Minute microbes are ironically the largest killers of humans throughout history. In fact Tuberculosis deaths worldwide is 1 billion over the last two centuries.1 In order to put it in perspective, the world population in 1800 was 1 billion.
The advent of Salvarsan in 1909 and the antibiotic era has curbed the encroachment of microbes to some extent. Antibiotics have literally been lifesavers. But there is a constant race to develop new antibiotics against infectious organisms since they rapidly develop resistance.
Consequently, in the United States, more than 99,000 people die each year from hospital acquired bacterial infections.2 In the European Union more than 25,000 people die each year from multi-drug resistant bacteria.3 These deaths are due to certain bacteria acquiring resistance to multiple drugs. This leads to an estimated medical cost per patient for a drug-resistant infection to range from $18,000 to $29,000.2
Actually, new antibiotics take about 3 years to be developed and the microbes take about 3 months to develop a resistance.1 There is a drought in discovering new classes of antibiotics. In fact, since the 1970s there have been no new classes of antibiotics that have been discovered.3 Hence modern methods to treat infectious microbes are to modify existing antibiotics. These modifications seek to improve activity, lessen sensitivity to resistance, and be less toxic.
In fact, the mechanism of these antibiotics is to target in microbes related translational machinery of the microorganisms (converting DNA/RNA information to protein), cell wall biosynthesis, DNA/RNA metabolism, and few other cellular processes. The mechanisms of resistance by the microbes include efflux pumps to pump out the antibiotics and enzymes that degrade the active component of the antibiotic.3
Moreover, the resistance to antibiotics occurs due to many reasons. One is lack of compliance to treatment regimens. People do not stick to the antibiotic treatment for the full duration such as the six month long time frame for TB treatment. Due to this lack of compliance the surviving bacteria pass on their resistance to subsequent bacteria. The antibiotic treatment should be thorough to completely kill all the bacteria.
Also, incorrectly prescribing antibiotics as sometimes done in agriculture contributes to resistance. Almost 80% of antibiotics sold in the U.S. are used in animals.2 These antibiotics are ingested by humans when they consume food. This transfer leads to only the resistant bacteria being consumed by humans since the bacteria susceptible to antibiotics are destroyed.
Another one of the challenges to the discovery of new antibiotics is that many large pharmaceutical companies do not think they will see a return on the millions of dollars invested on the research and development of new antibiotics. In addition, 99% of bacteria that are a potential source of new antibiotics cannot be cultured in the laboratory environment.4 Therefore, these obstacles are a direct hindrance to advances in discovery.
In conclusion, this is an arms race between humans and microorganisms throughout millennia. Eventually the pathogens acquire resistance and become “superbugs” even to the novel antibiotics. This is a crisis and humans are constantly trying to stay a step ahead of the microbes. So far this battle has proved beneficial because people in the U.S. in 1920 were expected to live to 56.4 years old and now the lifespan is nearly 80 years.2