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Good aquaculture and biosecurity

practices to minimize AMRLarry A. Hanson

[email protected]

Aquatic AMR Workshop 1: 10-11 April 2017, Mangalore, India

FMM/RAS/298: Strengthening capacities, policies and national action plans on

prudent and responsible use of antimicrobials in fisheries

ANTIMICROBIAL RESISTANCE MANAGMENT

o AVOID DEVELOPMENT-

• Biosecurity

• Disease prevention

• Alternative treatments

• Judicious use

o REDUCE PERSISTANCE

• Crop rotation/complete harvest

• Monitoring and disinfection?

• Antibiotic use restriction or rotation

o AMR experience in channel catfish production

Biosecurity-Avoiding obligate pathogens and AMR strains

o Fish source- critical factor

• Indiscriminant use of antibiotics during early stages can result in build up in system

• Fry and eggs sometimes given prophylactic bath treatments during handling- these

may be critical during establishment of microbial flora and allow establishment of

AMR.

• Know how fish produced and antibiotic usage- hatchery GAP

• Due to economics of hatchery systems and susceptibility of young- improper use of

antibiotics at this stage is more common (also opportunity to spread pathogens and

antibiotic resistance through industry

• Disinfection of tanks and ponds between batches.

• Separation of eggs from brooders and disinfection of egg surface (iodine, formalin,

potassium permanganate)

Biosecurity- avoid obligate pathogens and introduction of AMR

o Surveillance, quarantine and monitoring

o Used of certified free stocks

o Use pathogen free water, and processed feeds or SPF live/fresh feeds

o Between farm security-

• On farm equipment, nets

• Limited access

• Cleaning/disinfecting trucks, trailers, boats entering facility

o Within farm security

• Avoid water movement between ponds

• Disinfect nets and equipment

• Predator and scavenger control- mammals, birds and reptiles can shed fish pathogens

Disease prevention- reduces need

for antibiotics

o If you don’t correct underlying cause

disease will reoccur after treatmentPathogen Host

Environment

Disease

Disease prevention

o Manage the environment to minimize stress and physical injury

• Water quality

• Handling

• Environment

• Manage predators

• Prevent aggression and cannibalism- remove dead

o Minimize viral, water mold and parasite diseases (Predispose fish to

bacterial disease and suppress feeding- resulting in subtherapeutic

treatments)

o Vaccines-if effective for bacterial pathogens and viruses

o Good quality feed, freshness and amount

Non-antibiotic alternatives

o Management to reduce pathogen load or transmission dose

• Fecal oral transmission- Allow time for gut to clear before feeding- reduces defecation

where feeding- ESC every-other day feeding during peak disease season

(feed restriction may help with others by reducing close contact)

o Chemical treatments that interrupt transmission or stimulate resistant state in

host

• Copper sulfate makes catfish less susceptible to columnaris disease

• Salt 1-5 ppt reduces F. columnare’s ability to adhere to fish (Used during hauling)

• Potassium permanganate oxidizer kills surface bacteria and free bacteria in the water

Judicious Use of Antibiotics-medicated feeds- minimizes selective

pressure

o Use when needed and effective

• Must be diseased- no prophylactic use, no use for growth promotion

• must be susceptible bacteria pathogen- susceptibility testing

• Fish must feed well enough to get a therapeutic dose

o Give for full treatment duration- antibiotic must persist long enough to kill

pathogen

o Use fresh good quality medicated feed- reliable licensed feed producer

o Careful feeding practices- avoid wastage- AMR can develop in bacteria that

grow in wasted feed

Judicious Use-

Antibiotics-medicated feeds- regulation

o Prescription- Licensed or certified health professional-requires VCPR

• Must know disease treated (has done the primary diagnosis- should follow up with AMR

testing)

• population activity (feeding well enough for treatment)

• Must assure that producer is understands proper safe application, rate, duration and

withdrawal time before slaughter and agrees to use it in that way

o approved antibiotics from licensed source, licensed feed manufacturer

• Approval for species, pathogen, rate of application and withdrawal time- drug company

must show efficacy, safety to user and fish and human food safety

o Record keeping- producer, veterinarian/ licensed fish health professional,

feed manufacturer

Judicious Use- Enforcement

o must be consequences for improper use

• Illegal drugs human food chain- serious repercussions- human health and product

• Government agency – in US FDA

• Enforcement branch- actively seeks out any illegal drug usage and presence on

facility- results in condemnation of fish, large fines and imprisonment

• Monitors and traces prescription use drugs- through feed manufacturer

• Fillet (human food) monitored for residue if any found condemn lot, recall any on

market and trace back to farm source

• Licensing (drug company, feed mill, fish health professional) - assigns legal

responsibility and can inappropriate activity can result in revocation

• Can be industry driven through contracts or cooperatives

REDUCE PERSISTANCE

o Minimize use-AMR is a natural process. There is cost to the bacteria to

maintain this state, minimal antibiotic use will minimize selective pressure

and result in lower numbers of AMR pathogens.

o Complete harvest and disinfection of production system prevents build up in

system.

o Crop rotation if practical- breaks pathogen cycle

o Voluntary antibiotic use restriction or rotation on a facility for 2-3 production

cycles.

Experience in Channel catfish production

o Major pathogens

• Flavobacterium columnare

• Edwardsiella ictaluri (Enteric septicemia of catfish) and E piscicida

• Aeromonas hydrophila

o Approved antibiotics- All medicated feeds all by Veterinary prescription in

2017 (Terramycin and Romet OTC in 2016).

Terramycin-Oxytetracycline 10 days- 21 day withdrawal (rarely used- has been in past)

Romet- Sulfadimethoxine-Ormetoprim 5 days- 3 day withdrawal (occasionally used)

Aquaflor- Florfenicol 10 days- 15 day withdrawal (commonly used)

o Cost $800 per ton vs. $390 for non-medicated

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

growthJun 29

Brood pond

Hatchery

Grow out

Harvest

stocking

Fingerling pond

Vaccinate and stock fry

7-8 days post hatch

H

GO

Catfish production Stock fingerlings

Continuous production allows pathogen and AMR build up

Routine stress management

o Dissolved oxygen intensely managed over summer months

o Chlorides maintained above 100ppm to reduce nitrite toxicity

o Use fresh, well formulated feeds

o Stock fish in cool months to reduce handling stress

Columnaris- Management

o Avoid damaging mucus layer-

• Handle during cool weather

• Use smooth surfaces or water cushion when handling

• Treat hauling tanks with 1-3 ppt salt

• Avoid damage to gills- particulates, ammonia, parasites

o Manage ESC, Winter mortality, CCV

o Vaccinate (effectiveness in fry not great, likely better in older fish)

o Treatment with copper sulfate has been shown to help

o Antibiotic medicated feed- Aquaflor labelled, Terramycin not labelled effective

but not used, Romet not labelled and may not be effective

Enteric Septicemia of catfish-management

o Avoid stress (DO and Nitrite)

o While in 22-27 C window feed on alternate days

• This reduces transmission- enteric pathogen. Gut clearance before feeding reduces

bacterial shedding when fish concentrated for feeding.

Wise, D.J., Johnson, M.R., 1998. Effect of feeding frequency and Romet-medicated feed on survival, antibody

response and weight gain of fingerling channel catfish (Ictalurus punctatus) after natural exposure to

Edwardsiella ictaluri. Journal of the World Aquaculture Society 29, 170-176.

o Vaccination- helps in fingerlings but losses still occur

o Antibiotic treatment- Aquaflor (labelled), Romet (labelled), Terramycin (not

labelled)

New Disease: Virulent Aeromonas hydrophila (VAH)

Courtesy of William Hemstreet

High losses over a short time in

warm months.

First seen in 2009

Most important cause of disease

in larger catfish

Distinct strain

Biosecurity: limiting VAH Spread

o Moving infected fish?-not

common

o Contaminated equipment

& Water (correlation with

seining frequency-

Bebak et al. 2015. Prev.

Vet. Med. 118, 161-168)

o Predators and Scavengers. Experimentally

shown to survive through gut of Egrets,

pelicans, wood storks and cormorants

Human Natural

Management

o Hold off feed at first signs of disease

o Antibiotic medicated feed- aquaflor (Working on label, extra label use),

Romet (not labelled), Terramycin (labelled)

o Often re-occurs after treatment period finished. Suspect environmental

factor(s) involved.

Observed antimicrobial resistance 2016 MSU-CVM DL

Number

evaluated

percent

Florfenicol

percent

Romet

percent

Terramycin

percent

MDR

Aeromonas hydrophila 97 1.03 0 1.03 0

Aeromonas sobria 71 12.6 1.41 49.3 2.82

Aeromonas caviae 4 0 0 0 0

Edwardsiella ictaluri 41 14.6 0 12.2 12.2

Edwardsiella piscicida 18 5.55 0 0 0

Plesiomonas shigelloides 7 71.4 14.3 85.7 71.4

Streptococcus 4 0 0 0 0

Total 242 9.09 0.826 19.4 4.96

67 of A. sobria were with F. columnare, 7 were with E. ictaluri, 3 parasites, I saprolegina

AMR in catfish pathogens- Observations

o Highest resistance seen in Aeromonas sobria

• This is a secondary pathogen, not usually the target of antibiotic treatment but often

present during columnaris disease

• Also highest resistance to terramycin which is rarely used now

o Second highest level of resistance seen in E. ictaluri

• Most are resistant to both Aquaflor and Terramycin

• Early research by Cooper et al. 1993 demonstrated a Romet and Terramycin resistance

mediated by an R plasmid that was very similar to a R plasmid isolates from an E. coli.

o Industry has seen increasing levels of Aquaflor resistance. May seriously

impact treatment options.

o Romet resistance subsided rapidly when it was used less often

Summary

o Disease management is the most important component for AMR management

o Antibiotic resistance will develop and may occur in non-target pathogens

o Industry needs to be proactive to minimize the impact