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What is the major role that antibiotics plays in the world?
Increasing life expectancy
Why might antibiotics soon become useless?
Antibiotics are overprescribed and misused, and are used in farm animal feed.
What Presentation of nosocomial staphylococcus infections are the result of methicillin-resistant S. aureus (MRSA)?
60%-70%
How long did it take from 1940 when penicillin was introduced for the first resistant strain to appear in spain?
40 years
How do we decrease the amount of antibiotic resistant bacteria?
By controlling all antibiotics, which is nearly impossible.
What did ancient egyptians use to prevetn infections in wounds?
Apply moldy bread to the lesion.
Bones of ancient Nubian people were saturated with this antibiotic?
Tetracycline.
Whatn is the definition of an antibiotic?
A compound produced by one microbe that adversely affects other microbes.
Who in 1897, proposed that bacteria and molds engage in a perpetual battle fro survival?
Ernest duchesne
Who rediscovered penicillin in 1928?
Alexander Fleming
What mold was identified by Alexander Fleming?
Penicillium notatum
In the 1940s who purified Penicillin?
Howard Florey and Ernst Chain; strain was penicillin G.
Who discovered sulfa drugs (Prontosil dye), a synthetic drug?
Gerhard Domagk
How do sulfa drugs work?
They mimic PABA which is a precursor of a vitamin needed fro DNA synthesis. The compound is inactive until it is converted in the body into its active agent.
What are antimicrobials?
Anything theat kills microbes, organic or synthetic.
Who discovered the frug of the century, streptomycin, in the 50s or 60s that was easy to produce adn very effective?
Selman Waksman
What created streptomycin, also what type of abcteria creat similar antibiotics to streptomycin?
Streptomyces griseus, Actinomycete bacterium in the soil
What are the two criteria fro antibiotic to be effective?
The drug must affect the targeted organism and must not affect humans.
What are some example of physiology that antibiotic can target that do not affect humans?
peptidoglycan
Differences in ribosome structure
Biochemical pathways missing in humans
What are some of the side effects of antibiotics?
Allergic Response
What does Chloramphenicol interfere with?
RBC Development
Is it the first or second condition that most antibiotics fail?
The second
What is an antibiotic that is effective against many species (both Gram + and Gram -)?
Broad Spectrum
What is an antibiotic that is effective against specific organisms?
Narrow Spectrum
What antibiotic only works for Mycobacterium tuberculosis.
Isoniazid
What type of antibiotic kills targeted organisms immediately?
Bactericidal
What type of antibiotics prevent growth of Organism but cannot kill the organism? This antibiotic just weakens the bacteria so that the immune system can get rid of it.
Bacteriostatic
What factors must a clinician use to decide which antibiotic to prescribe?
The relative effetiveness of different antibiotics on the organism causing the infection
The average attainable tissue levels of each drug
Minimal inhibitory concentration (MIC)
What is MIC?
The lowest concentration that prevents growth, this vaies for different Bacteria.
What is MBC
Minimal bactericidal Concentration.; Also known as Minimal Lethal Concentration (MLC)
How do you determine the MBC?
Use the tubes that go after the MIC tube, which is the first tube that does not show growth. With the tubes grow them in a plate and determine which results in no growth at the least concentration of Antibiotic.
Consider an MIC result of 5 μg/ml of penicillin for bacterial strain A, 25 μg/ml for strain B, 15 μg/ml for strain C, and 20 μg/ml for strain D. Which bacterial strain can be interpreted as the most resistant to penicillin?
B
The following image is a result from Kirby-Bauer Disk Susceptibility test of Staphylococcus aureus against three antibiotics. What can be concluded from the result below.
Staphylococcus aureus is resistant to antibiotic A
Zone of inhibition (mm) | |||
Antibiotic | Resistant | Intermediate | Susceptible |
Amoxicillin | < 12 | 12 - 13 | > 13 |
Oxacillin | < 13 | 13 - 17 | > 17 |
Vancomycin | < 14 | 14 - 18 | > 18 |
Ampicillin | < 18 | 18 - 22 | > 22 |
Antibiotic | Zone of inhibition |
Amoxicillin | 14 mm |
Oxacillin | 16 mm |
Vancomycin | 18 mm |
Ampicillin | 22 mm |
The following results were obtained from a disk-diffusion test for microbial susceptibility to 4 antibiotics. MRSA was the test organism.
Based on the results above, which of the tested antibiotics should be used to kill the organism.
Amoxicillin
The best target for development of a new antibiotic against Mycobacterium species would be
mycolic acids.
What and where is Vancomycin derived?
It is a very large and is a glycopeptide produce by Streptomycete spp..
How does Vancomyscin inhibit cell wall synthesis?
It binds to D-Ala-D-Ala terminal and prevents the action of transglycolysases and transpeptidase. (prevents Peptide Bridge in Gram +)
Is Vancomycin work for Gram - ?
No, it does not cross the LPS outer membrane of Gram -.
Can Vancomycin be given as a pill?
No it must be given intravenously due to poor absorption from intestinal tract.
Due to resistant strains of bacteria, Penicillin has become ineffective. What bacteria does Natural Penicillin still effect?
Gram + Cocci and some gram - Cocci
Scientis have created Penicillinase-resistant strains of penicillian to preven inactivation by penicillinase enzymes in Natural Penicilin resistant bacteria. What form of Penicilllinase-Resistant penicillin is the following?
Methincilllin Penicillianse Resitant.
Scientist have created Penicillinase-resistant strains of Penicillin to prevent inactivation by penicillinase enzymes in Natural Penicillin resistant bacteria. What form of Penicillinase-resistant penicillin is the following?
Dicloxacillin Acid and Penicillinase Resitant
Scientist have also created broad spectrum penicillin that is effect against Gram + and Gram - bacteria. What is the following broad spectrum penicillin?
Ampicillin (broadened spectrum, acid resistant)
Scientist have also created broad spectrum penicillin that is effect against Gram + and Gram - bacteria. What is the following broad spectrum penicillin?
Amoxicilllin, like ampicillan but more active and requiring less frequent doses
how does the beta-lactum in Penicillins and Cephalosporins precent the binding of NAG and NAM in the Peptidoglycan wall?
The beta-lactum ring chemically resembles the D-Ala-D-Ala piece of peptidoglycan allowing the drug to mimic the sugar binding to the penicillin-binding proteins. Thus, halting their activities and Synthesis of the chain.
How are Semisynthetic drugs formed in Penicillin and Cephalosporins?
By modifying the R group neat the ß-Lactam ring.
What is the first step of peptidoglycan synthesis?
Precursors are made in the cytoplasm (UDP-NAG adn UDP-NAM peptide)
What is the Second step of peptidoglycan synthesis?
The precursors are polymerized to the existing cell wall structure by transglycosylases.
What is the Third step of peptidoglycan synthesis?
The peptide side chains are cross-linked by transpeptidases
True or False
When looking at a Kirby-Bauer Disk Susceptibility test we just find the biggest zone of inhibition to determine the best antibiotic.
False; there is a proportionality to the antibiotics where zones are unique to each antibiotic meaning that a table must be consulted.
What Antibiotic is OX the abreviation of?
Oxacillin
What Antibiotic is P the abreviation of?
Penicillin
What Antibiotic is TE the abreviation of?
Tetracyclin
What Antibiotic is C the abreviation of?
Chloramphenicol
What Antibiotic is E the abreviation of?
Erythromycin
What Antibiotic is VA the abbreviation of?
Vancomycin
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does A denote?
Amino acids add sequentially to n-acetylmuramic acid (NAM)
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does b denote?
D-Alanine peptide attaches
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does C denote?
NAM pentapeptide transfers to bactroprenol
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does H denote?
One phosphate on liberated bactoprenol is removed and lipid moves back to cytoplasmic side of membrane.
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does D denote?
N-acetylglucosamine (NAG) Links to NAM
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does E denote?
Bactroprenol “flips”, moving NAM-NAG to outer side of cytoplasmic membrane
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does F denote?
Transglycosylase attaches new disaccharide unit to existing chain
The following is a Diagram of Peptidoglycan synthesis in a Gram Positive Bacterium. What does G denote?
A penta glycine connets L-Lys on one side chain and the penultimate D-Ala on the other
What does transglycoslase do?
Moves and binds sugars (NAM and NAG)
What does Transpeptidase Do?
Moves and Binds Proteins
What are some Examples of Cell Wall inhibitors?
Penicillins
Cephalosporins
Vancomycin
Bactitracin
Monobactams
Some antibiotics are cell membrane inhibitors and are also toxic to humans. What are some examples?
Polymyxins
Daptomycin
Gramicidin
What are some examples of some NAtibiotic Metabolic Inhibitors?
Sulfonamides
Trimethoprim
Metronidazole
What is an example of DNA Replication Inhinitors?
Quinolones
What is an example of RNA Replication Inhinitors?
Rifampin
Pyronins
What are some examples of Antibiotics that are protein Synthesis Inhibitors that effect the 50S ribosome subunit?
Chloramphenicol
Macrolides (Erythromycin)
Clindamycin
Oxazolidinones (Linezolid)
Streptogramins (Synercid)
What are some examples of Antibiotics that are protein Synthesis Inhibitors that effect the 30S ribosome subunit?
Aminoglycosides (gentamicin)
Tetracyclines (doxycycline)
The figure below represents bacterial cell wall, which of the following antibiotics will bind to the region marked by the arrows?
Vancomycin
Sulfonamides are selectively only toxic to bacterial cells. Why?
Because folic acid is not synthesized by humans.
Penicillin is less effective when used in combination with
bacteriostatic antibiotics such as tetracycline.
According recent study walking pneumonia, caused by mycoplasma pneumonia, is surging in many states including Alabama. Based on the nature of the bacteria responsible for the disease, which of the following antibiotics will be the best for treating the disease.
Clindamycin
Some individuals treated with tetracycline experience cellular damage that is similar to mitochondrial disease because
mitochondrial ribosomes are susceptible to inhibition by tetracycline.
True or False:
Cell wall Antibiotics only work when the bacterial Cell is Growing.
True
Do drugs that affect eth cell Membrane like Gramicidin and Polymyxin ojnly affect bacteria or can they affect humans/
They can Affect Humans
Gramicindin can kill both Bram Pos and Gram Neg Bacteria, and is not used a lot because of the potential harm to humans. What produces this antibiotic and how does it affect the membrane?
It is a cyclic peptide produced by bacillys brevis that forms a cation channel through which ions leak.
Polymyxin (Colistin) only affects gram Negative bacteria, how is it produced and how does it work?
It is produced by Bacillus Polymyxa. and Destroys cell membranes like detergent, specifically the outer membrane by targeting LPS.
What are two types of drugs tat affect DNA Synthesis?
Quinolones
Sulfa Drugs
What are some examples of Quinolones?
Nalidixic acid
Ciprofloxacin
What are the most common class of Quinolones?
Flouroquinoles
What do Quinolones Affect?
Blocks bacterial DNA Gyrase and prevents DNA Replication, this antibiotic is bactericidal.
The first commercially available antimicrobial was Sulfa Drugs what is another name?
Sulfonamide
What is the Mode of Action for Sulfa Drugs?
Analogs of PABA, a precursor of folic acid that is needed for DNA Synthesis. Sulfa drugs mimic PABA prevent the formation of Folic Acid
What is the Purpose of RifamycinB and Actinomycin D?
They are antibiotics that inhibit RNA Synthesis (Transcription) and are bactericidal. (Most active to growing bacteria)
What bacteria has developed a resistant strain against Rifamycin B?
Mycobacterium tuberculosis
What is the mode of Action of Rifamycin B?
Bind to the beta subunit of RNA polymerase and prevent the elongation step of transcription.
True or False
Actinomycin D is bad for humans?
True
What is the mode of action of Actinomycin D?
Prevents the intiation step of transcription by binding to DNA from any source
the antibiotic with its correct mechanisms of action (or cell target)
Rifamycin B
These are some of the antimicrobial agents used to treat human infections. Answer the following question based on the information listed below.
Aminoglycosides
Cephalosporins
Penicillin G
Gramicidin
Which of the above numbered antimicrobials can also destroy human cells
Gramicidin
A newly identified antibiotic was found in soil bacteria. Chemical analysis showed the structure of the antibiotic to be similar to a Para-aminobenzoic acid (PABA) molecule. This newly identified antibiotic would most like be ____.
Sulfanilamide
Zone of inhibition (mm) | |||
Antibiotic | Resistant | Intermediate | Susceptible |
Amoxicillin | < 12 | 12 - 13 | > 13 |
Oxacillin | < 13 | 13 - 17 | > 17 |
Vancomycin | < 14 | 14 - 18 | > 18 |
Ampicillin | < 18 | 18 - 22 | > 22 |
Antibiotic | Zone of inhibition |
Amoxicillin | 14 mm |
Oxacillin | 16 mm |
Vancomycin | 18 mm |
Ampicillin | 22 mm |
The following results were obtained from a disk-diffusion test for microbial susceptibility to 4 antibiotics. MRSA was the test organism.
Based on the results above, which of the tested antibiotics should be used to kill the organism.
Amoxicillin
Natural penicillin and semisynthetic penicillin differ in which of the following
in their R-side chain
What two kinds of drugs affect 30S subunit of ribosome?
Aminoglycosides
Tetracyclines
Aminoglycosides cause the translional misreading of mRNA. What are two examples?
Streptomycin and Gentamicin
Note 
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