Sunday, November 27, 2011

Environment: Bacteria are getting more and more resistant to antibiotics

Structure of a typical bacterial cell. Photo credit: Biology of Microorganisms Prentice-Hall

Dr Abe V Rotor

When Alexander Fleming discovered antibiotics in the early 19th century, the world rejoiced on this wonder drug that was to become the most effective cure against infection – from skin inflammation to tuberculosis.

What is this wonder drug, antibiotics? Antibiotics refers to any material that destroys or inhibits the growth of pathogens. It may be derived from fungi such as Pennicillin notatum, the mold Fleming accidentally found, to natural substances present in plants such as allicin and aliin in garlic, Allium sativum. Today antibiotics are available in many kinds and brands, many of which have the ending “mycin” like streptomycin and erythromycin.
Antibiotics saved countless lives during the Second World War. It brought hope to patients suffering of then incurable diseases such as venereal diseases, small pox and leprosy.

When antibiotics were first used as chemotherapy following successful experiments against infectious diseases, the problem of creating antibiotic-resistant bacteria was never considered seriously. The fact is that bacteria, like other organisms, have the ability to develop resistance against certain substances, especially if these are repeatedly used. This is the same principle to explain the buildup of immunity of insects to insecticide, thus next time you spray mosquitoes or cockroaches, you `need a higher concentration – or a more potent pesticide.

Biological Specialization

Imagine a population of bacteria crowding an injured tissue. Ideally the application of an antibiotic will wipe out the entire population. But this is not so. In the process there are survivors. These survivors pass on their acquired resistance to their progeny. To eradicate them you need to apply a dose higher that the previous one - or shift to another kind that is more potent. As this is repeated over and over, one can imagine the amount of resistance gained by the bacteria.

Thus we hear doctors prescribing higher dosages, say from 200 to 400 mg per dose, or extending the treatment of the disease. In many occasions doctors prescribe different antibiotics that are purposely more potent. Today we know of “second generation” antibiotics that offer the solution to bacteria, which can no longer be treated, by the antibiotics in the first generation or penicillin group.

Self- Medication Creates Resistant Bacteria

The emergence of resistant microbes is exacerbated by self-medication since many antibiotics are available over the counter. Any symptom of infection, whether viral or bacterial, is immediately confronted with antibiotics.

Wrong. Antibiotics are not effective against viruses. They are designed principally against bacteria. Therefore, influenza cannot be treated with antibiotics; it is the secondary infection by bacteria that the doctor targets when administering antibiotics. And there is a prescribed dosage for it and period of treatment. The condition of the patient at this time makes him prone to bacterial infection that principally attacks the respiratory system.


Media is part to blame for the overuse and misuse of antibiotics.

Imagine an advertisement showing the helplessness of patients who are not attended immediately with antibiotics. A scratch needs antibiotics. Sore eye for whatever is the cause must be treated with antibiotics. Zealousness over sanitation in the office, home, hospitals, includes the use of many kinds of germ-killing compounds and materials. Antibiotics are part of our every life. I overhead some guys taking antibiotics before spending a night in the red district. It is as if the prefix, anti, is an assurance of protection.

Mechanics of Resistance Acquisition

The rapidly increasing incidence of drug resistance is now recognized worldwide as a serious threat to the treatment of life-threatening infections in both humans and animals. Antibiotic resistance can emerge as a result of genetic change and subsequent selection process through the use of anti-microbial drugs. The initial appearance of a resistant bacterium in a susceptible population is often caused by mutation in a single bacterial gene. The frequency of such initial mutation may be low, occurring at a rate of one mutation in a population of several millions.

However, other bacteria can become antibiotic resistant at a much higher frequency merely by acquiring a gene from a bacterium that is already resistant. The genes for resistance can be transmitted or passed on from one organism to another by transformation, conjugation and transduction.

To illustrate, here are the three phases of development of resistant bacteria.

(A)
Mutation of a single gene in one member
of a population of millions of bacteria

(B)
A bacterium can acquire the mutant gene

(C)
The gene for resistance can be transmitted pr passed on from one
organism to another by transformation, conjugation or transduction

By all means let's maintain good health because good health is the most effective and practical assurance against disease. Let us not resort to self-medication, and this includes all kinds of medicine. The necessity of taking antibiotics is determined only by a medical doctor.

Resistant Bacteria in Gastro-intestinal Tract of Meat Eaters

If you are a meat eater, chances are you are harboring bacteria that are resistant to antibiotics.

In her doctoral dissertation at the University of Santo Tomas, Vicky Concepcion Mergal found out that drug-resistant strains of Enterobacter and Escherichia coli found in the gastrointestinal tract is related indirectly to ingestion of meat conditioned to antibiotics, or its combined effect with exposure to medication in cases of infectious diseases. How do we explain this findings?

The respondents in the study of Dr. Mergal are of two categories. One group consists of vegetarians and the other group of non-vegetarians or regular meat eaters. For the first group, the incidence of finding drug-resistant bacteria is very little. But in the second group – the meat eaters – the existence of drug resistant Enterobacter and E. coli is high.

The root cause: overuse of antibiotics in poultry and sivestock

Dr. Mergal’s adviser, Dr. Irineo Dogma, has the explanation why there is higher incidence of bacteria in the gastrointestinal tract of non-vegetarians because of their intake of meat. As a background to this contention, poultry, hogs and livestock are given consistently high ration of antibiotics in their feeds. This is to safeguard the animals from possible outbreak of diseases, which are a threat to business. Imagine a whole ranch wiped out by foot-and-mouth disease, or a battery of chicken with corriza, or a commercial piggery with scouring. Huge investments must therefore be protected with antibiotics even if the animals do not actually need it. It is because they have their own defense mechanism - natural immunity.

Resistance to antibiotics among bacteria is built this way. Repeatedly, more and more of these resistant strains develop, thus necessitating further increase in antibiotic dosage, or change to more potent antibiotics. What happens to the residue of the antibiotics in the body of the animal, or in eggs and milk?

Residual Antibiotics in Bad to Our Health

When we eat the meat, eggs and milk we are introducing into our body the antibiotic residues that our body does not need. In fact, its presence makes our immune system idle, so to speak. In the event that the supply of antibiotic residues stops, we become predisposed to infection and related kinds of disease because of the presence of resistant bacteria in our body. This explains the findings of Dr. Mergal, as well as the puzzling high rate of death due to infection – in spite of antibiotic treatment.

This leads us to recall the term, superbacteria and superbugs. These are the doings of man, his interference with nature, and abuses often in the guise of progress. I have the inkling that nature has its own ways of dealing with the folly and abuses of man, and one of them is the emergence of resistant organisms that threatens man himself. ~


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