Staphylococcus aureus is naturally susceptible to virtually every antibiotic that has ever been developed. Resistance is often
acquired by horizontal transfer to genes from outside sources
, although chromosomal mutation and antibiotic selection are also important.
Why is the evolution of antibiotic resistance in bacteria happening so quickly?
Bacteria can evolve quickly
because they reproduce at a fast rate
. Mutations in the DNA of bacteria can produce new characteristics. A random mutation might cause some bacteria to become resistant to certain antibiotics , such as penicillin.
Which of the following contributes to the evolution of antibiotic resistant bacteria?
Antibiotic resistance is a consequence of evolution
via natural selection
. The antibiotic action is an environmental pressure; those bacteria which have a mutation allowing them to survive will live on to reproduce. They will then pass this trait to their offspring, which will be a fully resistant generation.
Which of the following is an observation or inference on which natural selection is based quizlet?
Which of the following is an observation or inference on which natural selection is based?
Species produce more offspring than the environment can support.
How did Staphylococcus aureus become resistant?
Staphylococcus aureus can become drug-resistant by
genetic mutations that alter the target DNA gyrase or reduce outer membrane proteins
, thereby reducing drug accumulation (Kime et al., 2019; Yang et al., 2019).
How does Staphylococcus aureus become resistant to methicillin?
S. aureus can become resistant to methicillin and other β-lactam antibiotics through
the expression of a foreign PBP, PBP2a
, that is resistant to the action of methicillin but which can perform the functions of the host PBPs.
How does mutation cause antibiotic resistance?
Mutations can provide resistance to antibiotics
If we were to treat the bacterial population with that specific antibiotic,
only the resistant bacteria will be able to multiply; the antibiotic selects for them
. These bacteria can now increase in numbers and the end result is a population of mainly resistant bacteria.
How fast do bacteria become resistant to antibiotics?
“The experiment shows just how easy it is for bacteria to evolve resistance – how quickly evolution can occur.
In just 11 days
, resistance levels increased by over 1000-fold,” said Professor Kishony.
What causes antibiotic resistance?
The main cause of antibiotic resistance is
antibiotic use
. When we use antibiotics, some bacteria die but resistant bacteria can survive and even multiply. The overuse of antibiotics makes resistant bacteria more common. The more we use antibiotics, the more chances bacteria have to become resistant to them.
How can bacteria become resistant to cephalosporins?
Bacterial resistance to /3-lactam antibiotics is due to
reduced permeation of the drugs through the outer cell membrane
, inac- tivation of the compounds by /3-lactamases, and the inability of the compounds to bind to target penicillin-binding proteins (PBPs) that have been altered.
Which environment stimulates evolution of drug resistant pathogens?
humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin. convergent evolution. What environment stimulates evolution of drug-resistant pathogens?
Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial
.
Which of the following is not an observation or inference on which natural selection based?
Natural selection is the process of the adaptation of an organism to its surrounding environment through selectively reproducing changes in their genotype or genetic constitution.
Poorly adapted individuals never produce offsprings
is not an observation of Darwin’s natural selection.
Which of the following would not contribute to bacteria developing resistance to antibiotics?
Antibiotic resistance in children and older adults are of particular concern due to high rates of antibiotic use. Once a particular bacterium becomes resistant to an antibiotic, treating that infection becomes more difficult and in some cases,
medically impossible
. Untreated, bacterial infections can spread rapidly.
Which piece of evidence most strongly supports the common origin of life from an ancestor?
Like anatomical structures, the structures of the molecules of life reflect descent with modification. Evidence of a common ancestor for all of life is reflected in
the universality of DNA as the genetic material and in the near universality of the genetic code and the machinery of DNA replication and expression
.
How did Staphylococcus aureus become resistant to vancomycin?
Strains of hVISA and vancomycin-intermediate Staphylococcus aureus (VISA) do not have resistant genes found in Enterococcus and the proposed mechanisms of resistance include the
sequential mutations resulting in a thicker cell wall and the synthesis of excess amounts of D-ala-D-ala residues
.
Why do most strains of the human pathogen Staphylococcus aureus be resistant to action of penicillin?
PBP2a substitutes for the other PBPs and, because
of its low affinity for all
β-lactam antibiotics, enables staphylococci to survive exposure to high concentrations of these agents. Thus, resistance to methicillin confers resistance to all β-lactam agents, including cephalosporins.
How does Staphylococcus aureus start?
These bacteria are spread by having
direct contact with an infected person
, by using a contaminated object, or by inhaling infected droplets dispersed by sneezing or coughing. Skin infections are common, but the bacteria can spread through the bloodstream and infect distant organs.
What does it mean for a strain of bacteria to be sensitive to an antibiotic?
Susceptible (s): A bacterial strain is said to be susceptible to a given antibiotic when it is inhibited in vitro by a concentration of this drug that is associated with
a high likelihood of therapeutic success
.
What major class of antibiotics is effective in the treatment of methicillin resistant Staphylococcus aureus?
Vancomycin or daptomycin
are the agents of choice for treatment of invasive MRSA infections [1].
How does methicillin resistant Staphylococcus aureus commonly manifest and evolve?
MRSA often
begins as a small skin infection
, but can spread quickly and if left untreated, can progress into a more serious condition that can affect other parts of the body. The CDC reports that transmission occurs most frequently by direct skin-to-skin contact.
How does salmonella become resistant to antibiotics?
There are several reasons to conclude that antibiotic-resistance among human Salmonella isolates are the result of the use of antimicrobial agents in food animal production: (1) tracebacks from foodborne disease outbreaks have shown food animals as the ultimate source of infection (outbreak refs), (2)
antimicrobial
…
Which of the following plasmid provides resistance against antibiotics in bacteria?
Plasmids often carry multiple antibiotic resistance genes, contributing to the spread of multidrug-resistance (MDR). Antibiotic resistance mediated by
MDR plasmids
severely limits the treatment options for the infections caused by Gram-negative bacteria, especially family Enterobacteriaceae.
What are the main mechanisms of antimicrobial resistance?
The main mechanisms of resistance are:
limiting uptake of a drug, modification of a drug target, inactivation of a drug, and active efflux of a drug
. These mechanisms may be native to the microorganisms, or acquired from other microorganisms.
What are the five mechanisms of antimicrobial resistance?
- Lack of entry; Decreased cell permeability.
- Greater exit; Active efflux.
- Enzymatic inactivation of the antibiotic.
- Altered target; Modification of drug receptor site.
- Synthesis of resistant metabolic pathway.
How do bacteria become multidrug resistant?
Multidrug resistance in bacteria occurs by
the accumulation, on resistance (R) plasmids or transposons, of genes
, with each coding for resistance to a specific agent, and/or by the action of multidrug efflux pumps, each of which can pump out more than one drug type.
How the bacteria develop resistance against the penicillins and cephalosporins?
The most important mechanism of resistance to the penicillins and cephalosporins is
antibiotic hydrolysis mediated by the bacterial enzyme beta-lactamase
. The expression of chromosomal beta-lactamase can either be induced or stably depressed by exposure to beta-lactam drugs.
Why is it so difficult to prevent the spread of drug resistance in bacteria?
Antibiotic resistance occurs when bacteria develop defenses against the antibiotics designed to kill them. This renders
the drugs useless against the new resistant strains
, allowing resistance to grow and spread to other germs, creating drug-resistant infections that can be difficult to treat.
How does bacteria become resistant to antibiotics GCSE?
Bacteria can evolve quickly because they reproduce at a fast rate. Mutations in the DNA of bacteria can produce new characteristics.
A random mutation
might cause some bacteria to become resistant to certain antibiotics , such as penicillin.
What factors associated with the evolutionary biology of bacteria facilitate the evolution of resistance to antibiotics?
The three main processes shaping the evolutionary ecology of antibiotic resistance (AbR) involve
the emergence, invasion and occupation by antibiotic-resistant genes of significant environments for human health
.
Why are enterococci resistant to cephalosporins?
Intrinsically resistant to many β-lactams (e.g., cephalosporins)
due to inner cell wall penicillin-binding proteins
. Resistant to TMP/SMX as organism uses exogenous folate to overcome anti-folate synthesis mechanism.
What has caused the development of drug resistant microbes?
Misuse and overuse of antimicrobials
are the main drivers in the development of drug-resistant pathogens. Lack of clean water and sanitation and inadequate infection prevention and control promotes the spread of microbes, some of which can be resistant to antimicrobial treatment.
Which is the best reason why some insects are resistant to pesticides?
Upon exposure to insecticides,
insects that do not carry the resistance genes die
, thus allowing the individuals with the resistance genes to survive and reproduce, creating more resistant insects.
Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago?
Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago? …
rRNA mutates rapidly
. rRNA is traditionally the nucleic acid chosen for recent comparisons. DNA coding for rRNA changes relatively slowly.
What is the only evolutionary mechanism that consistently leads to adaptive evolution?
Natural selection
is the only evolutionary mechanism that consistently leads to adaptive evolution. Sexual selection may lead to pronounced secondary differences between the sexes.
Are changes to an organism’s physical environment likely to result in an evolutionary change?
Change in an organism’s environment forces the
organism to adapt to fit the new environment
, eventually causing it to evolve into a new species. … Organisms become isolated as a result of environmental change. The cause of isolation can be gradual, like when mountains or deserts form, or continents split apart.
