Responsible use of antibiotics in aquaculture - Food and Agriculture

110 Pages·2006·0.72 MB·English

Cover illustration:
Artwork composition by A. Ohene and H. Lupin; photos by H. Lupin (China, 2004).
Responsible use of FAO
FISHERIES
TECHNICAL
antibiotics in aquaculture PAPER
469
by
Pilar Hernández Serrano
Chief, Food Microbiology Chair, Faculty of Pharmacy
Central University of Venezuela
Caracas
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Rome, 2005
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or concerning the delimitation of its frontiers or boundaries.
ISBN 92-5-105436-3
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© FAO 2005
iii
Preparation of this document
“Antibiotic resistance as a phenomenon is, in itself, not
surprising. Nor is it new. It is however, newly worrying
because it is accumulating and accelerating, while the world’s
tools for combating it decrease in power and number.”
(IOM, 1998)
With this statement in mind, and considering that prompt action is needed to reduce
the overall misuse of antibiotics in all areas – human medicine, veterinary medicine,
animal production and plant protection – the Fish Utilization and Marketing Service,
Fisheries Division, FAO, took the initiative to develop this review, with the aim of
raising awareness of the antibiotic resistance problem in fish farming and related sectors,
promoting prudent use of these drugs according to the FAO Code of Conduct for
Responsible Fisheries.
This work focuses on antibiotics misuse and the concomitant threat of resistance
development, considering this topic to be a public health concern that affects the
population worldwide. Aspects such as the toxicity and allergic effects of antibiotic
residues, the mechanism of transmission of antimicrobial resistance and environmental
impact were also taken into account.
As the terms “antibiotic” and “antimicrobial” are often used indiscriminately, it
should be noted that, for the purposes of this document, discussion is limited to just
those antibiotics as defined in the glossary, although many aspects of the topic may be
common to other antimicrobials used in animal husbandry or aquaculture.
Important notice
Information regarding antibiotics in use, authorized or banned should be read in
relation to the data and other information of the reference. Since the status of veterinary
regulations varies very often in many countries, the interested reader should reconfirm/
update the specific information. Information given in this review is mainly for didactic
purposes and in support of responsible use of antibiotics in aquaculture.
iv
Abstract
Antibiotics are drugs of natural or synthetic origin that have the capacity to kill or to
inhibit the growth of micro-organisms. Antibiotics that are sufficiently non-toxic to
the host are used as chemotherapeutic agents in the treatment of infectious diseases of
humans, animals and plants. They have long been present in the environment and have
played a crucial role in the battle between man and microbe.
Many bacterial species multiply rapidly enough to double their numbers every
20-30 minutes, so their ability to adapt to changes in the environment and survive
unfavourable conditions often results in the development of mutations that enable the
species to survive changing external conditions.
Another factor contributing to their adaptability is that individual cells do not rely on
their own genetic resources. Many, if not all, have access to a large pool of itinerant genes
that move from one bacteria cell to another and spread through bacterial populations
through a variety of mobile genetic elements, of which plasmids and transposable
elements are two examples. The capacity of bacteria to adapt to changes in their
environment and thus survive is called resistance.
Drug choices for the treatment of common infectious diseases are becoming
increasingly limited and expensive and, in some cases, unavailable due to the emergence
of drug resistance in bacteria and fungi – resistance that is threatening to reverse much
medical progress of the past 50 years.
Dissemination of resistant micro-organisms may occur in both hospitals and
communities. It is recognized that a major route of transmission of resistant micro-
organisms from animals to humans is through the food chain.
In aquaculture, antibiotics have been used mainly for therapeutic purposes and as
prophylactic agents. The contribution to antimicrobial resistance of antibiotics used in
aquaculture is reviewed here, using a risk analysis framework. Some recommendations
on responsible conduct in this context are proposed, aimed at diminishing the threat of
build up of antimicrobial resistance.
Hernández Serrano, P.
Responsible use of antibiotics in aquaculture.
FAO Fisheries Technical Paper. No. 469. Rome, FAO. 2005. 97p.
v
Acknowledgements
The author wishes to express her special gratitude to Mr Hector Lupín for his various
suggestions during the preparation of this document.
Many thanks go to the Consejo de Desarrollo Científico y Humanístico (Council
for Scientific and Humanistic Development) of the Universidad Central de Venezuela,
which co-supported Professor Pilar Hernández during her period of study in Rome.
The author is also grateful to Mrs Wilma van Kessel and Ms Cristina Zuccaroli for
their patience and diligence in editing and document layout.
Final language editing and preparation of the publication were by Thorgeir
Lawrence.

vii
Contents
Preparation of this document iii
Abstract iv
Acknowledgements v
Acronyms ix
1. Introduction 1
2. Antibiotics 3
2.1 Definition of antibiotics 3
2.2 Mechanism of action of antibiotics 3
2.2.1 Anti-infectious agents 3
2.2.2 Growth promotion 3
2.3 Classification of antibiotics for veterinary use 4
2.3.1 Beta-lactams 4
2.3.2 Macrolides 5
2.3.3 Spectinomycin (Aminocyclitol) 6
2.3.4 Chloramphenicol 6
2.3.5 Florfenicol (Fluorinated derivative of thiamphenicol) 6
2.3.6 Tetracyclines 6
2.3.7 Quinolones 7
2.3.8 Sulphonamides 7
2.3.9 Lincosamides 7
2.3.10 Rifampin 8
2.3.11 Aminoglycosides 8
2.4 Antibiotics banned for animals intended for food production 8
2.5 Antibiotics authorized for use in aquaculture 9
3. Risk assessment 11
3.1 Hazard identification 11
3.1.1 Antimicrobial resistance 11
3.1.2 Epidemiology of antibiotic resistance 11
3.1.3 Antimicrobial resistance in aquaculture 21
3.1.4 Mechanism of resistance transfer 26
3.2 Hazard characterization 30
3.2.1 Human health risks associated with the use of antibiotics in aquaculture 30
3.2.2 Environmental risks 33
3.3 Exposure assessment 34
3.3.1 Guidelines on the establishment of MRLs 36
3.3.2 Assessing the effects of antimicrobial residues in food on the human
intestinal microflora 38
4. Risk management options 41
4.1 At regulatory level 41
4.1.1 Considerations from international forums 41
4.1.2 Laboratory methods for the detection and quantification of antimicrobial
resistance 48
4.1.3 Methods of analysis and sampling for antibiotics residues 50
viii
4.2 At industrial level 52
4.2.1 Approaches to minimizing antibiotics use in food-animal production 52
5. Risk communication 65
5.1 Promoting the prudent use of antibiotics in human medicine 65
5.2 Promoting the prudent use of antibiotics in veterinary medicine and
animal production 70
6. Recommendations 73
7. References 75
Glossary 89