Another method of genetic transfer is transduction. It is the transfer of genetic information done by bacterial viruses, called bacteriophages. The phages bind onto a site on the bacteria's cell membrane and injects its DNA into the host cell. The DNA from the phage can do one of two things: The DNA could be non-infective and incorporate the genes it carries into the bacteria's own DNA or the virus could multiply and destroy the host cell. If the viral DNA with the resistance gene incorporates into the bacterial chromosome, the gene will pass to the bacteria's progeny when it reproduces. However, when the virus wants to multiply, the viral DNA could take pieces of the host's DNA. If the host carried the gene for antibiotic resistance, the new phages will inject its DNA along with the DNA containing the antibiotic resistant gene into another bacteria where the virus life-cycle cycles again As another means of transferring information can occur through transposons between the viral DNA and the bacterial DNA.
Transposition is a means of genetic transfer using transposons, which are even smaller pieces of DNA, to deliver genes including ones needed for antibiotic resistance. The transposon can jump off of plasmids and integrate itself into a new host's DNA or into a resident plasmid after conjugation. Thus, the genetic information carried by the transposon still lives even though the plasmid that transferred the information has died. Therefore, the transposons do not need to rely on a particular host cell to multiply and survive since it simply integrates itself into the bacteria's chromosome or into a plasmid that is already residing within.
The bacteria could also transform by taking in DNA through the cell membrane. The DNA could be extracted from one bacteria and incorporated into the DNA of another.
Antibiotics overuse/misuse has made the problem worse. Bacteria are constantly adapting to their environment. A new generation of microbes could come every 20 minutes, in comparison with a few years for larger animals, which helps to speed up the evolutionary process. Antibiotics used on healthy cows only helps the bacteria by increasing its exposure and thus allowing a greater chance for spontaneous mutation. Antibiotics are used on healthy animals so that they would be larger than if antibiotics were not used. When small amounts of antibiotics are given to cows all of their energy can go into getting larger rather than into fighting off disease. Then the bacteria who acquired the resistance gene could pass from the animal to humans who consume the beef.
Antibiotics also take the resistant bacteria's competition. When someone uses antibiotics to treat an infection, the drug kills off the susceptible bacteria leaving the resistant ones to flourish where they would ordinarily have to compete for space and nourishment in order to multiply.
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