Ch. 20 Flashcards
Selective toxicity
Antimicrobial drugs are chemicals that kill microbial cells but not host cells
Narrow spectrum
Ex:
Treats a smaller range of different microbial types.
Ex.: penicillin G affects gram-positive but very few gram-negative bacteria
Broad-spectrum
Antibiotics treat a broad range of gram-positive and gram-negative bacteria
Bactericidal
Kill microbes directly
Bacteriostatic
Prevent microbes from growing (host uses phagocytosis and anti-bodies to destroy microbe)
What is a superinfection?
And overgrowth of a pathogen that has developed a resistance to an antibiotic.
An antibiotic resistant strain replaces the original sensitive strain, and the infection continues.
What are the five major anabiotic mode of action?
- Inhibitors of cell wall synthesis
- Inhibitors of protein synthesis
- Injury to the plasma membrane
- Inhibitors of nucleic acid replication and transcription
- Inhibition of essential metabolite synthesis.
Chemotherapy
The treatment of disease by the use of chemical substances. Paul Ehrlich from Germany coined the term chemotherapy where he was looking for a magic bullet to destroy pathogens without harming their host.
1909
How does selective toxicity work?
Antimicrobial drugs must often act within the host without damaging the host. Antimicrobial drugs act by killing or by interfering with the growth of microorganisms.
What causes a super infection?
A broad-spectrum antibiotic that does not destroy certain organisms in the normal microbiota but does destroy their competitors, the survivors may flourish and become opportunistic pathogen’s that sometimes occurs in overgrowth by the east like fungus Candida albicans
In order for antibiotics to be effective it must be able to demonstrate?
Selective toxicity
Antibiotic therapy is a form of?
Chemotherapy
Where do most antibiotics come from?
Bacteria (most from the filamentous soiled bacteria)
In Table 20.2, what is the spectrum of activity of antibiotics and other antimicrobial drugs showing?
The bacterial (prokaryotes) antibiotics have a broader spectrum then the fungal (eukaryote) ones.
Which is better a broader or narrow spectrum anabiotic and why?
Narrow because the broad-spectrum wipes out everything including the normal microbiota and contributes to anabiotic resistance.
What are some acceptable uses of broad-spectrum antibiotics?
- When there’s question about what the patient may be infected with
- Prophylaxes for most surgical procedures
What are the different groupings of penicillin?
Natural
Semisynthetic
What does natural penicillin work mainly on?
- Gram-positive bacteria and spirochetes
* Penicillin G & Penicillin V
Penicillinase is also known as?
B-lactamases
What is penicillinase?
Enzymes that break down the B-lactam ring
In order for antibiotics to be effective it must be able to demonstrate?
Selective toxicity
Antibiotic therapy is a form of?
Chemotherapy
In Table 20.2, what is the spectrum of activity of antibiotics and other antimicrobial drugs showing?
The bacterial (prokaryotes) antibiotics have a broader spectrum then the fungal (eukaryote) ones.
Which is better a broader or narrow spectrum anabiotic and why?
Narrow because the broad-spectrum wipes out everything including the normal microbiota and contributes to anabiotic resistance.
What are some acceptable uses of broad-spectrum antibiotics?
- When there’s question about what the patient may be infected with
- Prophylaxes for most surgical procedures (Abdominal or G.I. tract in particular, if there’s any bacteria that leak out of the organ system and into the abdominal cavity, which is a life-threatening infection)
Three groups of beta-lactam antibiotics (Inhibitors of cell wall synthesis). In the order of development:
1) Penicillin
2) Cephalosporins
- On the fifth generation
3) Carbapenems
What are the different groupings of penicillin?
Natural
Semisynthetic
What does natural penicillin work mainly on?
- Gram-positive bacteria and spirochetes
* Penicillin G (Injection) and Penicillin V (Orally)
Penicillinase is also known as?
B-lactamases
What are the advantages of a semisynthetic penicillin?
- Broad-spectrum
* Resistant to penicillinase
What are some examples for semisynthetic?
- Ampicillin
Is still susceptible to some penicillinase but has ^ the spectrum of activity. Gram-negative. - Amoxicillin
- Oxacillin
Narrow Spectrum. Doesn’t give an increase spectrum but it’s more resistant to penicillinase and for gram-positive only.
Carbapenems
- Primaxin
- Doripenem
Useful against a host of bacterial infections including pseudomonas
What’s the most common penicillin that can block B-lactamases?
Augmentin (Amoxicillin + Clavulanic Acid)
This blocks B-lactamase non-competitively. It’s a non-competitive inhibitor. It binds to a site other than the active site, but still disabled the enzyme.
What do penicillinase/B-lactam love to attack?
B-lactam ring
What bacteria have become resistant to carbapenem?
KPC (Klebsilla Pneumonaie)
Why was Cephalosporins developed?
Because the bacteria began making penicillinase and became antibiotic resistant to penicillin
What antibiotics inhibit protein synthesis?
1) Tetracyclines
2) Macrolides
Tetracycline
- Trade name is Doxycyline
- Don’t use if pregnant
- Used to treat STI’s (particularly chlamydia), a variety of gram positive and gram negative bacteria, respiratory infections, and Rickettsias
Macrolides
- Erythromycin
- Azithromycin
- Used to treat: Sinus and Ear infection
Why do they call them Macrolides?
Because of the big complex ring, macrocyclic lactone ring
Why do they call these chemical group tetracycline?
Because it has four cyclic ring structures
What are The different drugs that belong to the antifungal group?
- Polyenes
* Azoles
The common standby antifungal drugs belongs to a group called the Polyenes, what’s it called?
Amphotericin B
Most antifungal’s interfere with the incorporation of ______ into the cell membrane.
Ergosterol
What type of sterol do mammals like us have in our cell membrane, but you don’t find them in plants?
Cholesterol
Competitive enzyme inhibition includes what?
Sulfonamides
Sulfa Drugs
What’s the third and last line of defence and the most potent that inhibit cell wall synthesis of the B-lactam drugs?
Carbapenems
Are broad-spectrum is resistant to penicillinase?
Yes, A noncompetitive inhibitor. It binds to a site other than the active site, but still disabled the invite
What group/genus of bacteria often make penicillinase?
Staphylococcus (Beginning to get VERSA )
How does Amoxicillin and Clavulanic Acid work together?
- Amoxicillin is semi synthetic penicillin
* Clavulanic Acid is the compound that in activates penicillinase.
How do natural and semisynthetic penicillin structurally differ and what to do they have in common?
- Common: Nucleus and B-lactam ring
* Differ: R groups (The side group that’s attached to the common nucleus)
What does semisynthetic mean?
You originally get it from a natural source and then begin tweaking it.
Why do the cephalosporins keep growing and generations?
Because of resistance
What are the antibiotics that don’t require a prescription for?
- Bacitracin
- Neomycin (Broad-spectrum aminoglycoside)
- Polymyxin B
- Topical ointment
Why isn’t a prescription needed for those three antibiotics?
Because they’re available in small dilute quantities but work just as well
Antimycobacterial Antibiotics:
Name antimycobacterial antibiotic:
Isoniazid
Antimycobacterial antibiotic:
Isoniazid is taken in combination with?
They treat?
- Rifampin
- Ethampin
- Used to treat TB
What does antimycobacterial antibiotics inhibit?
- Inhibit the synthesis of mycolic acid, which is the waxy stuff, so the cell wall is denied mycolic acid so it falls apart.
- So they either inhibit the synthesis of mycolic acid or allow it but blocks it’s intersection into the cell wall
Antimycobacterial Antibiotic:
Name some facts about Teixobactin?
- Known as the next big break through anabiotic
- Interfere with cell wall synthesis
- Been demonstrated in all non-human trials to knock out all gram-positive bacteria including MRSA
- Disrupts the synthesis of teichoic acid, which is an integral part of the cell wall it will fall apart without these acids
Nucleic acid synthesis inhibitors include what?
Fluroquinoines
Name some of the well known Fluroquinoines and what are they commonly used for:
- Ciprofloxacin
- Originally for anthrax
- Levoquin
- Norfloxacin
- Use for UTIs and pneumonia
Competitive and Enzyme inhibition:
Was probably the most famous sulfonamide drug, what’s the combination of this drug and what’s it used to treat?
- Bacterium
- Combination: Sulfamethoxazole-Trimethoprim)
- Treats: MRSA and UTI
Azoles
- Ex: Miconazole (Vaginal yeast infection) and Clotrimazole (Athletes foot)
- Both topical application
Name some anti-protozoan drugs:
- Flagyl
* Artemisinin
Anti-protozoan drug:
What is Flagyl used to treat?
Treats vaginitis caused by Trichomonas vaginitis (Works because it’s a protozoan)
Anti-protozoan drug:
Artemisinin
- It’s a plant extract used to prevent and treat malaria
- Consider the last line of defense against malaria, the last chemotherapeutic agent of defense and treatment.
- Roughly 3 years ago artemisinin resistant malaria came out
- They’re trying something called ACT (Artemisinin Combinatorial Therapy) where they’ll combine artemisinin with quinin based drugs in an attempt to prevent it as well as knock it out
Name an anthelminthic drug and what’s used to treat?
- Niclosamide
* Treats Tapeworm Infections
Why did scientist start getting into the semisynthetic penicillins?
Because of the resistance and you can broaden its spectrum
What does penicillin do?
It blocks the enzyme that assembles the rods of the carbohydrate backbones.
What’s inside the common nucleus that’s attacked at penicillinase?
B-lactam ring
What’s the most commonly prescribed B-lactam antibiotics?
Cephalosporins
What are some examples of cephalosporins?
- Cephalothin
* Cefixime
Why were the carbapenes developed?
To increase the spectrum of activity and because of their resistance to penicillinase
What group does vancomycin belong to?
Polypeptide antibiotic, also inhibits cell wall synthesis but not a B-lactam drug
R Factor
A plasmid that allows bacteria to become resistant to one or more antibiotics
HAART
- Highly active antiretrovirals therapy
* Cocktail therapy for HIV
What are some common ways bacteria can defeat antibiotics?
1) Block the entry
2) Efflux pumps
3) Inactivates enzymes
4) Alter the target molecule
The most famous Fluroquinoines ?
Ciprofloxacin
Vancomycin treats ?
C. difficile and MRSA
