module 13


  1. Explain the difference between disinfection and sterilization.

Disinfection: Killing or inactivating microbes that cause disease

Sterilazation: Destroying all live microbes, spores and viruses


  1. Explain the difference between a disinfectant and antiseptic.

Disinfectant: Can be used on inanimate objects and surfaces but it is too toxic to the body

Antiseptic: Can be used on living body and tissues (e.g. wound)


  1. Name at least three chemical and physical disinfection/sterilization methods and note whether they disinfect or sterilize objects. 

Physical methods:

  • heat/sterilization: autoclaving

  • Heat: pasteurization, dry heat(oven), boiling, dehydration

  • Low temp control: refrigeration

Chemical methods:

  • 70% alchol: handsaitzier, skin antiseptic

  • Halogens: chlorine (pool, swimming), bromine, iodine (topical wounds)

  • Hydrogen peroxide: wound treamtment

  1. Briefly summarize the history of penicillin and sulfa drugs.

  • Alexander Fleming identified mold Penicillium excreting compound that was toxic to Staphylococcus

  • Penicillin became the first antibiotic used in 1941

  • Didn’t become a prescription drug until the mid-1950’s

  • (sulfa) drugs were the first “wonder” drugs

  • Considered antimicrobials, not antibiotics, because they are synthetic

  • Saved millions of lives in WWII

  1. Describe each of the following characteristics of antimicrobial medications:

  • Selective toxicity - Cause greater harm to microbes than their host

  • Interfere with essential structures or properties common in microbes but not in human cells

  • Toxicity is relative and expressed as therapeutic index (TI = TD/ED)

  • Antimicrobial action - Bacteriostatic vs. bactericidal

  • Spectrum of activity - Broad-spectrum vs. narrow spectrum

  • Effects of combinations - Antagonistic - interfere with each other

  • Synergistic - one medication enhances another

  • Additive - medications neither antagonistic or synergistic

  • Tissue distribution, metabolism and excretion - Antimicrobials differ in behavior in body

  • Blood-brain barrier

  • pH

  • Half-life

  • Adverse Effects -  Allergic reactions

  • Toxic effects

  • Dysbiosis of normal flora

  • Resistance to antimicrobials - certain bacteria have innate or intrinsic resistance

  • Bacteria may develop acquired resistance



  1. Explain why a physician may choose a broad-spectrum antibiotic over a narrow spectrum of antibiotics. What is one of the drawbacks of using a broad-spectrum antibiotic?

  • They can disrupt the natural gut flora, increasing the risk of superinfections and potentially leading to antibiotic resistance.

  1. Fill in the following chart for the five classes of antibiotics. Also be sure that you know the structure of the cell wall synthesis inhibitors. 


Mechanism

Spectrum of Activity

Limitations

Examples

Cell Wall Synthesis Inhibitors

inhibit enzymes that catalyze formation of peptide bridges between strands of

only effective against actively growing cells, usually more effective in Gram+ bacteria

Methicillin, Ampicillin, Vancomycin, Bacitracin

Protein Synthesis Inhibitors

Exploits differences between prokaryotic (70S) and eukaryotic (80S) ribosomes

Block translation

Gram + and Gram -

Some toxic due to mitochondria also having 70S ribosomes

Tetracyclines, macrolides, streptogramins, aminoglycosides

Nucleic Acid Synthesis Inhibitors

  Block DNA replication (gyrase)

     Block RNA polymerase (transcription)

Both major classes bactericidal and    

    broad spectrum

Development of resistance

Fluoroquinolones, Rifamycins

Metabolic Pathway Interference

Antimetabolites competitively bind with enzymes (molecular mimicry) rendering them inactive

Bacteriostatic and broad spectrum

Sulfa drugs (sulfonamides), trimethoprim

Cell Membrane Interference

Damage bacterial membranes → causes cells to leak, leading to death

Topical applications only                      due to toxicity

Narrow spectrum

Daptomycin, Polymyxin B





  1. Explain why antibiotic resistance is inevitable in bacterial species, but why we are seeing it happening at an increasing rate. 

  • The increasing rate of antibiotic resistance is driven by factors like the overuse and misuse of antibiotics, which create a selective pressure that favors resistant bacteria.

  • germs (bacteria, fungi) develop the ability to overcome the effect of antibiotics designed to kill them

  1. Briefly summarize the impact that antibiotics have on healthcare and the detrimental effects of the rise in antibiotic resistance. 

  • makes infections harder to treat, leading to longer hospital stays, more costly treatments, and potentially increased mortality

  1. Summarize the five mechanisms of antibiotic resistance.

  • Enzymatic Inactivation

  • Alter antibiotic uptake

    • Membrane pump

    • Decrease membrane permeability

  • Modify target of antibiotic

  • Develop alternate metabolic pathway


  1. How can bacterial cells acquire new antibiotic resistance capabilities?

  • Plasmids; circles of DNA that move between cells

  • Phages: viruses attack germs and and carry DNA from germ to germ

  • Transposons 

  1. Explain the process that happens when people misuse antibiotics and how it leads to the spread of resistant bacteria.

  • When susceptible bacteria are killed by antibiotics, resistant bacteria survive and multiply, passing on their resistance to future generations.

  1. Summarize the three main factors that are driving the rise of antibiotic resistance.

  • Overuse

  • Inappropriate prescribing

  • Extensive agricultural use

  1. Summarize how antibiotic resistance can spread to the community setting through agriculture and the healthcare setting. 

  • Purchasing online

  • Lack of regulation

  • 80% of antibiotics sold in the U.S. are used in animals to promote growth and prevent infections

  • 90% of antibiotics given to livestock are excreted then widely dispersed through fertilizer, groundwater, and surface runoff

  1. What strategies can healthcare workers employ to prevent the spread of antibiotic resistance?

  • Tracking and improving approatie antibiotic use

  • Stopping the spread of resistant germs

  1. Why can’t we rely on the production of new antibiotics to solve the problem of antibiotic resistance?

  • Financial and regulatory hurdles: Developing an antibiotic is extremely costly and often takes ten years or more. Each new formulation must undergo rigorous testing for both activity and patient safety, and only a minority of candidates will successfully navigate the entire drug development process.

  1. Describe the following alternatives to antibiotics that are being developed:

  • Vaccines - Vaccines can provide long-lasting protection against bacterial infections by stimulating the immune system to produce antibodies

  • Antibodies - Antibodies, especially monoclonal antibodies (mAbs), can neutralize bacterial toxins or directly target bacterial surfaces to kill bacteria. 

  • Bacteriophages- Bacteriophages are viruses that specifically infect and kill bacteria. 

  • FMT - FMT involves transferring a healthy donor's gut microbiota into a recipient to restore gut balance.

  • Other alternative agents