Scientists discovered the phenomenon during a lab experiment involving two kinds of Staphylococci bacteria. The first kind is marked bright green by a fluorescent protein; it expressed a resistance gene for the antibiotic chloramphenicol. The brightly labeled bacteria is placed alongside Streptococcus pneumoniae, bacteria without the resistance gene.
When placed in a medium containing the antibiotic, the green cells begin to proliferate while the black cells stand pat. After a time, the black cells too begin to divide and grow, outpacing the green cells.
"The resistant cells take up the chloramphenicol and deactivate it," Robin Sorg, a microbiologist at the University of Groningen, said in a news release. "At a certain point, the concentration in the growth medium drops below a critical level and the non-resistant cells start growing."
Researchers have previously imaged cellular secretions reactivating antibiotics, but the newly observed phenomenon occurs inside the cells -- a first.
The findings -- detailed in the journal PLOS Biology -- further illuminate the problem of antibiotic resistance.
"It is complicated," Sorg explained. "We know that antibiotic usage results in selection for resistance. However, we do not fully understand the processes, nor why antibiotic resistance can develop so fast. Single cell studies like ours help to fill in some of these details."
Scientists say their research is a reminder of the importance of caution, and perhaps a more conservative approach, when considering antibiotic use.
"We know that we should use these drugs with discretion, but we may need to be even more careful than we thought," Sorg concluded.