Veterinary products and aquatic animals

Veterinary products and aquatic animals

Peter Smith

Chair OIE ad hoc Group on the responsible use of antimicrobials in aquatic animals

Veterinary products

Vaccines

Disinfectants

Anti-parasitics

Antibiotics

Antibiotics

FAO Definition‘a drug of natural or synthetic origin, with the capacity to inhibit the growth of or to kill microorganisms. Antibiotics that are sufficiently non-toxic to the host are used as chemotherapeutic agents in the treatment of infectious diseases of man, animals and plants.’

Reasons for antibiotic use in aquaculture

Prevention (good husbandry and correct use of vaccines) is the best way of reducing disease risks

but

When bacterial infections occurs in farmed animals antibiotics are the only therapy that will

reduce loses

Reasons why antibiotic use must beprudent

Antibiotics are powerful chemicals - biologically active at low concentrations

Aquacultural use involves the deliberate introduction of these chemicals into the food chain and the environment

Use of antibiotics lead to the emergence of resistant bacteria and resistance compromises their value as therapeutic agents

Presence of residues may affect consumers of aquaculture products

Public perception of a “drug-based” industry and results in reduced market acceptability of aquaculture products

Resistance to antibiotics

Resistance and aquatic animal health

There is clear evidence that resistance to antibiotics has emerged when these agents are used in aquaculture

The more we use (and misuse) these agents the smaller is the chance that antibiotics will be effective therapeutically

We run the risk of entering the ‘pre-antibiotic’ era

Resistance to antibiotics

Resistance and human health

Resistance to antibiotics is global

There is a risk that antibiotic resistance selected by aquacultural use will compromise therapy of human infections

Pressure from human medicine (WHO) may reduce availability of antibiotics to aquaculture

Presence of unacceptable residues

Presence of any residues of banned antibiotics

or

Presence of levels of other antibiotics above maximum allowed limit

Will have major trade implications

Overall strategy to ensure prudent use

Regulation

Monitoring

Education

A new draft chapter of theOIE Aquatic Animal Code

is being prepared

It will primarily address issues of the regulation and the monitoring/surveillance of

the use of antibiotics in aquaculture

This talk is an introduction to some of these issues

Current global status

There is huge variety in the extent and the style of regulation and monitoring/surveillance of antibiotic use in aquaculture

Some authorities have very sophisticated procedures but the majority, including many responsible for large production volumes, have not


Regulation

Central to regulation is the licensing of antibiotic containing products

by the granting of

Marketing Authorizations


Regulation

Very few antibiotics are licensed for aquaculture

Many countries have licensed no antibioticsSome have only licensed a few (2-4)

Some large industries (shrimp) have no licensed antibiotics


Monitoring

We have little (quality) information on the consequence (target bacteria resistance) of

antibiotic use in aquaculture

We have no accurate estimates of the amount of antibiotics used in aquaculture

The way forward

The way forward - Regulation

Aims

To ensure that antibiotics used in aquaculture are safe to the animals treated and to the consumers

To ensure that antibiotics are used in a way that is likely to be efficacious (cost/effective)

To ensure all stakeholders are informed of their duties and responsibilities


Regulations based on Marketing Authorization

Only products for which MA have been granted should be used in aquaculture

MA will facilitatecorrect product labeling

and definition ofthe responsibilities and duties of all stakeholders


Marketing authorizations

Safety (treated animals, users and to consumers)

and

Efficacy


Safety to consumers

Maximum residue level (MRL)independent of species and rearing conditions - internationally set

Withdrawal timetime after therapy when residue is below MRLdependent on species and rearing conditions – locally set


Efficacy

Establish thata specified dose regimen delivered

using a specified antibiotic containing product will control loses resulting from a specified bacterial infection

of a specified speciesunder specified environmental conditions


Problems with basing regulation on MA

MA are expensive and time-consuming to produce

(who pays?)

MA are specific but disease conditions encountered in aquaculture are diverse


Problems with basing regulation on MA

There will always be a need for extra/off label

use of antibiotics in aquaculture

The way forward – Monitoring resistance

Information on resistance in target bacteria is essential:

to ensure individual therapies are rational and prudent

to understand emerging patterns of resistance nationally, regionally and globally

to inform risk assessment


We are in the process ofstandardizing and harmonizing laboratory methods

for measuring susceptibility in aquatic bacteria

We possess no quality information on resistance in bacteria that infect fish

Embarrasing fact

After 50 years of research we have no clear procedures for establishing if a bacterium isolated from an aquatic animal will be

resistant or sensitive to an antibiotic therapy


Determining resistance involves 2 stages

Development of appropriate standardized laboratory protocols

Developing interpretive criteria that allow meaning (sensitive/resistant)

to be given to the results of these laboratory tests


Test protocols

There is general agreement that the test protocols outlined in the CLSI documents

M42-A and M49 -A should be adopted

Current status of CLSI resistance methods

Test protocol Interpretive criteriaAeromonas salmonicida + +

Aeromonas spp +Edwardsiella spp +

Flavobacterium spp +Photobacterium spp. +Streptococcus spp. ?

Photobacterium spp +Vibrio spp +

Piscirickettsia salmonis

Vibrio salmonicida ?Tenacibaculum maritimum ?

Francisella spp ?

We know how to do the tests

but

We don’t know what the results mean

Current status of CLSI methods

Interpretive criteria

There is an urgent need for progress

Progress can be made on a species by species basis

Not all species are relevant to all industries or all regulatory authorities

The work required to set criteria for one species is not expensive or time-consuming

The way forward – Monitoring use

Data on how much antibiotics are being used is essential:

to understand emerging patterns of resistance

to inform and monitor strategic planning

to perform risk analysis

The way forward – Monitoring use

Use data requirementsEssential

Absolute amount (kg active drug) usedAnimals treated (species, number, weight)

Rationale for use (diagnosis, therapy/prophylaxis)

AdditionalMode of administration, type of husbandry system, environmental conditions etc

Risk analysis

What are the risks that use of antibiotics in aquaculture will select for resistances that will have a negative impact on human therapies?

A very difficult question to answer

Risk analysis

Risks associated with aquacultural use much less than those associated with use in

land-based agriculture

Risk primarily associated with selection of transferable resistance factors in

environmental bacteria

Risks associated with resistant bacteria in aquaculture products less important

Antimicrobial Resistance (AMR) Risk Analysis in Aquaculture

Discussion on the applicability of risk analysis principles for AMR in aquaculture

Thursday, 30 June 2011 8:30 amSpeakers Room/Salon Republicco

To receive a copy of a white paper describing the topic drafted by the OIE ad hoc Group on antimicrobial resistance in aquatic animals send a message to

[email protected]

Prudent use of antibiotics

Farmers buy and use antibiotics because they think/hope that it will increase their profits

Much use by farmers is inappropriate and imprudent

The greatest gain in prudent use and economic efficiency will be achieved by providing farmers with quality advice

Prudent use of antibiotics - education

Education programmes to train farmers and their on-farm advisors in the

correct use of antibioticsand

the provision of adequate and local diagnostic and antibiotic susceptibility testing

services

Will greatly reduce imprudent use

Documents

Veterinary products and aquatic animals