Recent study has revealed that the number of drug-resistant tuberculosis cases can multiply and these TB superbugs, which are immune to treatment, could become a serious global threat.

Earlier studies showed that drug-resistant TB strains have lower transmission rate as compared to drug-sensitive strains. The recent study showed that antibiotic-resistant TB strains are equally capable of the transmission just like normal TB strain.

Inconsistent or partial treatment often leads to drug-resistant TB. One in three people has the TB bacterium but in most cases it does not cause illness.

Medical experts fear that although there is a decrease in the number of TB cases around the world but there is an increasing fear of the spread of the TB strain which is immune to any medicine.

A research team led by UNSW's Dr. Mark Tanaka studied epidemiological and molecular data from Mycobacterium tuberculosis strains isolated from Cuba, Estonia and Venezuela. Research team studied the relative "reproductive fitness" of resistant and drug-sensitive strains.