TOPIC 7- Antimicrobial Drugs and Resistance

antimicrobial

compound that inhibits growth (-static) or kills (-cidal) a microorganism in a human or an animal

• selective toxicity- only attacks foreign cells and not the human’s cells

narrow spectrum

affects only microbes within a limited functional group

• penicillin only attacks gram positive bacteria

very narrow spectrum

affects only a very specific group (phyla / species) of bacteria

• isoniazid is only effective against mycobacteria

broad spectrum

works against a wide range of microbes from a singular domain

• tetracycline works on both gram negative and gram positive bacteria

growth factor analogous

type of synthetic antimicrobial drug that:

quinolenes

type of synthetic antimicrobial:

• interferes with DNA replication

• broad spectrum

• Ex: Ciprofloxacin which targets DNA gyrase

DNA gyrase

enzyme involved in the supercoiling of DNA

antibiotic

antimicrobial agent produced by other microorganisms

beta-lactam antibiotic

antibiotic that includes a beta-lactam ring

• the function of the beta-lactam ring is to block crosslinking so the cell walls of the bacteria are weak

• binds to a periplasmic protein called the penicillin binding protein

• only works when the bacteria is actively growing

methicillin

semi-synthetic penicillin

• designed to fight the antibiotic-resistant S. aureus

• resistant to beta-lactam

• resulted in MRSA, methicillin-resistant S. aureus

beta-lactamase

enzyme produced by beta-lactam resistant bacteria which cuts the beta-lactam ring thus rendering the antibiotic ineffective

amipicillin

semi-synthetic penicillin

• broad spectrum and acid stable

cephalosporine

a type of beta-lactam antibiotic:

• more resistant to beta-lactamase

• better against gram negative bacteria bcuz they can penetrate the membrane better

• used to treat infections by penicillin resistant bacteria

vancomycin

cell wall synthesis inhibitor

• blocks the cross-linking of penicillin but don’t include beta-lactam ring

• narrow spectrum; blocks MRSA (only specific gram positive)

• big molecule so it is more likely to cause an allergic reaction

aminoglycosides

disrupts protein synthesis

macrolides

protein synthesis inhibitor

• made by streptomycin

• structure is based on the lactone ring

erythromycin

a type of protein synthesis inhibitor, macrolides

tetracycline

type of protein synthesis inhibitor

daptomycin

made by S. roseosporus

• made by non-ribosomal protein synthase (assembles amino acids into chain, not a ribosome)

• depolarizes the membrane by forming a hole in it

• narrow spectrum against gram positive bacteria

  • last resort against MRSA

platensimycin

mechanisms of antibiotic resistance

• inactivation of the drug

• metabolic bypass

• modification of the drug bypass

• decreased uptake

• efflux pumps

ways to prevent antibiotic resistant

• infection prevention

• rapid and conclusive diagnosis

• appropriate and prudent use of antibiotics

• prevention of transmission of disease