Chapter 12 microbial control

What is the goal of antimicrobial therapy?

Administer a drug to an infected person that destroys the infectious agent without harming the person/ host's cells

How are antimicrobial drugs produced?

naturally and synthetically

Does the perfect drug exist?

No, but by balancing drug characteristic's against one another, a satisfactory compromise can be usually achieved

Who was DR Paul Ehrlich

Father of selective toxicity

-Helped with gram staining

-Pharmacology

-Founder of penicillin G

Characteristics of the ideal antimicrobial drug

• Selectively toxic to the microbe but nontoxic to host cells

• Microbicidal rather than microbistatic

• Remains potent long enough to act and is not broken down or excreted prematurely

• Is not subject to the development of antimicrobial resistance

• Complements or assists the activities of the host's defenses

• Remains active even when diluted in body fluids and tissues

• Readily delivered to the site of infection• Reasonably priced

• Does not disrupt the host's health by causing allergies or predisposing the host to other infections

Who discovered penicillin?

Alexander Fleming

Antibiotics

Are common metabolic products of aerobic bacteria and fungi

-Bacteria in genera Streptomyces and Bacillus

-Molds in genera Penicillium and Cephalosporium

What is the Kirby-Bauer test?

Uses antibiotic sensitivity disks to visualize zones of inhibition to see if bacteria are sensitive or resistant to antibiotics.

What drugs does Penicillium form? (is a mold)

Penicillins

Griseofluvin

What drugs does Cephalosporium form? (is a Mold)

Cephalosporin

What is a chemotherapeutic drug?

Any chemical used in the treatment, relief, or prophylaxis of a disease.

What is prophylaxis?

The use of a drug to prevent potential for infection in a person at risk.

What is antimicrobial chemotherapy?

The use of chemotherapeutic drugs to control infection.

What are antimicrobials?

An all-inclusive term for any antimicrobial drug, regardless of its origin.

What are antibiotics?

Substances produced by the natural metabolic processes of some microorganisms that can inhibit or destroy other microorganisms.

What are semisynthetic drugs?

Drugs that are chemically modified in the laboratory after being isolated from natural sources.

What are synthetic drugs?

Antimicrobial compounds synthesized entirely in the laboratory through chemical reactions.

What are narrow spectrum antimicrobials?

Antimicrobials effective against a limited array of microbial types; for example, a drug effective mainly on gram-positive bacteria.

What are broad spectrum antimicrobials?

Antimicrobials effective against a wide variety of microbial types; for example, a drug effective against both gram-positive and gram-negative bacteria.

What should antimicrobial drugs be?

selectively toxic

Selectively toxic

drugs should kill or inhibit microbial cells without simultaneously damaging host tissues

What type of parasite is most similar to humans and tricky to get rid of with drugs due to its severe side effects

Tapeworms/ flukes

Auxotrophy

The inability of an organism to synthesize a nutrient necessary for growth

-Essential!

-Nib

Small molecular/ weight chemical ?

-Mab

monoclonal antibody

-Vir

Antiviral

What are the 5 major components in a cell the drug should target?

1. Inhibition of cell wall synthesis

2. Breakdown of cell membrane structure and or function

3. Interference with functions of DNA and RNA

4. Inhibition of protein synthesis

5. Blockage of key metabolic pathways

What happens if the cell wall is inhibited?

Without a fully formed cell wall, cells are susceptible to lysis due to osmotic pressure

What if the cell membrane is inhibited?

Cell loses its selective permeability

What if DNA and RNA production is inhibited?

Inhibits replication and prevents reproduction

What if protein synthesis is inhibited?

Certain metabolic functions may stop working (IDK NOT SPECIFIED)

What if the metabolic pathways are inhibited?

Enzyme reaction and production will stop (Also not specified lol)

What is the nucleotide backbone made of?

Folic acid

Trimethoprim

Inhibits folic acid metabolism

What drug is best to disinfect a cut in the wound?

Macrolides

What drug fights protozoans best?

Metronidazole

Piperazine

paralyzes worms (but main goal is to paralyze muscular system)

Ivermectin

Inhibits neuromuscular system (ANTI VAXERS use this according to hawkins....LOL?)

What drug is used to combat HIV?

Azidothymidine (Blocks formation of DNA from RNA strand

What is the drug used to fight off MRSA

Vancomycin

What drug is for Candida Albicans

Nyastatin

MDR

multi-drug resistant

Spectrum

range of activity of a drug

Narrow spectrum

Drugs effective on a small range of microbes

-Target a specific cell component found only in certain microbes

Medium or broad spectrum

greatest range of activity; target cell components common to most pathogens

What is the main component of most bacterial cell walls?

Peptidoglycan

How do penicillins and cephalosporins affect the bacterial cell wall?( Know)

They block synthesis of peptidoglycan, causing the cell wall to lyse (Since peptidoglycan is the foundation, without it, it will crumble p much)

Which type of cells are antimicrobial drugs that affect the bacterial cell wall active on?

Young, growing cells

Are penicillins that do not penetrate the outer membrane effective against gram-negative bacteria?

No, they are less effective against gram-negative bacteria

Can broad spectrum penicillins and cephalosporins cross the cell walls of gram-negative bacteria?

Yes, they can cross the cell walls of gram-negative bacteria

What are antimicrobial drugs that disrupt cell membrane?

Polymyxins, Amphotericin B, nystatin

What is the function of these drugs?

To cause disruption in metabolism or lysis of cells with damaged membrane

How do these drugs have specificity for a particular microbial group?

Based on differences in types of lipids in their cell membranes

(Cell membrane destroyer drugs) How do polymyxins, amphotericin B, and nystatin cause leakage in a cell membrane?

Polymyxins interact with phospholipids, amphotericin B and nystatin form complexes with sterols on fungal membranes

(IN A SENSE, THEY MIMIC A CELL MEMBRANE AND DESTABALIZE IT TO CAUSE A LEAKAGE; THINK OF THEM AS LIKE SPIES TRYING TO INFILTRATE SOME SECRET GOVERNMENT AGENCY TO TAKE THEM DOWN)

How do drugs that affect nucleic acid synthesis work?

May block synthesis of nucleotides, inhibit replication, or stop transcription!

What drugs prevent replication?

Antiviral drugs that are analogs of purines and pyrimidines insert in a viral nucleic acid

What does Chloroquine do to affect nucleic acid synthesis?

Binds and cross link the double helix (Inhibits the DNA helicase for replication)

Similarities between cancers and virus

Both grow extremely fast!

How do antimicrobics handle the blockage of protein synthesis?

Antimicrobiotics have selective action against prokaryotes and damage the eukaryotes mitochondria

What does the inhibition of protein synthesis look like?

They inert on sites on the 30S subunit and cause misreading of mRNA (and protein is incorrect)

What does tetracycline do againts protein synthesis?

blocks attachment of tRNA on the A acceptor site and stops further synthesis

How are the ribosomes inhibited?

Because mRNA is misread in protein synthesis due to inhibition, this causes the proteins to be incorrect

-Because protein is incorrect this leads to a blockage of peptide bonds

-Which then prevents the initiation and and block ribosome assembly

-Which ultimately leads tRNA to be blocked, no protein being synthesized and finally ribosome the ribosome is prevented from translocating

How do drugs affect the metabolic pathways?

Via

- competitive inhibition

-Synergistic effect

competitive inhibition

drug competes with normal substrate for enzyme's active site

What are metabolic analog drugs?

Drugs that cannot function as required.

What happens when metabolic analog drugs are used?

Cellular metabolism slows or stops.

Can metabolic analog drugs produce a needed product?

No, they are 'dead-end' and cannot produce the required product.

Name some examples of metabolic analog drugs.

Sulfonamides, trimethoprim, retrovir.

Synergistic effect

The effects of a combination of antibiotics re greater than the sum of the effects of the induvial antibiotics

Example of synergistic effect

Sulfonamides and trimethoprim combined block enzyme required for tetrahydrofolate synthesis needed for DNA and RNA synthesis

How many drug families are there for the 280 different antimicrobial drugs

24

What antibacterial drugs act on the cell wall?

Penicillin and its relatives

• Cephalosporin group of drugs

• Carbapenems and monobactams

• Miscellaneous cell wall inhibitors (non-beta-lactam)

What drugs interfere with protein synthesis?

Aminoglycoside drugs

• Tetracycline antibiotics

• Chloramphenicol

• Macrolides and related antibiotics

A:Aminoglycoside

Tall: Tetracycline

Chimp: Chlroamphenicol

Mews: Macrolides

Beta-lactam

Antimicrobials that contain a highly reactive 3 carbon, 1 nitrogen ring

-MAIN MISSION IS TO INTERFERE WITH CELL WALL SYNTHESIS

What is another name for beta lactamase

penicillinase

What makes beta lactamse

Gram (-) bacteria

Immune to penacillin

What enzyme destroys beta-lactam

beta lactamase

three parts of penicillin

a thiazolidine ring, a beta-lactam ring, and a variable side chain

What are the most important natural forms of penicillins?

Penicillins G and V

What is the drug of choice for gram-positive cocci?

Penicillin

Which bacteria can penicillin be used to treat?

Gram-positive cocci (streptococci) and some gram-negative bacteria (meningococci and syphilis spirochete)

What are some examples of semisynthetic penicillins?

Ampicillin and amoxicillin

What types of infections are semisynthetic penicillins effective against?

Gram-negative infections

Name some penicillinase-resistant penicillins.

Methicillin, nafcillin, cloxacillin

What are the primary problems associated with penicillins?

Allergies and resistant strains of bacteria

What is the significance of cephalosporins in antibiotic administration?

They account for one-third of all antibiotics administered.

How is the beta-lactam structure of cephalosporins altered?

It is synthetically altered.

What is the spectrum of activity for cephalosporins?

They are relatively broad-spectrum and resistant to most penicillinases.

What is the advantage of cephalosporins in terms of allergic reactions?

They cause fewer allergic reactions compared to other antibiotics.

How are cephalosporins administered?

Some are given orally, while many must be administered parenterally.

What are the common root names for generic cephalosporins?

The generic names have root - cef, ceph, or kef.

Drug in the carbapenems category

Imipenem

Imipenem -

broad-spectrum drug for infections with aerobic and anaerobic pathogens; low dose, administered orally with few side effects

Drug in the monobactams category

Aztreonam

Aztreonam

- narrow-spectrum drug for infections by gram-negative aerobic bacilli; may be used by people allergic to penicillin

What is Vancomycin? (Most effective drug for MRSA)

Narrow-spectrum antibiotic effective against Staphylococcal infections.

What are the non-beta lactam cell wall inhibitors?

Bacitracin

Isoniazid

Vancomycin

Brian: Bactitracin

Inhales: Isoniazid

Vape: Vancomycin

When is Vancomycin most effective?

In cases of penicillin and methicillin resistance or if patient is allergic to penicillin.

What are the characteristics of Vancomycin?

Toxic and hard to administer; restricted use.

What is Bacitracin?

Narrow-spectrum antibiotic produced by Bacillus subtilis; used topically in ointment.