Antimicrobial Drugs and Antibiotic Resistance Exam 4

Antibiotic

any agent that inhibits growth of or destroys BACTERIAL organisms

Drug

any chemical that alters physiology

Synthetic drug

completely created in a lab

semisynthetic drug

naturally occurring antimicrobial altered in a lab

selective toxicity

effective antimicrobial will be more harmful to pathogen than to host

chemotherapy

use of drug to treat disease

chemoprophylaxis

use of drug to prevent disease

bacteria

Which type(s) of Microorganisms do Antibiotics target

bacteria are prokaryotic and therefore very different from eukaryotic host

Why are there more Antibiotic drugs available than Antiviral and Antifungal Drugs

inhibition of enzymes which prevent adding new peptidoglycan, inhibition of tetra peptide bond formation, and prevent NAM and NAG from leaving cell

types of inhibition of cell wall synthesis

Inhibition of enzymes which prevent adding new peptidoglycan

B-lactams prevent linkage of NAM-NAG chains

inhibition of tetra peptide bond formation

only effect bonds w/ particular alanine-alanine bridges

prevent NAM and NAG from leaving cell

NAM and NAG stays in cytoplasm

30s and 50s

types of inhibition of protein synthesis

alters subunit shape and blocks tRNA docking site

types of 30s

inhibit translation by blocking enzymatic site and prevents ribosome from reading codons

types of 50s

alters subunit shape

causes misreading of codons

blocks tRNA docking site

inability to add amino acids

inhibit translation by blocking enzymatic site

prevents translation

prevents ribosome from reading codon

prevents movement from codon to codon

disruption of plasma membrane

binds LPS of gram - cells, disrupts inner and outer membranes and results in cell lysis

PABA analogue and dihydrofolic acid analogue

types of inhibition of nucleotide synthesis

PABA analogue

Complete w/ PABA for binding of active site of enzyme and results in decreased dihydrofolic and decreased nucleotides

dihydrofolic acid analogue

results in decrease of tetrahydrofolic acid and decrease of nucleotides

inhibition of nucleic acid synthesis

very few drugs use this mechanism; inhibits DNA gyrase

spectrum of action, safety and side effects, therapeutic index, and effectiveness

clinical considerations for drugs

broad spectrum

work against many different pathogens

narrow spectrum

works against few pathogens

sensitivity if bacteria to antibiotics

Usage of KB test

agar plates used to show where bacteria grows based on antibiotic effectiveness

how is KB performed

zone of inhibition

areas where bacteria do NOT grow

if every antibiotic diffused from disc evenly

when is largest zone most effective

if antibiotics did not diffuse evenly

when is diameter of zone and standard table used

sensitive, intermediate, resistant

3 possible KB results

minimum inhibitory concentration

smallest amount of antibiotic that inhibits growth of pathogen

broth dilution and Etest

tests used to determine MIC

Etest

Which test can be used to determine both Antibiotic Sensitivity and MIC

Therapeutic index

Ratio b/w dosage that causes a toxic/lethal effect and dosage that causes therapeutic effect

Helps determine dosage of drug that can be safely given to patient

Why is TI used

Toxic dose / effective dose

how is TI calculated

large

When determining the TI of a drug, do we want a large value for TI or a small value

enzymes which neutralize drug, block drug from entering cell, alter shape of receptors so drug cant bind, efflux pumps and biofilm

commons ways bacteria develop antibiotic resistance

Efflux pumps

Which mechanism can create Bacteria with Resistance to Multiple Antibiotics

maintain sufficient levels of antibiotics until immune system can destroy the bacteria, use multi antibiotic therapy, limit use if antibiotics to only whats necessary, and modifying existing drugs

common practices to prevent antibiotic resistance

Fungal

Which infection is Azole; inhibits synthesis of plasma membrane

Protozoal

Which infection is Metronidazole; inhibits DNA synthesis

viral

Which infection is azidothymine; inhibits synthesis of nucleic acids

penicillin

Which drug is Inhibition of Cell Wall Synthesis

Fluoroquinolone

Which drug is Inhibition of Nucleic Acids

Polymixin

which drug is Disruption of Plasma Membrane

Tetracycline

Which drug is Inhibition of Protein Synthesis

Sulfonamide

Which drug is Inhibition of Metabolic Pathway

50s

Which subunit is Chloramphenicol

30s

Which subunit is Aminoglycoside

30s

Which subunit is Tetracycline

50s

Which subunit is Macrolide

PABA

Sulfonamides inhibit the creation of Bacterial Nucleotides because they are Structural Analogues of

KB test and Etest

Tests that can be used to determine whether an Antibiotic is effective against a specific bacteria 

B-Lactamase

Some bacteria produce a(n) enzyme, called