besides carrying sets of virulence genes which are often horizontally transferred between strains, many of these bacteria may also carry precise genetic programs that allow them to adapt and survive in water leading to enhanced transmission or prolonged persistence in the aquatic environment. Understanding the epidemiology, pathogenesis and evolution of these pathogens can contribute significantly to control foodborne and waterborne diseases.
2 . Epidemiology, Pathogenesis and Genetics of Diarrhoeagenic Escherichia coli Infections
T. Ramamurthy and M. John Albert
There are five categories of diarrhoeagenic Escherichia coli (DEC) namely enterotoxigenic, enteropathogenic, enterohaemorrhagic, enteroinvasive and enteroaggregative. They have evolved from nonpathogenic commensal strains by acquisition of specific virulence genes through mobile genetic elements. Their pathogenesis differs and they produce distinct clinical syndromes and pathological lesions and have different epidemiological characteristics. The virulence genes are carried on plasmids, bacteriophages, transposons or pathogenicity islands. DEC produce an array of virulence factors which include colonization factors, enterotoxins, cytotoxins, haemolysins, invasins etc. The diseases they produce range from acute watery diarrhea to dysentery to bloody diarrhoea with haemolytic uraemic syndrome. Even though the major burden of the disease is in the developing world, no part of the world is free from them, and EHEC infections are predominant in developed countries. A variety of molecular tools have been developed to study the diversity and transmission of these pathogens. Even though attempts are being made, no ideal vaccine exists against any category of DEC, therefore maintaining appropriate food and water hygiene are the only ways to keep the infections under control. We must also be on guard against the emergence of new pathogenic strains. The recent emergence of a hybrid enteroaggregative-haemorrhagic E. coli with the rare serotype of O104:H4 in Germany that caused high mortality rates is a case in point.
3. Population Genetics and Molecular Epidemiology of Shigella species
Kaisar Ali Talukder and Ishrat Jahan Azmi
Shigellosis, also known as acute bacillary dysentery, produces inflammatory reactions and ulceration on the intestinal epithelium followed by bloody or mucoid diarrhoea. Shigellosis is caused by any one of the four species or groups of Shigella, namely, S. dysenteriae, S. flexneri, S. boydii, and S. sonnei. At least 54 serotypes or subtypes of Shigella are currently recognized, of which S. dysenteriae has 16 serotypes, S. flexneri has 17 serotypes and subserotypes, S. boydii has 20 and S. sonnei has a single serotype. Shigellosis can occur in sporadic, epidemic and pandemic forms. To develop an effective vaccine it is important to monitor the prevalent serotypes and their changes around the world because immunity to Shigella is serotype specific. The genetic variability between serotypes and emergence of atypical strains accentuates the problems to the development of an effective vaccine. In view of the emergence of new strains with altered characteristics than the ones established globally for many years, there is also a need for revising the nomenclature for the three groups of Shigella: flexneri, boydii and dysenteriae. This chapter discusses the recent serotyping scheme of Shigella with special focus on the emergence of new variants and the necessity to make an updated scheme. Furthermore, the epidemiology, phenotypic and molecular characteristics, population genetics and clinical impact of these variants have been described.
4. Molecular Pathogenesis, Epidemiology and Drug Resistance of Shigella species
G. P. Pazhani and T. Ramamurthy
Shigella species are often associated with diarrhoea/dysentery among children in developing countries of Asia-African regions and also cause foodborne infections in developed countries. During infection, this pathogen secretes a number of effectors via the type III secretion system. Recently, Shigella-infected cases have increased considerably in Asia, but the death rate decreased substantially due to nutritional and clinical interventions. Antimicrobials reduce the episodes of shigellosis. However, multiple antibiotic resistance in shigellae have increased over the years due to improper use of antimicrobials in the treatment of diarrhoea. Several mechanisms such as plasmids and other mobile genetic elements are involved in the transmission of resistance in shigellae. Due to poor efficacy of many of the existing Shigella vaccines, none has been licensed for use in endemic areas. This chapter reviews our current understanding of mechanism involved in the pathogenesis of Shigella, antimicrobial resistance and also its epidemiological importance and clinical management of shigellosis.
5. Salmonellae: Taxonomy, Genomics and Antimicrobial Resistance
The genus Salmonella has three species namely Salmonella enterica, Salmonella bongori and Salmonella subterranean. The type species S. enterica is further classified into six subspecies: enterica (subsp. I), arizonae (subsp. IIIa), diarizonae (subsp. IIIb), houtenae (subsp. IV), indica (subsp. VI), and salamae (subsp. II). Salmonella strains belong to over 50 serogroups based on the O antigen, and to over 2500 serovars (each having a unique combination of somatic O, flagellar H1 and H2 antigens). Most of these serovars (1,531) belong to Salmonella subsp., enterica, and cause more than 99% of the diseases in humans including gastroenteritis and enteric fever (typhoid). Genome sequencing and comparative genomic analysis of 28 S. enterica serovars identified similarity of core regions of the genomes, together with evidence of recombination and rearrangement, genomic degradation, pseudogenes and clonal diversity both within and among the serovars. Genomic comparisons of host-restricted (S. Typhi, S. Paratyphi and S. Gallinarum) and host-adapted (S. Typhimurium and S. Enteridis) S. enterica serovars indicate that genomic degradation is a common evolutionary mechanism for host adaptation and increased pathogenicity of Salmonella. Drug resistances in Salmonella is mainly due to Salmonella genomic island 1 (an integrative mobile element) carrying various antibiotic resistance gene clusters, and to conjugative R plasmids which confer resistance to many antibiotics including extended-spectrum cephalosporins. Continuous genetic re-assortment in Salmonella leading to increased virulence and the emergence of resistance to multiple drugs are of significant public health concern.
6. Molecular Aspects of Pathogenesis and Drug Resistance in Salmonella Species
Indrani Karunasagar, Patit Paban Bhowmick and Deekshit Vijaya Kumar
Foodborne and waterborne infections due to Salmonella species are a major concern worldwide. Several virulence genes have been identified in Salmonella and located in clusters called Salmonella Pathogenicity Island (SPI). There are 17 Pathogenicity Islands of Salmonella reported to date. Salmonella possess two distinct type three secretion system (T3SS) encoded by genes present in two different SPI viz. SPI-1 and SPI-2 that play an important role in adhesion, invasion and survival in the host cells. It has been also reported that a variety of Salmonella phenotypes associated with bioluminescence, biofilm formation, conjugation, motility, competence, and antibiotic production, are regulated in response to signaling molecules of quorum-sensing systems. The development of resistance to various antibiotics (particularly in Asian countries) including extended-spectrum cephalosporins worldwide is a cause of concern. Some variants of Salmonella have developed multidrug-resistance as an integral part of the genetic material of the organism, and are therefore likely to retain their drug-resistance genes even when antimicrobial drugs are no longer used. The role of plasmids, bacteriophages, transposons and integrons in the transfer of resistance genes is discussed.
7. Epidemiology, Molecular Biology and Detection of Foodborne Vibrio parahaemolyticus infections
Marie Yeung and Kathryn J. Boor
As a natural inhabitant of the marine environment, Vibrio parahaemolyticus is frequently present in seafood, and particularly in oysters. V. parahaemolyticus can multiply rapidly under favorable conditions, but also may exist in a viable but non-culturable state under unfavorable conditions. A small subset of this species can cause human disease, with acute gastroenteritis as the predominant clinical manifestation. Two pore-forming hemolysins, thermostable direct hemolysin (TDH) and TDH-related hemolysin (TRH), are recognized as contributors to V. parahaemolyticus pathogenesis. Therefore, many detection methods for pathogenic strains focus on determining the presence of the genes encoding these hemolysins or on detection of beta-hemolysis on Wagatsuma agar (i.e. the Kanagawa Phenomenon). Serotyping and molecular fingerprinting techniques are also used to subtype Vibrio parahaemolyticus isolates. One of the most effective strategies for preventing Vibrio parahaemolyticus infection from consumption of raw or uncooked seafood is to reduce seafood post-harvest storage temperatures to prevent the growth of this species.
8. Epidemiology and Genetics of the Pandemic Clone of Vibrio parahaemoluyicus
Indrani Karunasagar, Krishna Kumar and G. Balakrish Nair
Members of the Vibrionaceae family occurring in marine environment are responsible for many of the reported cases of infection worldwide. Among these, Vibrio parahaemolyticus is an important food-borne pathogen transmitted through contaminated seafood. Historically, food poisoning due to V. parahaemolyticus occurred as sporadic cases caused by different serotypes without the clustering of one particular serotype. With the emergence of the pandemic clone belonging to O3:K6 serotype in Kolkata, India, in 1996, the epidemiology of this organism changed abruptly causing large outbreaks and rapid hospitalizations. This new highly virulent strain is now globally disseminated. This chapter traces the epidemiology of the pandemic strain of V. parahaemolyticus, its emergence, molecular characteristics and clonal dissemination.
9. Epidemiology and Molecular Pathogenesis of Vibrio vulnificus
Iddya Karunasagar and Anusha Rohit
Vibrio vulnificus is a normal inhabitant of warm estuarine environments all over the world and may be associated with a wide variety of seafood. In susceptible individuals with underlying liver disease, diabetes or other immunocompromised condition and consuming raw seafood, the organism can cause primary septicaemia with a mortality rate of over 50%. A number of putative virulence factors such as capsule, cytotoxic factors, iron acquisition factors and factors responsible for evading the immune system of the host have been described and multiple factors seem to be involved in causing disease symptoms. The organism can be isolated, identified and enumerated by traditional microbiological methods as well as molecular methods such as polymerase chain reaction (PCR) and real time PCR. Clinical strains can be generally distinguished from most environmental strains by genetic fingerprinting techniques. The organism does not grow at temperatures below 13°C and therefore an important control measure is to cool the seafood to temperatures below this within a few hours of harvest. The organism is sensitive to mild heat, which can be used as a postharvest treatment method to minimise the risk of infection. Relaying shellfish to waters with salinity of >30 ppt has also been found to be an important control measure.
10. Epidemiology and Molecular Biology of Vibrio cholerae
Shah M. Faruque and John J. Mekalanos
Vibrio cholerae belonging to O1 and O139 seropgroups cause cholera, a life-threatening diarrhoeal disease, which spreads through consumption of water and food contaminated with the pathogen. Other serogroups of V. cholerae are also occasionally associated with mild to moderate enteric infections. Although V. cholerae is a human pathogen, the bacteria are part of the normal aquatic flora in estuarine and brackish waters, and thus are able to persist in the environment outside the human host. The ability of V. cholerae strains to cause disease in humans depends on their virulence gene content, which varies between pathogenic and nonpathogenic strains. Horizontal transfer of critical virulence genes among different V. cholerae strains, as well as microevolution of bacterial genes contribute significantly to the emergence of V. cholerae strains with altered antigenic and pathobiological properties. Seasonal cholera epidemics may selectively enrich genetic variants with unique properties that promote transmission or environmental persistence. The ecosystem comprising V. cholerae, the aquatic environment and the human host offers an understanding of the complex relationship between pathogenesis and the evolution of a typical waterborne bacterial pathogen.
11. Biology of Campylobacter Infection
Lieneke I. Bouwman and Jos P.M. van Putten
Campylobacter species are one of the leading causes of bacterial foodborne disease. Campylobacter survives and flourishes in a variety of environmental niches but causes pathology mainly in humans. The pathogenesis of the disease is still poorly understood, and currently only a few Campylobacter virulence determinants have been proposed. Recent studies indicate that Campylobacter displays extensive genome plasticity and a range of environmental adaptation, that likely contribute to the success of the pathogen. In this chapter, we will discuss the state-of-the-art of the epidemiology, molecular biology, and pathogenesis of Campylobacter infection.
12. Epidemiology, Pathogenesis, Ecology and Genetics of Listeria monocytogenes
Sangmi Lee, Robin M. Siletzky and Sophia Kathariou
Listeria monocytogenes is a Gram-positive foodborne pathogen that causes a severe, potentially fatal illness (listeriosis) in animals and humans. The only human pathogen within the genus Listeria, this bacterium is equipped with sophisticated mechanisms to invade mammalian cells and proliferate inracellularly. Population genetics data indicate that some groups of L. monocytogenes are more frequently associated with human listeriosis. However, the ecology and potentially unique characteristics of such groups remain to be elucidated. This chapter discusses recent advances in the epidemiology of listeriosis and epidemic-associated clonal groups; the characterization of pathogenicity of L. monocytogenes; the evolution of Listeria species and L. monocytogenes; and the increasingly recognized importance of Listeria phages in the ecology of L. monocytogenes in food processing facilities.
13. Epidemiology, Virulence Genes, and Reservoirs of Enteropathogenic Yersinia species
Riikka Laukkanen-Ninios and Maria Fredriksson-Ahomaa
Enteropathogenic yersiniosis is caused due to foodborne infection with Yersinia enterocolitica and Y. pseudotuberculosis. Several virulence factors have been identified that are common to these two pathogens even though Y. pseudotuberculosis is genetically more related to Y. pestis, which is typically transmitted by fleas and not through foods. Diarrhoea and abdominal pain are the most dominant symptoms for Y. enterocolitica and Y. pseudotuberculosis infections. Occasionally, complications such as joint pain and skin rash may occur, typically among adults. Most human cases are caused by Y. enterocolitica. The reported cases are mainly sporadic and outbreaks are uncommon. However, outbreaks of Y. pseudotuberculosis infection, often in school children, have occurred in Finland, Russia and Japan. The most important transmission route is proposed to be via contaminated foods even though these pathogens have seldom been isolated from foods. The low isolation rates are probably due to the low sensitivity of the culture methods. Y. enterocolitica infections have been linked to raw or under-cooked pork and pork products while Y. pseudotuberculosis infections have been linked to raw fresh produce and surface water. Pigs are so far the most important reservoir for human pathogenic Y. enterocolitica. The principal reservoir of Y. pseudotuberculosis is believed to be wild animals, especially rodents and birds. Transmission routes of these pathogens from animals to humans are mostly unknown.
14. Bacterial Factors Encoded by Mobile and Integrative Genetic Elements in Enteric Pathogens
E. Fidelma Boyd
The acquisition of new phenotypes by bacteria is largely driven by horizontal gene transfer (HGT), a process that is ubiquitous among bacteria and universally present among enteric pathogens. The common vectors of HGT in enteric pathogens include phages, pathogenicity islands and plasmids, all genetic elements that can encode virulence factors essential for host colonization and infection. In this review, Salmonella enterica, Escherichia coli, Vibrio cholerae and V. parahaemolyticus are discussed in terms of their virulence genes encoded within mobile and integrative genetic elements and their role in the mechanism of pathogenesis.
15. Conclusion and Future Prospect
Shah M. Faruque
Recent studies have provided remarkable insights to our general understanding of the epidemiology, genetics, and ecology of foodborne and waterborne bacterial pathogens. Some of these bacteria have recently been reclassified with updated nomenclature; identification methods have also improved substantially with more extensive use of molecular approaches. The bulk of information generated in different areas of research in these pathogenic organisms have been summarized to provide an over all impression of the progress made. Future directions for research into these organisms have also been discussed with a view to understanding general themes of bacterial pathogens, that cause foodborne and waterborne diseases. In addition, available preventive measures to reduce incidences of disease due to these organisms have been discussed.
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(EAN: 9781908230065 9781912530397 Subjects: [microbiology] [bacteriology] [medical microbiology] [molecular microbiology] [environmental microbiology] )