INTERVIEW TRANSCRIPT - B. Joseph Guglielmo, Pharm. D.

B. 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 Francisco.



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.

What 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?

Once again, 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 products.

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?

The potential 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, hazardous?

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?

Using other 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?

In addition 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 resort?

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 illnesses.

Do you have any comment on disease prevention, not using antibiotics, and the wider issue of how we are raising these animals and creating the disease?

Absolutely. 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?

Resistance, 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.