TRANSCRIPT - B. Joseph Guglielmo, Pharm. D.
Joseph Guglielmo is a Director of Antimicrobial Management
Program at the University of California San Francisco. His
primary role is researching the responsible use of antibiotics
at the medical center at the University of California San
Are the amount of antibiotics used in the aquaculture industry less
than what is commonly used in land-based animal husbandry operations,
such as poultry and swine?
The same sort
of debate has taken place with the animal husbandry industry. They
discuss coming up with a potential estimate on what percentage of
antimicrobial use in the United States or worldwide is for human
use versus animal use. It becomes quite debatable. No one really
knows the true answer.
Saying that aquaculture uses quite a bit less, it doesn't tell me
that much, because what you're really saying is that it's a percent
of an unknown that already exists. We don't really know how much
animal use of antibiotics takes place relative to humans. I would
still say I'd have very much concern about any level of antibiotic
being used in a population of animals.
are the greater dangers involved with the dispersal of these chemicals
when they are used in an aqueous environment versus a land-based
farm where they're raising swine or poultry?
we have a bit of a problem with aquaculture and antibiotic use in
that there are a number of unknowns. Those unknowns include: number
one, how much is truly being used? Number two; what is the level
of which these antibiotics are being removed from this ecosystem
whereby these shrimp are being fed these antibiotics? I would say
if you compare it with what we do know with antibiotics and animal
husbandry, one has to once again be concerned that there are significant
risk. Those risks primarily relate to the development of antibiotic
resistance bacteria, which could be harmful to the animals that
are being fed it and ultimately to the humans that consume these
Does it concern you that these supply stores in Thailand, China
and Vietnam require no prescription and many of the growers often
have little sense as to whether their shrimp are infected with a
virus or a bacteria?
I have the same
comment I have regarding the use of antibacterials with human infection.
People do not fully understand the disease they are treating, i.e.
the public. It's ineffective to use antibacterials for a disease
state for which a virus is the cause. Similarly, you have individuals
that have virtually no understanding of whether or not the shrimp
are being infected by bacteria, virus, or fungus. Using an antibacterial
for a disease will have not only no benefit but also the ability
to alter the ecosystem in the way of bacterial resistance.
Do you have
any concerns about disease resistant pathogens or the chemicals
themselves getting out to wild shrimp or to other marine life?
I would have
a couple of concerns. My primary concern is, once again there are
numerous biological models that show that exposure to antibacterials
can result in antibacterial resistance. Those antibacterial resistant
bacteria can spread to humans and cause disease, and mortality associates
with that. Similarly, if in fact an antibacterial is indiscriminately
used in aquaculture, specific to shrimp farming, I would be concerned
with the same sort of principal. If in fact you were using drugs
that also happen to be used in the treatment of infections for humans,
there would be the creation of antibiotic resistant organisms that
would now make it more difficult to treat human infection.
The second concern
I would have is that there is a lot we don't understand about good
flora. In humans we know that there is a very delicate balance between
good bacterial flora and, say, the bad bacterial flora. If in fact
you indiscriminately kill off the good bacterial flora it sets off
a sequence of events where you get infections with organisms you
normally would not. It is hypothetical I realize. I would be concerned
that these shrimp that may depend on flora, be it viruses, bacteria,
fungi, or whatever, they might be might be negatively impaired as
a result of indiscriminate antibacterial use.
What are the potential problems of the indiscriminant use of antibiotics
on shrimp farms?
problems of indiscriminant antibacterial use on shrimp farms are
hypothetical but very real based on other biologic systems that
have taken place. You may alter good flora that exists in this ecosystem
in the shrimp itself and other co-inhabiting wildlife, by virtue
of indiscriminant use of antibacterials. We don't know what the
results will be. It could make shrimp less healthy or could potentially
have an effect on humans that ingest these shrimp.
Are the trace amounts of antibiotics in the prawns that people consume,
I don't know
what research has taken place to show how much of an antibacterial
is in these prawns. However, there's little doubt that even trace
amounts of not only antibiotics but also any potential toxins can
be cause effects in humans. An example is chloramphenicol, it is
an antibacterial that is used in this industry and has been well
demonstrated that this agent is associated, in some cases, with
an irreversible anemia in humans that is not dose related. It just
relates to being exposed to the antibacterial. Another example would
be sulfa-like drugs, which we would call sulfonamides, which are
also used in this industry. Some people are very susceptible to
the negative effects of those in the way of terrible skin rashes.
So that would be another hypothetical possibility that might be
associated with inadvertent exposure to the sulfa drugs.
What are the chances of someone eating a shrimp that contains a
pathogen that is drug resistant?
models that have been very well detailed, it has been shown that
in fact animals fed a given antibiotic, can after that point harbor
the antibiotic resistant organism. Then, the human, after having
eaten that resistant antibiotic, let's say poultry, comes down with
an antibiotic resistant bacterial disease. So, it certainly exists
as a possibility in aquaculture as well because many times the drugs
that are used in aquaculture in way of antibiotics are in fact the
same drugs that are used to treat humans. So, it is certainly possible
but to my knowledge it is not proven at this point.
What is the problem with chloramphenicol?
to chloramphenicol, which is an older antibacterial. Tetracyclines
and sulfa drugs, which are older antibacterials, still have a lot
of usage today in human infection. Interestingly, a drug that is
commonly used is norfloxacin. Norfloxacin essentially is exactly
the same class of antibiotics as the drug ciprofloxacin, which is
Cipro. Those agents have very wide use in the treatment of infections
throughout the world. There is also a resistance problem with these
agents in the treatment of urine infections, lung infections and
many others as well.
Is ciprofloxacin a new class of antibiotics that is used as a last
The class of
antibiotics also known as quinolone antibiotics, which include norfloxacin,
is actually used in the treatment of bladder infections worldwide.
Ciprofloxacin is a last line agent in the treatment of certain bacterial
Do you have any comment on disease prevention, not using antibiotics,
and the wider issue of how we are raising these animals and creating
Well, if you don't mind I'm going to use another analogy that I
am very familiar with. There are a number of bacterial diseases
that you can give antibacterials and prevent them somewhat from
occurring. The very best way to prevent some of these bacterial
illnesses, for example, is to be vaccinated for it. Then you don't
get the disease and you tend not to need antibiotics. A large reason
that antibacterials are used prophylactically in aquaculture is
because of the density of the population, in this case the shrimp.
If a few shrimp get infected, they all get infected. So, perhaps
it's time to rethink the way the practice takes place, think of
the economic ramifications etc., and see if there might be a better
way to manage these shrimp in these very tightly packed areas.
Is there anything you would like to add?
to me, is the biggest issue. It's particularly an issue anytime
a practice takes place to prevent infection in animals or in fish
or in shrimp. If that same antibiotic or antibacterial is used in
humans, in the active treatment of disease, that is a recipe for
disaster. If antibacterials are to be used in that model, they should
not pass over into the sphere of the antibacterials that are absolutely
necessary in the treatment of human infection.
Do consumers have a way of participating in the solution by taking
more care in the products they buy?
I do know there is a sub group of all the providers of these products
that call themselves organic. You can ask these individuals "can
you guarantee that the shrimp I am buying were treated prophylactic
with antibacterials?" That information can be known. If that
information is not known and cannot be provided then you can argue
that there is a very good chance that the shrimp that you are buying
have been treated before that time with antibacterials. The issue
once again is how big is that slice of the pie right now and it
goes back to the economic model once again. They are more expensive.
We buy vegetables and fruits organically and those also are a little
more expensive. It's up to the public and the individual whether
or not you want to know that.