Hungarian researchers describing pathogens resistant to antibiotics

Antibiotic resistance can be defined as the capability of microorganisms to become insensitive to the action of applied antibiotic. The mechanism is a consequence of natural selection during which random mutations in particular genes are responsible for microorganism’s resistance. In the presented work, Hungarian researchers have focused on the fact that evolution of antimicrobial resistance enhances resistance to other drugs. The laboratory evolution experiments on Escherichia coli bacteria have depicted that they can adjust very rapidly to a rising dosages of twelve different antibiotics that were applied. Understanding of such phenomenon may help in development of new anti-microbial drugs.

Microorganisms, including bacteria, fungi or parasites possess natural capability of rather fast adaptation to changing environment. When antibiotic is applied, some genetic changes may appear, which can eventually lead to the survival of the microbes. There are several biological ways in which this happens. The first one is simple selective pressure, meaning that in the presence of antimicrobial compound only bacteria with resistance genes survive, replicate and become dominant in the whole population. Another thing is the occurrence of mutations that in fast-replicating organisms can substantially facilitate the survival in the presence of drugs. The last cause is a gene transfer that occur within microbial populations, giving the resistance to more and more cells.

Apart from natural causes, the antimicrobial resistance to antibiotics is also a man’s fault. An inappropriate usage of antimicrobials is of great importance. However, even if used properly, antibiotic application results in selective pressure accelerating the occurrence of the resistance. Another problem is associated with extensive use of antibiotics in hospitals, where closed environment fosters the spread of the resistance. It is also suggested that application of antimicrobial compounds in agricultural feed also triggers it.

As the problem of antibiotic resistance is becoming more and more serious there is a need to decipher underlying mechanisms of this phenomenon. Hungarian researchers from Research Centre of the Hungarian Academy of Science aimed to provide insight into the basics of cross-resistance – a situation when bacteria accommodate to an antibiotic and become resistant to other antibiotics even though they were never encountered by them. In order to explore the whole process, the scientist performed parallel evolutionary experiments with Escherichia Coli to adapt to rising amounts of one of 12 antibiotics, and deduced a network of interactions taking place during cross-resistance.

The results of genetic analysis and genome engineering experiments enabled to draw several conclusions. First, it was revealed that bacterial exposure to a single antibiotic often results in multidrug resistance. Moreover, cross-resistance between two antibiotics is rather not dependent on whether they present synergistic effects when applied together. The researchers also concluded that the resistance evolution is in some way attained by the accumulation of genomic rearrangements and loss-of-function mutations.

The antimicrobial resistance has become a  global concern in recent years. Multidrug- resistant bacteria can escape from the action of antibiotics and are extremely difficult to eradicate, which is a threat for our ability to treat ubiquitous infectious disease. The effective treatment need to be elaborated basing on the results of such studies as presented by the Hungarian researchers.

Sources:

http://www.sciencedaily.com/articles/a/antibiotic_resistance.htm

http://www.who.int/mediacentre/factsheets/fs194/en/

http://www.niaid.nih.gov/topics/antimicrobialresistance/understanding/pages/causes.aspx

http://mta.hu/news_and_views/new-results-from-momentum-researchers-in-the-description-of-pathogens-resistant-to-antibiotics-134830/

Lázár, Viktória, et al. "Genome-wide analysis captures the determinants of the antibiotic cross-resistance interaction network." Nature communications 5 (2014).

Maciej Smolarz