Principles and Mechanisms of Antimicrobial Therapy

Antimicrobial Therapy

Use of drugs to treat infections effectively.

Selective Toxicity

Drug harms infective agent without harming host cells.

Ideal Antimicrobial Drug

Easily administered, effective, and safe for host.

Antibiotic

Microbial substance inhibiting another microbe's growth.

Pathogen Identification

Determining the specific infectious agent present.

Drug Susceptibility

Pathogen's sensitivity to various antimicrobial drugs.

Kirby-Bauer Technique

Method to test antibiotic effectiveness on bacteria.

Zone of Inhibition

Area around antibiotic disc where bacteria cannot grow.

E Test

Determines minimal inhibitory concentration using plastic strip.

Minimum Inhibitory Concentration (MIC)

Smallest drug concentration inhibiting visible microbial growth.

Tube Dilution Test

Serial dilution method to determine MIC in broth.

In Vitro Activity

Drug effectiveness tested outside a living organism.

In Vivo Effect

Drug effectiveness tested within a living organism.

Polymicrobial Infection

Infection caused by multiple pathogens simultaneously.

Therapeutic Index

Ratio of toxic dose to therapeutic dose of drug.

Preexisting Conditions

Patient's health issues affecting drug treatment.

Synergistic Effects

Combined drug effects enhancing therapeutic outcomes.

Cell Wall Synthesis Inhibition

Targeting bacterial cell walls to kill bacteria.

Peptidoglycan

Unique bacterial cell wall component absent in humans.

Antibacterial Drugs

Target differences between prokaryotic and eukaryotic cells.

Broad-Spectrum Antibiotics

Effective against a wide range of bacteria.

Narrow Spectrum Antibiotics

Target a limited range of microbial types.

Superinfection

Overgrowth of resistant pathogens after antibiotic use.

Normal Microbiota

Beneficial microbes normally present in the host.

Antimicrobial Sensitivity Testing

Assessing pathogen response to various antimicrobial agents.

Direct Examination

Rapid detection of pathogens in body fluids.

Incubation

Allowing microbial growth under controlled conditions.

Antimicrobial Chemotherapy

Use of drugs to eliminate infectious agents.

Bactericidal

Kill microbes directly, leading to their death.

Bacteriostatic

Prevent microbial growth; relies on immune system.

Chemotherapy Goals

Disrupt organism's structure or function for survival.

Cell Wall Synthesis Inhibition

Targeting bacterial cell wall construction mechanisms.

Ribosome Inhibition

Interfering with protein synthesis in bacteria.

Nucleic Acid Inhibition

Affecting RNA and DNA structure and function.

Cytoplasmic Membrane Interference

Disrupting membrane structure or function in microbes.

Folic Acid Synthesis Inhibition

Blocking essential metabolic pathways in bacteria.

Selective Toxicity

Targeting bacterial cells without harming host cells.

Penicillins

Group of antibiotics with a β-lactam ring.

β-lactam Ring

Core structure found in penicillins and carbapenems.

Natural Penicillins

Extracted from Penicillium fungi; susceptible to penicillinases.

Semisynthetic Penicillins

Modified penicillins resistant to penicillinases.

Ampicillin

A semisynthetic penicillin with broad-spectrum activity.

Amoxicillin

A semisynthetic penicillin, similar to ampicillin.

Carbapenems

Broad-spectrum antibiotics with β-lactam ring structure.

Cephalosporins

Antibiotics similar to penicillins; widely used.

Polypeptide Antibiotics

Small proteins with antimicrobial properties from bacteria.

Bacitracin

Topical antibiotic effective against gram-positive bacteria.

Vancomycin

Last-resort antibiotic against MRSA, prevents peptidoglycan incorporation.

MRSA

Methicillin-resistant Staphylococcus aureus, antibiotic-resistant bacteria.

Peptidoglycan

Structural component of bacterial cell walls.

Penicillinases

Enzymes that inactivate penicillins and β-lactam antibiotics.

Gram-positive Bacteria

Bacteria with thick peptidoglycan cell walls.

Antimicrobial Spectrum

Range of activity against different microbial types.

Antibacterial Antibiotics

Drugs that inhibit bacterial growth or replication.

Inhibitors of Cell Wall Synthesis

Antibiotics that disrupt bacterial cell wall formation.

Antimycobacterial Antibiotics

Target mycolic acid in mycobacterial cell walls.

Isoniazid

Inhibits mycolic acid synthesis in bacteria.

Selective Toxicity

Targets bacterial structures without harming host cells.

70S Ribosomes

Bacterial ribosomes targeted by certain antibiotics.

Adverse Effects

Unintended consequences of antibiotic treatment.

Aminoglycosides

Antibiotics that alter 30S ribosomal subunit shape.

Streptomycin

An aminoglycoside antibiotic causing mRNA misreading.

Gentamicin

An aminoglycoside antibiotic used against gram-negative bacteria.

Tetracyclines

Broad-spectrum antibiotics interfering with tRNA attachment.

Polymyxin Antibiotics

Effective against gram-negative bacteria by damaging membranes.

Lipopeptides

Lipids linked to peptides with antibacterial properties.

Daptomycin

Targets gram-positive bacteria's cell membranes.

Polymyxin B

A polymyxin antibiotic effective against gram-negative bacteria.

Polyenes

Antifungal agents disrupting fungal membrane sterols.

Nystatin

A polyene antifungal used for skin infections.

Amphotericin B

Broad-spectrum antifungal targeting membrane sterols.

Quinolones

Inhibit bacterial DNA gyrase and topoisomerase.

Rifampin

Inhibits bacterial RNA polymerase and mRNA synthesis.

Sulfonamides

Inhibit folic acid synthesis in bacteria.

Trimethoprim

Combined with sulfamethoxazole for enhanced antibacterial effect.

Antimetabolites

Compete with substrates for microbial enzymes.

Antiviral Drugs

Target various stages of viral replication.

Entry and Fusion Inhibitors

Block virus entry into host cells.

Nucleoside Analogs

Resemble nucleotides, terminating DNA/RNA synthesis.

Persister Cells

Survive antibiotic exposure due to genetic traits.

Superbugs

Bacteria resistant to multiple antibiotics.

B-lactamase

Enzyme that inactivates beta-lactam antibiotics.

Mechanisms of Resistance

Strategies bacteria use to evade antibiotic effects.

Antibiotic Misuse

Improper use leading to antibiotic resistance.