Pill poppers beware

-- The contribution of antibiotics in enhancing the quality of human life is well known. However, there is now growing evidence that these drugs cause substantial harm. Researchers in many parts of the world have found that a large amount of antibiotics, used by humans and administered to animals, is excreted out. They then get mixed with soil and create conditions that favour emergence of antibiotic-resistant bacteria.

How does it happen? Many of us have a propensity to pop antibiotics for trifle infections. These drugs are also administered to animals, sometimes even to promote their growth. Such indiscriminate use leads to the annihilation of numerous harmless bacteria, present in our bodies. These bacteria, in fact, protect us from invasion by numerous pathogens. They also suppress antibiotic-resistant bacteria, which are present in small numbers in our bodies. But antibiotics kill or suppress the growth of such useful microorganisms. Consequently, antibiotic-resistant bacteria get all opportunities to thrive. These pathogens can actually play havoc with people with low immunity. Antibiotic-resistant bacteria can also transfer copies of resistance-conferring genes to antibiotic-sensitive bacteria and make these microorganisms antibiotic-resistant.

Much the same happens in nature. Soils comprise a mixed bacterial population. Most of these microorganisms are actually quite beneficial for life. But antibiotics, dumped by humans and excreted by animals play havoc with the soil's bacterial population. They kill --or suppress -- the harmless bacteria. As a result, antibiotic-resistant bacteria multiply in soil. These microorganisms are even washed away by rains to streams and other water bodies. They subsequently make their way into bodies of fish and other marine creatures. These creatures are quite likely to transfer the antibiotic-resistant bacteria back to humans, if they are not properly washed before cooking.

The problem is acute In 2003, researchers of the Nouzilly, France-based Institut National de la Recherche Agronomique isolated a multi-drug-resistant strain of Salmonella enterica -- a common bacterium -- from fish samples imported to France from Thailand. In a similar investigation, 103 bacterial strains, obtained from freshwater salmon farms in Chile, were found to be resistant to oxytetracycline, amoxicillin, ampicillin, erythromycin and furazolidone.

The problem has also become quite common in India. Some time back, researchers of the Calcutta School of Tropical Medicine, Kolkata, isolated an antibiotic-resistant sample of the bacterium, Proteus vulgaris . The bacteriium, detected in external ulcers of fish, was resistant to streptomycin, chloramphenicol and tetracycline. Similarly, 319 strains of the water bacterium, Aeromonas hydrophila, isolated from fish and prawns, were found to be methicillin and rifampicin-resistant by researchers of Bharathiar University, Coimbatore, Tamil Nadu.

Use of antibiotics to treat bacterial infections in fish also contributes to the emergence of antibiotic-resistant bacteria in these creatures. These bacteria retain their characteristics well after the treatment is withdrawn, making fish consumers quite susceptible.

Even agriculture isn't spared Bacteria found in fruits and vegetables have also shown increasing propensity to antibiotic resistance. That's not surprising since antibiotics are used in agriculture, as well. A couple of years back, researchers from G N Khalsa College, Mumbai, found antibiotic-resistant bacteria in 120 raw vegetables and fruit samples. Similarly in 2004, researchers of the North Carolina State University, usa , found antibiotic resistant bacteria in vegetable samples collected from southwest us.

Scientists apprehend that the problem of antibiotic-resistance can take us back to the pre-antibiotic era. Restriction on application of antibiotics, meant for human use, in agriculture is the need of the hour. Also, we need not pop antibiotics for trivial maladies.

M K Chattopadhyay is with the Centre for Cellular and Molecular Biology, Hyderabad, Andhra Pradesh