663
© Springer International Publishing Switzerland 2016
B. Austin, D.A. Austin, Bacterial Fish Pathogens,
DOI 10.1007/978-3-319-32674-0_13
Chapter 13
Diagnosis
Abstract Historically, scientists have seemed loath to make rapid diagnoses, preferring to adopt laborious testing regimes. Yet, diagnostic techniques have their
drawbacks insofar as it is not always certain that the actual pathogen is recognized.
Culture-dependent methods may highlight secondary invader or contaminants.
Culture-independent techniques, although often highly sensitive and specifi c, do not
provide information about the precise location, role or activity/inactivity of the
organism. Nevertheless, there have been dramatic improvements in diagnostic
methods, encompassing recent developments in molecular biology.
Keywords Diagnosis • Phenotyping • Serology • Molecular methods • Rapid
methods
Diagnosis has often appeared to be as much art as science, with a multitude of preferred methods adorning the notebooks of most diagnosticians. However, the rapid
acceptance of culture-independent, molecular-based methods has revolutionised
diagnostics in terms of accuracy and sensitivity. Yet, diagnosis may still be achieved
on purely histological material, with little effort made identify the pathogens. This
is especially true of some of the acid-fast bacterial fi sh pathogens. When identifi cation of the pathogen is attempted, it is a common fault that diagnosis proceeds with
emphasis on traditional biochemical tests designed originally for bacteria important
to human medicine. Consequently, a superfi cial glance at many laboratories would
suggest that diagnostic techniques for fi sh pathogens need to be brought up to date.
The question to be resolved is which is best – culture-dependent or culture independent approaches? Culture-independent methods will provide answers as to what is
present in the diseased animal, but the data do not necessarily refl ect the role or
relevance of any micro-organism in the host. It is to be hoped that any astute diagnostician considers all available information concerning a disease situation before
reaching a judgment. Useful information includes:
• Gross clinical signs of disease on individual fi sh;
• Internal abnormalities apparent during post-mortem examination;
• Histopathological examination of diseased tissues;
© Springer International Publishing Switzerland 2016
B. Austin, D.A. Austin, Bacterial Fish Pathogens,
DOI 10.1007/978-3-319-32674-0_13
Chapter 13
Diagnosis
Abstract Historically, scientists have seemed loath to make rapid diagnoses, preferring to adopt laborious testing regimes. Yet, diagnostic techniques have their
drawbacks insofar as it is not always certain that the actual pathogen is recognized.
Culture-dependent methods may highlight secondary invader or contaminants.
Culture-independent techniques, although often highly sensitive and specifi c, do not
provide information about the precise location, role or activity/inactivity of the
organism. Nevertheless, there have been dramatic improvements in diagnostic
methods, encompassing recent developments in molecular biology.
Keywords Diagnosis • Phenotyping • Serology • Molecular methods • Rapid
methods
Diagnosis has often appeared to be as much art as science, with a multitude of preferred methods adorning the notebooks of most diagnosticians. However, the rapid
acceptance of culture-independent, molecular-based methods has revolutionised
diagnostics in terms of accuracy and sensitivity. Yet, diagnosis may still be achieved
on purely histological material, with little effort made identify the pathogens. This
is especially true of some of the acid-fast bacterial fi sh pathogens. When identifi cation of the pathogen is attempted, it is a common fault that diagnosis proceeds with
emphasis on traditional biochemical tests designed originally for bacteria important
to human medicine. Consequently, a superfi cial glance at many laboratories would
suggest that diagnostic techniques for fi sh pathogens need to be brought up to date.
The question to be resolved is which is best – culture-dependent or culture independent approaches? Culture-independent methods will provide answers as to what is
present in the diseased animal, but the data do not necessarily refl ect the role or
relevance of any micro-organism in the host. It is to be hoped that any astute diagnostician considers all available information concerning a disease situation before
reaching a judgment. Useful information includes:
• Gross clinical signs of disease on individual fi sh;
• Internal abnormalities apparent during post-mortem examination;
• Histopathological examination of diseased tissues;