Control of Microorganisms

<p>Reducing microbial population to safe levels (A)</p> Signup and view all the answers

<p>Chemical use to kill microorganisms within host tissues (A)</p> Signup and view all the answers

<p>A reduction of 99.9% of the initial population (B)</p> Signup and view all the answers

<p>They are inactive but can potentially recover (A)</p> Signup and view all the answers

<p>Color of the environment (C)</p> Signup and view all the answers

<p>Higher temperatures kill more microbes effectively (C)</p> Signup and view all the answers

<p>Time taken to kill 90% of a microbial population (C)</p> Signup and view all the answers

<p>When they are exposed to low concentrations of antimicrobials (B)</p> Signup and view all the answers

<p>Increases the time needed to kill (A)</p> Signup and view all the answers

<p>They recover and can cause infection (A)</p> Signup and view all the answers

<p>Penicillins (B)</p> Signup and view all the answers

<p>b-lactam ring (A)</p> Signup and view all the answers

<p>Growing bacteria (A)</p> Signup and view all the answers

<p>Catalyze transpeptidation (C)</p> Signup and view all the answers

<p>They include penicillin V and G. (C)</p> Signup and view all the answers

<p>Produce b-lactamase (D)</p> Signup and view all the answers

<p>Fluoroquinolones (A)</p> Signup and view all the answers

<p>Enhancing cell metabolism (D)</p> Signup and view all the answers

<p>It does not penetrate glass or dirt films. (B)</p> Signup and view all the answers

<p>Carbolic acid (phenol) (D)</p> Signup and view all the answers

<p>70% (D)</p> Signup and view all the answers

<p>They can cause skin irritation and have a disagreeable odor. (D)</p> Signup and view all the answers

<p>It can produce carcinogenic compounds when interacting with organic matter. (D)</p> Signup and view all the answers

<p>Alcohols denature proteins and dissolve membrane lipids. (B)</p> Signup and view all the answers

<p>As a skin antiseptic during surgery preparation. (D)</p> Signup and view all the answers

<p>It may lead to the development of antibiotic-resistant bacteria. (C)</p> Signup and view all the answers

<p>They can be effective but often have safety concerns. (A)</p> Signup and view all the answers

<p>Phenolic compounds can remain active for longer periods. (D)</p> Signup and view all the answers

<p>Violent allergic response (C)</p> Signup and view all the answers

<p>Resistance can be transmitted to other bacteria (D)</p> Signup and view all the answers

<p>Drug efflux pumps (B)</p> Signup and view all the answers

<p>By binding to the bacterial ribosome (A)</p> Signup and view all the answers

<p>Production of b-lactamases (D)</p> Signup and view all the answers

<p>Spontaneous mutations (A)</p> Signup and view all the answers

<p>They can bypass drug inhibition by using different mechanisms (C)</p> Signup and view all the answers

<p>They block steps in protein synthesis (C)</p> Signup and view all the answers

<p>It is a target for sulfonamides in bacteria. (A)</p> Signup and view all the answers

<p>Horizontal gene transfer. (B)</p> Signup and view all the answers

<p>Bacterial chromosomes, plasmids, transposons, and phages. (C)</p> Signup and view all the answers

<p>Overuse and misuse of antibiotics. (B)</p> Signup and view all the answers

<p>Resistance to multiple types of antibiotics. (C)</p> Signup and view all the answers

<p>Overuse of antibiotics. (D)</p> Signup and view all the answers

<p>To protect themselves from their own antibiotics. (B)</p> Signup and view all the answers

<p>It drives the emergence of antibiotic resistance. (C)</p> Signup and view all the answers

Using chemicals (antiseptics) on body surfaces to destroy or prevent pathogens.

Reducing microbial numbers to a level considered safe.

Eliminating pathogens, but not bacterial spores, usually from non-living things.

Completely removing or destroying all living microorganisms.

A measure of how much a microbial population is decreased. 1 log reduction = 90% kill rate, 3 log reduction = 99.9% kill.

The time required to kill 90% of a microbial population.

Viable but non-culturable (VBNC) cells that are difficult to kill.

Larger populations take longer to kill with antimicrobials compared to smaller populations.

Microbial sensitivity to antimicrobials varies, some cells may be resistant.

Higher concentrations of antimicrobial agents lead to faster killing.

Longer exposure to the antimicrobial agent leads to more effective killing.

Cells in biofilms are resistant to many antimicrobials due to protective layers.

Higher temperatures increase the rate of microbial death.

UV light with a wavelength of 260 nanometers is most effective at killing bacteria. This is because DNA absorbs UV light at this wavelength, leading to damage.

UV radiation forms thymine dimers in DNA, preventing DNA replication and transcription. This disrupts the bacteria's ability to function and reproduce.

UV radiation can only sterilize surfaces and cannot penetrate materials like glass, water, or dirt films. This limits its usefulness for disinfection.

Joseph Lister, in 1867, was the first to use carbolic acid (phenol) to disinfect wounds and patients, marking a significant step in controlling infections.

A good disinfectant should be effective against a wide range of microbes at low concentrations, work in the presence of organic matter, and be stable in storage.

Excessive use of antiseptics can lead to the development of resistant microbes, including bacteria that are resistant to antibiotics.

Phenolics are widely used as disinfectants in labs and hospitals. They are effective against tuberculosis, work in the presence of organic matter, and have a long lifespan.

Phenolics disrupt cell membranes and denature proteins, leading to bacterial death. Examples include triclosan.

Alcohols, like ethanol and isopropanol, are effective because they denature proteins and dissolve cell membrane lipids.

Alcohol solutions are most effective when diluted to 70% with water. This allows the alcohol to penetrate cell membranes better and to remain active for a longer time.

Antibiotics target essential cellular processes in bacteria, often aiming for molecules both bacteria and humans have. These processes include cell wall synthesis, protein synthesis, nucleic acid synthesis, and metabolism.

Some antibiotics, like penicillins, interfere with the formation of a strong bacterial cell wall. This leads to weakened bacteria that can easily lyse (break open).

Penicillins are a major class of antibiotics that have a crucial part called the beta-lactam ring. This ring is essential for their ability to block bacterial cell wall formation.

Some bacteria have developed resistance to penicillins. They produce an enzyme called beta-lactamase, which breaks down the beta-lactam ring of penicillins, making them ineffective.

Penicillins block the enzyme that links together the chains of peptidoglycan, the building blocks of bacterial cell walls. This process is called transpeptidation.

Penicillins have different ranges of effectiveness. Some, like penicillin V and G, are narrow-spectrum, effective against limited types of bacteria. Others are broader-spectrum, targeting a wider array of bacteria.

Peptidoglycan, the main component of bacterial cell walls, is made of sugar strands (glycans) linked together by amino acids. These amino acid connections are called crosslinks.

Penicillins only work on bacteria that are actively dividing and building new cell walls. They target this specific process.

The spread of resistance to b-lactam antibiotics is a major concern as it can lead to treatment failures and increased healthcare costs.

Aminoglycosides bind to the bacterial ribosome's 30S subunit, interfering with protein synthesis and causing misreading of the messenger RNA.

Antibiotic resistance is the ability of bacteria to survive and multiply in the presence of antibiotics, making infections harder to treat.

Phenotypic drug resistance occurs when bacteria in certain environments, like abscesses or biofilms, grow slowly and become resistant to antibiotics.

Once resistance emerges in a bacterial population, it can spread to other bacteria, making the problem more widespread.

Bacteria develop resistance through mechanisms like modifying the target enzyme, inactivating the antibiotic, using efflux pumps, and altering metabolic pathways.

B-lactamase is an enzyme produced by bacteria that degrades b-lactam antibiotics, such as penicillin, rendering them ineffective.

Antibiotic resistance is a major global health threat as it makes common infections difficult to treat, leading to increased healthcare costs and mortality rates.

Bacteria develop resistance to sulfonamides by acquiring genes for dihydropteroate synthase (DHPS) variants that are not inhibited by the drugs.

Dihydropteroate synthase (DHPS) is an enzyme essential for bacterial folate synthesis. Sulfonamides inhibit this enzyme, disrupting bacterial growth.

The transfer of genetic material (like antibiotic resistance genes) between bacteria through mechanisms like conjugation, transduction, or transformation.

Antibiotic resistance genes exist naturally in bacteria, primarily in antibiotic-producing microbes, to protect them from their own antibiotics.

DNA segments capable of moving within and between genomes, such as plasmids, transposons and phages. They can carry antibiotic resistance genes.

A bacterial strain that developed resistance to methicillin, a powerful antibiotic used to treat Staphylococcus aureus infections.

MRSA strains that have evolved resistance to vancomycin, a potent last-resort antibiotic, making it highly dangerous.

Excessive use of antibiotics increases the selective pressure for resistant bacteria to thrive, driving the development of antibiotic resistance.