- Email: [email protected]
To the guts of spirochaete biology
BOOK
REVIEWS
of the book, considering most of the articles are in review format and are both thorough and packed with further references. What of the weaknesses of the book? First, I would have liked to have seen more discussion of the new variant of Creutzfeldt-Jakob disease (CJD), which has been associated with bovine spongiform encephalopathy (BSE). The chapter on human disorders is remarkably reticent about the evidence linking the two, which was published last year, and the new variant CJD pathology is not treated particularly thoroughly. Similarly, although the book steers clear of controversy and speculation, which is sensible in view of the anxieties (if not panic) that were stirred up when the UK epidemic of BSE first hit the headlines, I found it had little time for alternative views. Hence, it dismisses the evidence for a separate infor-
To the guts of spirochaete biology Intestinal Spirochaetes in Domestic Animals and Humans edited by D.J. Hampson and T.B. Stanton CAB International, 1996. £60.00 hbk (ix + 382 pages) ISBN 0 85199 140 8
p
athogenic spirochaetes belonging to what we now know constitute several different genera were first described in the early part of this century. However, knowledge of the biology of spirochaetes has lagged well behind that of other bacteria because many spirochaetes proved initially to be either uncultivatable or very difficult to culture, especially in the quantities required for normal physico-chemical characterization. For example, the precise structure of lipopolysaccharide (LPS) has not yet been elucidated in any spirochaete. More recently, rapid advances in the understanding of pathogenesis in other bacteria have been brought about by the application of molecular biology techniques that have not previously been available for spirochaetes. Indeed, the first transformation and allelic exchange for any spirochaete
TRENDS
mational nucleic acid in the prion agent without giving space for the available evidence. Although there is no consistent evidence regarding either nucleic acid involvement or conventional viral agents, some discussion of these factors would have been helpful, and a separate chapter dealing with the nature of the agent would have been useful for the interested nonexpert. In addition, the book more or less ignores the large body of data indicating the striking similarities between transmission and the classical infective process. I presume this is to aid clarity of purpose, but the data are both fascinating and relevant. The extreme interest in these illnesses makes this book relevant, as the cover says, to neuroscientists, veterinary scientists and clinicians, as well as policymakers. However, as the style is mainly in the form of scientific reviews, it would be a very
dedicated policymaker who would be willing and able to come to grips with the intricacies of transgenic mouse experiments. Similarly, much of the descriptions would be difficult to understand by the nonmolecular veterinary scientist or clinician. Nevertheless, the authors and editors give a very readable and concise treatment of a subject that is riddled with phenomena that challenge logic and presuppositions. For the reader with some molecular background, this represents an invaluable resource and, for the reader without, it provides a worthwhile challenge. The concise nature of the book introduces a bias towards the prion protein itself but, overall, it accurately reflects the current tide of opinion.
was only reported in 1992. Nevertheless, the advent of molecular biology has greatly expanded our knowledge of spirochaete biology in the past 10 years. Thus, the publication of this book is very timely. It would have been very straightforward to produce a book of this type that would be of interest or value to only a rather restricted range of readers. That is not the case here. The editors have not only assembled an impressive array of expertise to produce a superb and current compendium of information on intestinal spirochaetes, but they have also produced a book that is relevant to researchers of other spirochaetes. As spirochaetes diverged early in evolution and form a comparatively closely related phylogenetic grouping, much of the information presented and the investigative approaches used for intestinal spirochaetes are also applicable to other spirochaetes. Furthermore, most of the authors, especially those in Part I ('Characteristics of intestinal spirochaetes'), have adopted a comparative approach in which intestinal spirochaetes are considered along with other spirochaete genera. It is pleasing to see that the authors have interpreted the chapter headings quite broadly. For exam-
ple, Chapter 5 on the ultrastructure of intestinal spirochaetes includes detailed and current information on the molecular analysis of LPS, flagellar proteins and membrane lipoproteins. The same is true of Chapter 3, where the genetic organization of the principle spirochaete genera is compared, and Chapter 4, which details the molecular biology of Serpulina hyodysenteriae. There is, therefore, some overlap and repetition between chapters. However, this enhances rather than detracts from the book because it facilitates the finding of information. In contrast, Chapter 6, which is devoted to virulence factors, is understandably rather sparse because our understanding of the molecular pathogenesis of intestinal spirochaetes is still in its infancy; doubtless, this will increase rapidly in the next few years as genetic exchange systems become available. Intestinal Spirochaetes in Domestic Animals and Humans will also be of value to non-spirochaete microbiologists because it provides information that is not readily accessible elsewhere. As a spirochaete researcher, I am often contacted by colleagues outside the field requesting more up-to-date information than is available in the textbooks. At least in the case of intestinal
IN MICROBIOLO(3Y
376
VOL.
5
NO.
Steve Whatley Dept of Neuroscience, Institute of Psychiatry, London, UK SE5 8AF
9
SEPTEMBER
1997
BOOK
REVIEWS
spirochaetes, I will now have somewhere to refer them to. Part II ('Diseases associated with intestinal spirochaetes') is likely to be of more interest than Part I to veterinarians, veterinary pathologists and veterinary microbiologists because it focuses more specifically on intestinal spirochaete diseases in swine, avian species and companion animals. Coupled with the information presented in Part III ('Diagnosis and control of intestinal
spirochaetes'), this section is generally of sufficient detail to serve as a manual for diagnosis and treatment, without the need to look elsewhere. Chapter 9 ('Human intestinal spirochaetosis') summarizes current knowledge of the association of intestinal spirochaetes with disease in humans, a somewhat controversial area in which much more information clearly needs to be obtained. In summary, the editors and authors have succeeded in produc-
ing a major reference work of relevance for all spirochaetologists (for whom it is a must), other microbiologists (both research and diagnostic) and veterinarians and veterinary workers. I commend them on their efforts.
The E. coil options guide
enterotoxigenic strains, the plasmid-encoded type IV fimbriae and pathogenicity island-encoded type III secretion system package is found in enteropathogenic strains, and packages containing pathogenicity islands encoding P fimbriae and hemolysin can be found in pyelonephritogenic strains. Combinations of packages are also possible; for example, enterohemorrhagic strains are defined by a combination of the phage-encoded Shiga toxins and the pathogenicity island from enteropathogenic E. coll. With all the available E. coil variations, there is a pressing need for a detailed 'options' guide. Indeed, so much has been learned about each category of pathogenic E. coli that it is difficult to do justice to more than one pathotype in a review article. Thus, the arrival of Escher-
mary is somewhat outdated, omitting many of the exciting late developments that have advanced our understanding of the pathogenesis of E. coli infections and including concepts that are no longer helpful in light of recent progress. The subsequent chapters vary in content, timeliness and importance: those on lipopolysaccharide, hemolysins and adhesive fimbriae are particularly fine, but others are out of date, incomplete or dull. In addition, there is a certain redundancy, as virulence factors are mentioned in the introductory chapters, detailed in part two, and reiterated in the section on particular pathotypes. This will not trouble those using the book as a reference, but will be tedious for those choosing to read the entire text. In conclusion, this volume will be most valuable as a reference book, complementing, for example, the excellent, but less disease-oriented, book Escherichia coli and Salmonella 1. Those wishing to have information on a variety of mechanisms of E. coli pathogenesis at hand will probably want to own this book, but those looking for the most up-to-date perspectives on pathogenesis by a particular type of E. coli may be better off referring to recent review articles.
Escherichia coli: Mechanisms of Virulence
edited by M. Sussman Cambridge University Press, 1997. £65.00 hbk (xvi + 639 pages) ISBN 0 521 45361 5
E
scherichia coli may be the
most versatile of human pathogens. Not only is it the dominant Gram-negative facultarive anaerobe in the human gastrointestinal tract, but it is also a potent pathogen capable of causing a variety of diseases by an array of mechanisms. E. coli can cause no less than six clinical syndromes of diarrhea with overlapping, but distinct, symptoms and epidemiology: urinary tract infections ranging from asymptomatic bacteriuria to urosepsis; neonatal meningitis; pneumonia; cholecystitis; and wound infections. How can one species account for so many diseases? The answer may be that E. coli is the consummate genetic scavenger. The various clinical syndromes ascribed to E. coli are caused by strains that differ from each other because they have acquired distinct sets of specific virulence genes. These genes are carried on plasmids, lysogenic bacteriophages or large chromosomal insertions known as pathogenicity islands. My colleague, Harry Mobley, has likened the genetic variability of E. coli to the options available to the prospective new car buyer. In addition to the basic, stripped-down model, represented by the venerable K-12 strain, a variety of available 'options packages' exist. For example, colonization factor antigen and toxin packages are found in
TRENDS IN
ichia coli: Mechanisms of Virulence is most welcome. The text, contributed by accomplished experts in the appropriate field, is organized into four sections: an introduction containing overviews of human and animal infections and colonization, a section on individual virulence factors, a section on five different pathotypes of E. coli, and a section on response to infection. The coverage is fairly good, although chapters on the enterotoxigenic, aggregative and diffuse-adherent categories of diarrheagenic E. coli, as well as a chapter on strains that cause neonatal meningitis, are conspicuously absent. The book begins somewhat inauspiciously with a lengthy introductory chapter by the Editor, which, rather than identifying unifying themes or providing a wise perspective, merely presages what is to follow. Furthermore, this sum-
MICR()BIOL()GY
377
Ben Adler
Dept of Microbiology, Monash University, Clayton, VIC 3168, Australia
Michael S. Donnenberg
Divn of Infectious Diseases, University of Maryland School of Medicine, 10 S. Pine Street, MSTF 900, Baltimore, MD 21201, USA References
1 Neidhardt,F.C.et al., eds (1996) Escherichiacoliand Salmonella,ASM Press
VOL. 5 NO. 9 SEPTEMBER 1 9 9 7
REVIEWS
of the book, considering most of the articles are in review format and are both thorough and packed with further references. What of the weaknesses of the book? First, I would have liked to have seen more discussion of the new variant of Creutzfeldt-Jakob disease (CJD), which has been associated with bovine spongiform encephalopathy (BSE). The chapter on human disorders is remarkably reticent about the evidence linking the two, which was published last year, and the new variant CJD pathology is not treated particularly thoroughly. Similarly, although the book steers clear of controversy and speculation, which is sensible in view of the anxieties (if not panic) that were stirred up when the UK epidemic of BSE first hit the headlines, I found it had little time for alternative views. Hence, it dismisses the evidence for a separate infor-
To the guts of spirochaete biology Intestinal Spirochaetes in Domestic Animals and Humans edited by D.J. Hampson and T.B. Stanton CAB International, 1996. £60.00 hbk (ix + 382 pages) ISBN 0 85199 140 8
p
athogenic spirochaetes belonging to what we now know constitute several different genera were first described in the early part of this century. However, knowledge of the biology of spirochaetes has lagged well behind that of other bacteria because many spirochaetes proved initially to be either uncultivatable or very difficult to culture, especially in the quantities required for normal physico-chemical characterization. For example, the precise structure of lipopolysaccharide (LPS) has not yet been elucidated in any spirochaete. More recently, rapid advances in the understanding of pathogenesis in other bacteria have been brought about by the application of molecular biology techniques that have not previously been available for spirochaetes. Indeed, the first transformation and allelic exchange for any spirochaete
TRENDS
mational nucleic acid in the prion agent without giving space for the available evidence. Although there is no consistent evidence regarding either nucleic acid involvement or conventional viral agents, some discussion of these factors would have been helpful, and a separate chapter dealing with the nature of the agent would have been useful for the interested nonexpert. In addition, the book more or less ignores the large body of data indicating the striking similarities between transmission and the classical infective process. I presume this is to aid clarity of purpose, but the data are both fascinating and relevant. The extreme interest in these illnesses makes this book relevant, as the cover says, to neuroscientists, veterinary scientists and clinicians, as well as policymakers. However, as the style is mainly in the form of scientific reviews, it would be a very
dedicated policymaker who would be willing and able to come to grips with the intricacies of transgenic mouse experiments. Similarly, much of the descriptions would be difficult to understand by the nonmolecular veterinary scientist or clinician. Nevertheless, the authors and editors give a very readable and concise treatment of a subject that is riddled with phenomena that challenge logic and presuppositions. For the reader with some molecular background, this represents an invaluable resource and, for the reader without, it provides a worthwhile challenge. The concise nature of the book introduces a bias towards the prion protein itself but, overall, it accurately reflects the current tide of opinion.
was only reported in 1992. Nevertheless, the advent of molecular biology has greatly expanded our knowledge of spirochaete biology in the past 10 years. Thus, the publication of this book is very timely. It would have been very straightforward to produce a book of this type that would be of interest or value to only a rather restricted range of readers. That is not the case here. The editors have not only assembled an impressive array of expertise to produce a superb and current compendium of information on intestinal spirochaetes, but they have also produced a book that is relevant to researchers of other spirochaetes. As spirochaetes diverged early in evolution and form a comparatively closely related phylogenetic grouping, much of the information presented and the investigative approaches used for intestinal spirochaetes are also applicable to other spirochaetes. Furthermore, most of the authors, especially those in Part I ('Characteristics of intestinal spirochaetes'), have adopted a comparative approach in which intestinal spirochaetes are considered along with other spirochaete genera. It is pleasing to see that the authors have interpreted the chapter headings quite broadly. For exam-
ple, Chapter 5 on the ultrastructure of intestinal spirochaetes includes detailed and current information on the molecular analysis of LPS, flagellar proteins and membrane lipoproteins. The same is true of Chapter 3, where the genetic organization of the principle spirochaete genera is compared, and Chapter 4, which details the molecular biology of Serpulina hyodysenteriae. There is, therefore, some overlap and repetition between chapters. However, this enhances rather than detracts from the book because it facilitates the finding of information. In contrast, Chapter 6, which is devoted to virulence factors, is understandably rather sparse because our understanding of the molecular pathogenesis of intestinal spirochaetes is still in its infancy; doubtless, this will increase rapidly in the next few years as genetic exchange systems become available. Intestinal Spirochaetes in Domestic Animals and Humans will also be of value to non-spirochaete microbiologists because it provides information that is not readily accessible elsewhere. As a spirochaete researcher, I am often contacted by colleagues outside the field requesting more up-to-date information than is available in the textbooks. At least in the case of intestinal
IN MICROBIOLO(3Y
376
VOL.
5
NO.
Steve Whatley Dept of Neuroscience, Institute of Psychiatry, London, UK SE5 8AF
9
SEPTEMBER
1997
BOOK
REVIEWS
spirochaetes, I will now have somewhere to refer them to. Part II ('Diseases associated with intestinal spirochaetes') is likely to be of more interest than Part I to veterinarians, veterinary pathologists and veterinary microbiologists because it focuses more specifically on intestinal spirochaete diseases in swine, avian species and companion animals. Coupled with the information presented in Part III ('Diagnosis and control of intestinal
spirochaetes'), this section is generally of sufficient detail to serve as a manual for diagnosis and treatment, without the need to look elsewhere. Chapter 9 ('Human intestinal spirochaetosis') summarizes current knowledge of the association of intestinal spirochaetes with disease in humans, a somewhat controversial area in which much more information clearly needs to be obtained. In summary, the editors and authors have succeeded in produc-
ing a major reference work of relevance for all spirochaetologists (for whom it is a must), other microbiologists (both research and diagnostic) and veterinarians and veterinary workers. I commend them on their efforts.
The E. coil options guide
enterotoxigenic strains, the plasmid-encoded type IV fimbriae and pathogenicity island-encoded type III secretion system package is found in enteropathogenic strains, and packages containing pathogenicity islands encoding P fimbriae and hemolysin can be found in pyelonephritogenic strains. Combinations of packages are also possible; for example, enterohemorrhagic strains are defined by a combination of the phage-encoded Shiga toxins and the pathogenicity island from enteropathogenic E. coll. With all the available E. coil variations, there is a pressing need for a detailed 'options' guide. Indeed, so much has been learned about each category of pathogenic E. coli that it is difficult to do justice to more than one pathotype in a review article. Thus, the arrival of Escher-
mary is somewhat outdated, omitting many of the exciting late developments that have advanced our understanding of the pathogenesis of E. coli infections and including concepts that are no longer helpful in light of recent progress. The subsequent chapters vary in content, timeliness and importance: those on lipopolysaccharide, hemolysins and adhesive fimbriae are particularly fine, but others are out of date, incomplete or dull. In addition, there is a certain redundancy, as virulence factors are mentioned in the introductory chapters, detailed in part two, and reiterated in the section on particular pathotypes. This will not trouble those using the book as a reference, but will be tedious for those choosing to read the entire text. In conclusion, this volume will be most valuable as a reference book, complementing, for example, the excellent, but less disease-oriented, book Escherichia coli and Salmonella 1. Those wishing to have information on a variety of mechanisms of E. coli pathogenesis at hand will probably want to own this book, but those looking for the most up-to-date perspectives on pathogenesis by a particular type of E. coli may be better off referring to recent review articles.
Escherichia coli: Mechanisms of Virulence
edited by M. Sussman Cambridge University Press, 1997. £65.00 hbk (xvi + 639 pages) ISBN 0 521 45361 5
E
scherichia coli may be the
most versatile of human pathogens. Not only is it the dominant Gram-negative facultarive anaerobe in the human gastrointestinal tract, but it is also a potent pathogen capable of causing a variety of diseases by an array of mechanisms. E. coli can cause no less than six clinical syndromes of diarrhea with overlapping, but distinct, symptoms and epidemiology: urinary tract infections ranging from asymptomatic bacteriuria to urosepsis; neonatal meningitis; pneumonia; cholecystitis; and wound infections. How can one species account for so many diseases? The answer may be that E. coli is the consummate genetic scavenger. The various clinical syndromes ascribed to E. coli are caused by strains that differ from each other because they have acquired distinct sets of specific virulence genes. These genes are carried on plasmids, lysogenic bacteriophages or large chromosomal insertions known as pathogenicity islands. My colleague, Harry Mobley, has likened the genetic variability of E. coli to the options available to the prospective new car buyer. In addition to the basic, stripped-down model, represented by the venerable K-12 strain, a variety of available 'options packages' exist. For example, colonization factor antigen and toxin packages are found in
TRENDS IN
ichia coli: Mechanisms of Virulence is most welcome. The text, contributed by accomplished experts in the appropriate field, is organized into four sections: an introduction containing overviews of human and animal infections and colonization, a section on individual virulence factors, a section on five different pathotypes of E. coli, and a section on response to infection. The coverage is fairly good, although chapters on the enterotoxigenic, aggregative and diffuse-adherent categories of diarrheagenic E. coli, as well as a chapter on strains that cause neonatal meningitis, are conspicuously absent. The book begins somewhat inauspiciously with a lengthy introductory chapter by the Editor, which, rather than identifying unifying themes or providing a wise perspective, merely presages what is to follow. Furthermore, this sum-
MICR()BIOL()GY
377
Ben Adler
Dept of Microbiology, Monash University, Clayton, VIC 3168, Australia
Michael S. Donnenberg
Divn of Infectious Diseases, University of Maryland School of Medicine, 10 S. Pine Street, MSTF 900, Baltimore, MD 21201, USA References
1 Neidhardt,F.C.et al., eds (1996) Escherichiacoliand Salmonella,ASM Press
VOL. 5 NO. 9 SEPTEMBER 1 9 9 7