The worldwide spread ofmultidrug-resistant (MDR) pathogenicbacteria has becomean urgent threat to human and animalhealth. More than two million people inthe United States become infected withantibiotic-resistant bacteria each year, andmore than 23,000 of them will die fromtheir infections. In 2015, approximately480,000 cases of MDR tuberculosisoccurred worldwide and another 100,000cases were resistant to at least one antibiotic.In the United States, cases of drugresistantenterobacteriaceae infectionsincreased three-fold between 2001 and2012. In 2016, a woman in Nevada died ofa Klebsiella pneumoniae infection caused bya strain that was resistant to 26 differentantibiotics, including colistin, which is consideredthe “last resort” antibiotic.One factor leading to the spread ofMDR bacteria is the selective pressurebrought about by repeated exposure toantibiotics. Worldwide, livestock consume used as feed supplements. The routineuse of antibiotics in livestock feed and theoveruse of human antibiotic prescriptionsare thought to be the most significant contributorsto the spread of MDR bacteria.A second factor leading to the new“post-antibiotic era” is the reductionin antibiotic drug development bypharmaceutical companies. Economicissues are significant. Drug companiesspend hundreds of millions of dollars todevelop and test a new drug. However,they receive less profit from antibioticsthan from more expensive drugs such aschemotherapies or diabetes drugs.Several alternative approaches arein development and early clinical trials.One very unique approach is the use oftherapeutic bacteriophages (phages).Phages have been used to treat bacterialinfections since the early 1900s, especiallyin Europe, but were abandoned inthe mid-twentieth century after the introductionof antibiotics. Researchers arereturning to phage, using modern moleculartools to modify phage and phagederivedproducts for use as antibacterialdrugs. No phage or phage products areyet approved for human therapies in theUnited States or Europe; however, severalphage preparations, targeted at pathogenssuch as Listeria, are approved for topicaluse on fresh and prepared foods, and atleast one phage therapy is in clinical trials.Although scientific and regulatorychallenges must still be overcome, we maybe on the verge of the Age of the Phage. Take time, individually or in groups,to consider the following questions.Investigate the references dealingwith the technical and ethical challenges ofcombating drug-resistant bacteria. Question: Two significant reasons for the spreadof MDR bacteria are the overuse ofagricultural antibiotics and the reluctanceof pharmaceutical companiesto develop new antibiotics. Discussthe ethical concerns surroundedthese two situations. For example,how do we balance our need forboth abundant food and infectioncontrol? Also, how can we resolve theethical disconnect between privatesectorprofits and the public good?
Genetic Recombination
Recombination is crucial to this process because it allows genes to be reassorted into diverse combinations. Genetic recombination is the process of combining genetic components from two different origins into a single unit. In prokaryotes, genetic recombination takes place by the unilateral transfer of deoxyribonucleic acid. It includes transduction, transformation, and conjugation. The genetic exchange occurring between homologous deoxyribonucleic acid sequences (DNA) from two different sources is termed general recombination. For this to happen, an identical sequence of the two recombining molecules is required. The process of genetic exchange which occurs in eukaryotes during sexual reproduction such as meiosis is an example of this type of genetic recombination.
Microbial Genetics
Genes are the functional units of heredity. They transfer characteristic information from parents to the offspring.
The worldwide spread of
multidrug-resistant (MDR) pathogenic
bacteria has become
an urgent threat to human and animal
health. More than two million people in
the United States become infected with
antibiotic-resistant bacteria each year, and
more than 23,000 of them will die from
their infections. In 2015, approximately
480,000 cases of MDR tuberculosis
occurred worldwide and another 100,000
cases were resistant to at least one antibiotic.
In the United States, cases of drugresistant
enterobacteriaceae infections
increased three-fold between 2001 and
2012. In 2016, a woman in Nevada died of
a Klebsiella pneumoniae infection caused by
a strain that was resistant to 26 different
antibiotics, including colistin, which is considered
the “last resort” antibiotic.
One factor leading to the spread of
MDR bacteria is the selective pressure
brought about by repeated exposure to
antibiotics. Worldwide, livestock consume used as feed supplements. The routine
use of antibiotics in livestock feed and the
overuse of human antibiotic prescriptions
are thought to be the most significant contributors
to the spread of MDR bacteria.
A second factor leading to the new
“post-antibiotic era” is the reduction
in antibiotic drug development by
pharmaceutical companies. Economic
issues are significant. Drug companies
spend hundreds of millions of dollars to
develop and test a new drug. However,
they receive less profit from antibiotics
than from more expensive drugs such as
chemotherapies or diabetes drugs.
Several alternative approaches are
in development and early clinical trials.
One very unique approach is the use of
therapeutic bacteriophages (phages).
Phages have been used to treat bacterial
infections since the early 1900s, especially
in Europe, but were abandoned in
the mid-twentieth century after the introduction
of antibiotics. Researchers are
returning to phage, using modern molecular
tools to modify phage and phagederived
products for use as antibacterial
drugs. No phage or phage products are
yet approved for human therapies in the
United States or Europe; however, several
phage preparations, targeted at pathogens
such as Listeria, are approved for topical
use on fresh and prepared foods, and at
least one phage therapy is in clinical trials.
Although scientific and regulatory
challenges must still be overcome, we may
be on the verge of the Age of the Phage.
Take time, individually or in groups,
to consider the following questions.
Investigate the references dealing
with the technical and ethical challenges of
combating drug-resistant bacteria.
Question: Two significant reasons for the spread
of MDR bacteria are the overuse of
agricultural antibiotics and the reluctance
of pharmaceutical companies
to develop new antibiotics. Discuss
the ethical concerns surrounded
these two situations. For example,
how do we balance our need for
both abundant food and infection
control? Also, how can we resolve the
ethical disconnect between privatesector
profits and the public good?
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