Sunday, February 20, 2011

How Bacteria Become More Resistant to Antibiotics

Cell being attacked by bacteria. Painting in acrylic, AVR 2003

Abe V Rotor

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

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), or natural substances present in plants such as allicin and aliin in garlic (Allium sativum). Today, antibiotics are available through many brands, ending in “mycin” (like streptomycin and erythromycin).
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Antibiotics brought hope to patients suffering from once incurable diseases such as venereal diseases, small pox and leprosy. During World War II, antibiotics saved countless lives.
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When antibiotics was 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 same principle explains the buildup of insect immunity to insecticide. If we overuse this substance, next time we spray mosquitoes or cockroaches, we may need a more potent pesticide to do the job.

Biological Specialization

Imagine a population of bacteria crowding themselves inside of an injured tissue. Ideally, the application of an antibiotic will wipe out the entire population. But this is not always the case. Sometimes there are survivors. These survivors pass on their acquired resistance to their progeny. To eradicate the survivors and their progeny, you need to apply a higher dosage of antibiotics, or shift to a more potent kind. As this is repeated continuously, the bacteria continues to gain renewed resistance.

Thus we hear about doctors prescribing higher dosages for our recuperation, or extending the treatment time period. In many occasions, doctors prescribe different and, purposely more potent antibiotics. Today we speak of “second generation” antibiotics that eliminate bacteria resistant to antibiotics of the “first generation” (penicillin) group.

Self- Medication Creates Resistant Bacteria

The emergence of resistant microbes is exacerbated by human self-medication, since many antibiotics products are available over the counter. With any symptom of infection, whether viral or bacterial, we immediately confront it with antibiotics without getting a prescription. This is wrong. In the first place, antibiotics is not effective against viruses, only against bacteria. Therefore, influenza cannot be treated with antibiotics; it is the secondary bacteria infection that the doctor targets when administering antibiotics. There is a prescribed dosage and period of treatment based on laboratory tests. The condition of the patient must also be factored in the cure as he may be prone to bacterial infection which attacks the respiratory system, causing pneumonia. There are also side effects of antibiotics that may impair organs such as the kidney and liver. All these are considered by doctor when prescribing antibiotics.

Mass media is partly to blame for the misuse of antibiotics. Advertisements show patients helpless when they are not attended to immediately with antibiotics. A person with a scratch reaches for antibiotics. Over zealousness for sanitation in the office, home, hospitals, often times includes many kinds of germ-killing compounds. Antibiotics becomes a part of our every life. Overheard were some men allegedly taking antibiotics capsules before entering a red light district. It is as if the prefix, anti, gives an assurance of protection.

Mechanics of Resistance Acquisition

Bacteria’s rapidly increasing incidence of drug resistance to antibiotics is now recognized worldwide as a serious threat to the treatment of life-threatening infections. Such resistance will result into genetic changes where the selection process is made 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 level of frequency merely by acquiring a gene from an already resistant bacterium. The resistant genes can be passed on from one individual bacterium to another by transformation (genetic modification of a bacterium by incorporating freed DNA from another ruptured bacterial cell), conjugation (fusion or union of two bacterial cells) and transduction (transfer of genes from one microorganism to another by viral agent).

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
or passed on from one organism to another
by transformation, conjugation or transduction.

Resistant Bacteria in Gastrointestinal Tract of Meat Eaters

In her doctoral dissertation at the University of Santo Tomas, Vicky Conception Mergal discovered that drug-resistant strains of Enterobacter and Escherichia coli bacteria found in human gastrointestinal tracts are indirectly related to ingestion of meats conditioned to antibiotics. In her study, Dr. Mergal divided her respondents into two categories. One group consisted of vegetarians and the other group of regular meat eaters. For the first group, the incidence of drug-resistant bacteria is very low. But in the second group, the meat eaters, she found the presence of drug-resistant Enterobacter and E. coli to be unacceptably high.

Overuse of Antibiotics on Poultry and Livestock

As a general procedure, poultry, hogs and livestock are consistently given high rations of antibiotics as feed additives. This is to safeguard the animals from possible pestilence or outbreak of diseases. Without it, whole ranches could be wiped out by foot-and-mouth disease, or rows of poultry farms felled by corriza, or pens of high breed pigs decimated by scouring. The animals do not actually need antibiotics, but to protect their huge investments, businessmen introduce this medication nevertheless. In reality, animals have their own defense mechanism of natural immunity.

When people consume commercially raised meats, they, too, develop a resistance to antibiotics. To kill the resistant strains in our bodies, higher dosages or more potencies of antibiotics will be needed.

Residual Antibiotics in Bad to Our Health

Remember, when you consume pork, beef, chicken, eggs or milk from animals treated with mega doses of antibiotics, you become a repository of antibiotic residues you do not need. When you do get sick, more medication will be needed to get you well. The presence of antibiotics inside us invariably takes over the functions of our immune systems. In the event that the supply of antibiotic residues stops, we become predisposed to infection and related kinds of diseases because there is nothing to suppress the resistant bacteria in our bodies.

Nature has its own way of dealing with man’s folly. In this instance, it is the emergence of resistant organisms that threatens man himself.

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Living with Nature in Our Times, AVR 2011

1 comment:

Claud said...

This is very informative. Thank you for sharing.