The death of a woman in Nevada reported on January 13 has set off alarm bells in the global medical community. The woman died of a incurable infections and was, according to the Center for Disease Control in the United States, resistant to all 26 antibiotics available in the country to treat infection.
The infection was caused by so-called “superbugs”, pathogenic bacteria that is resistant to a range of antibiotics. There have been superbug deaths in the US, India and other parts of the world before but the Nevada woman’s death is different is because the infection was detected early and but even drugs normally used as the last line of defense against bacterial infection did not work. The woman was reported to have contracted the Klebsiella pneumonia infection after repeated hospitalisations in India for a broken thighbone about two years ago.
Researchers have been documenting how overuse and improper use of antibiotics spreads resistance among bacteria. But now, a new mechanism has been discovered that reveals how antibiotic resistance is more complicated than previously thought.
It turns out that bacteria that are normally susceptible to antibiotics can survive when enough resistant cells around express an antibiotic-deactivating factor, according to microbiologists from the University of Groningen.
In their paper published in PLOS Biology, the researchers explain their experiment of growing Staphylococci bacteria expressing a resistance gene for the antibiotic chloramphenicol next to Streptococcus pneumoniae bacteria that do not have the resistance gene. In a medium containing the antibiotic, the Staphylococci cells begin to grow and divide while the Streptococcus pneumoniae do not. But, after a while, even the Streptococcus pneumonia divide and even outgrow the drug-resistant Staphylococci. This is because the resistant cells take up the chloramphenicol and deactivate it. When the concentration of the antibiotic in the growth medium drops below a critical level , even non-resistant cells start growing.
The phenomenon can be seen in a short time-lapse video created by the research team in which the resistant Staphylococci bacteria show up as green and the non-resistant Streptococcus pneumonia bacteria are black.