Drug resistant TB breaks out in India

A new strain of TB has broken out in India and Iran. The new strain, which has proven immune to the antibiotic drugs usually used against it, has sent doctors all over the World into a panic. While information on the Iran outbreak has proven scant, reports from India have tallied the size of that outbreak at 12 people.

The potential for a drug-resistant strain of Tuberculosis (TB), or any other infectious disease, has been known for years. Much of the blame has been put on the overuse of antibiotics as easy cure-alls. In any sufficiently large batch of bacteria, there will always be a few cells which are immune to the antibiotics. When the drugs are applied, those bacterium will survive and reproduce – passing on their genes and creating a population with an even higher rate of immunity than before, and eventually creating a strain which is completely immune to the drug.   

"Bacteria, like any other organisms, are subjected to constant genetic mutations," said Ping Liang a professor in the Brock University Biology Department. "The genetic differences may lead to variations in the drugs targets or differences in metabolizing the drug."

According to Liang, India's large population, combined with a "poorly run TB control program," were the likely reasons why the outbreak began there specifically.

Antibiotics usually work by inhibiting specific processes in the bacterium's body which are necessary for it to live. Penicillin, probably the most famous type of antibiotic, works by interfering with the bacterium's ability to repair its cell wall – thereby causing it to dissolve. Rifampicin, which is commonly used to treat TB, blocks the cell's ability to transmit Ribonucleic acid (RNA), inhibiting the creation of new proteins. According to Liang, doctors facing a strain that is immune to the usual course of treatment have limited options.

"The best option is to try different drugs, " Liang said.

Drug resistance, as a function of natural selection, is impossible to prevent entirely. However, doctors have developed several protocols to follow when proscribing antibiotics, in order to do so "rationally".

"Irrational use of medicines is a major problem Worldwide" said the World Health Organization (WHO) on their Web site. "[We estimate] that more than half of all medicines are prescribed, dispensed or sold inappropriately, and that half of all patients fail to take them correctly."

According to Liang, this specific strain is unlikely to be especially virulent, as the disease's propensity to mutate — which is what caused its immunity in the first place — has made it less durable. However, the effect of drug resistance is accumulative, meaning that the bacteria will likely become stronger over time.

"Normally, a drug resistant pathogen may not be as robust as its predecessor at the beginning due to its biological adaptability, as well as the small size of its niche" Liang said.

"For pathogen-derived diseases, the drug resistant pathogens stay and accumulate over time. Therefore, we humans could run out of options one day [...] and this could be a serious threat."