There are "promiscuous plasmids," plasmids that can replicate in several different species of bacteria.Frequently these plasmids have transposons carrying antibiotic resistance.In a hospital that has an outbreak of a variety of bacteria carrying resistance to streptomycin, gentamicin, and penicillin how what is the best way to determine that this resistance was due to a shared plasmid?
A)Demonstrate that all the resistant bacteria have a plasmid and that these plasmids have an identical (or nearly identical) sequence..
B)Isolate plasmids from all resistant bacterial species and demonstrate that sensitive cells from these same species become resistant when this plasmid is transformed..Confirm that these are the same plasmids by sequencing.
C)Sequence the genomes of the resistant sspecies and demonstrate mutations in the same homologous genes..
D)Isolate any plasmids from one resitant species and transform a sensitive strain of the same bacterium to see if resistance occured in the transformants.

Question

Quizplus · Accepted Answer

Isolating plasmids from all resistant bacterial species and demonstrating that sensitive cells from these same species become resistant when this plasmid is transformed is the most direct and reliable method for determining that the resistance is due to a shared plasmid. Confirming that these are the same plasmids by sequencing would provide further evidence. Demonstration of plasmids and sequencing their identical (or nearly identical) sequence would not necessarily prove that they confer the resistance, as another characteristic (such as metabolic function or virulence) could be the function carried by the identical plasmids. Sequencing genomes of resistant species and determining mutations in the same genes is not as reliable since the resistance could be due to different mutations or different genes. Isolating plasmids from only one resistant species and transforming a sensitive strain of the same bacterium would not provide evidence about whether other species carry the same plasmid.

There Are "Promiscuous Plasmids," Plasmids That Can Replicate in Several