Plasmids play an important role in transmission
Dynamics of pAR145 during range expansion
The initial study quantified the dynamics of pAR145, a plasmid encoding antibiotic resistance, during range expansion in the absence of chloramphenicol, serving as a positive selection for pAR145. The researchers observed that the potential donor and recipient cells of pAR145 rapidly separate during range expansion, resulting in a subdivision spatial pattern with reduced admixture. The appearance of cyan regions indicates extensive pAR145 transfer and conjugation formation in the early stages of range expansion. However, both conjugate donors and pAR145 were gradually displaced by plasmid-free cells, leading to a reduction in pAR145 loading. This depletion is attributed to the competitive advantage of plasmid-free cells and the consequent cost associated with carrying pAR145 in the absence of chloramphenicol.
Timing of antibiotic use and metabolite proliferation
Based on the rapid depletion of pAR145 load during range expansion, the researchers hypothesized that the timing of chloramphenicol administration, which provides positive selection for pAR145, would determine proliferation next of the transitional cells. Surprisingly, they discovered a unidirectional relationship between the frequency of synaptic cells at the extended boundary and the duration of antibiotic use. The maximum frequency of transitions occurred at the time of intermediate management, contrary to their initial expectation of a monotonous downtrend. In addition, the extent of range expansion during chloramphenicol treatment also followed a unimodal pattern, reaching a maximum at the time of intermediate administration. These findings indicate that the timing of antibiotic administration plays an important role in determining transconjugated proliferation and community expansion.
Effect of duration of antibiotic use on the spread of plasmid
Further analysis revealed that the degree of spatial miscibility, which affects plasmid transmission, also exhibits a unidirectional relationship with duration of antibiotic use. At the time of previous administration, spatial patterns included contiguous regions including pAR145 donor and conjugate cells, indicating efficient plasmid transfer. In contrast, at later administration times, the spatial patterns became discontinuous and consisted of isolated bubble-like structures, suggesting limited plasmid transmission due to depletion of the plasmids. cells carrying pAR145. In addition, the proportion of conjugated pAR145 donor cells at the expansion boundary saturated at later administration time points, suggesting that the number of conjugated transitional cells did not increase monotonically.
Local proliferation of conjugated cells
To understand whether the increased number of synaptic transition cells at the time of mediation was due to enhanced transfer events or individual cell proliferation, the researchers performed computational simulations. . Simulations demonstrated that better proliferation of individual transitional cells, rather than an increase in transfer events, contributed to the higher frequency of transitional cells intermediate management times. This finding highlights the importance of local proliferation in promoting the spread of plasmids encoding antibiotic resistance in microbial communities.
Authority to solve :
- Timing of antibiotic administration determines the spread of plasmid-encoded antibiotic resistance during bacterial range expansion – (https:pubmed.ncbi.nlm.nih.gov/37316482/)