antimicrobial drugs and resistance

what are antimicrobial drugs

compounds that inhibit or kill the growth of microorganisms

What is selective toxicity

Damage to pathogen without harming the host

What are the two types of antimicrobial drug effects

-cidal and -static

What does the spectrum of activity refer to in antimicrobial drugs

Rang of microbes affected by the drug

What is a narrow spec. antiobiotic

Affects only microbes within a limited group

What is an example of a narrow spec. antibiotic

Penicillin G - works against Gram positive bacteria

What is a very narrow spec antibiotic

Affects only a very specific group

What is an example of a very narrow spec. antibiotic

Isonazid - works against mycobacteria

What is a broad spec. antibiotic

works against a wide range of microbes

What is an example of a brad spec. antibiotic

Tetracycline - works against both gram negative and gram positive

What does an antibiotic that inhibits synthesis of LPS affect

It affects Gram negative bacteria

What does an antibiotic that inhibits endosposre formation affect?

It affects Gram positive bacteria

What are growth factor analogues

Structurally similar to growth factors, interfere with metabolism

how do sulfa drugs inhibit bacterial growth

They interfere with folic acid synthesis

structurally similar to PABA

What is a characteristic of quinalones

They interfere with DNA replication in bacteria

what enzyme do quinalones target

DNA gyrase

what is an example of a quinalone

ciproflaxcin

how does resistance to ciproflaxcin occur

Mutation of DNA gyrase binding site

what is an antibiotic

antimicrobial agent produced by other microorganisms

why are most antibiotics semi-synthetic

natural antibiotics are modified to change properties

What is the active structural component of β-lactam antibiotics?

β-lactam ring

How do β-lactam antibiotics work?

They inhibit bacterial cell wall synthesis

bind to penicillin binding proteins

what enzyme do some bacteria produce to resist β-lactam antibiotics

β-lactamase

what do semi - synthetic penicilins’s do?

alter the activity through changes to side chains

What is methicillin designed to do?

fight multiple antibiotic resistant S.aureus

What is MRSA

methicillin resistant S. aurues

cephalosporins

structurally different from penicillins, but include β-lactam ring

Broad spec

more resistant to β-lactamase

treat infections by penicillin resistant Gram negative bacteria

what is ceftriaxone

A third generation cephalosporin antibiotic

How does ceftriaxone differ from penicillins?

It has a broader spectrum and more resistance

what is vancomycin used for

first line treatment against MRSA

Very narrow spec.

what is the modes of action of vancomycin

Blocks cross-linking of peptidoglycan

what are aminoglycosides

Protein synthesis inhibitors targeting the ribosome

what do aminoglycosides target

target 30S subunit

what is an example of aminoglycosides

streptomycin

macrolides

structure based on lactone rings

what is an example of macrolides

erythromycin

What do macrolides target

50S subunit

narrow spec.

what produces tetracycline

Streptomyces aureofaciens

what does tetracycline inhibit

30S subunit

what is the spectrum of tetracycline

Broad spec, heavily used antibiotics

what is daptomycin

a cyclic lipopeptide antibiotic

how does daptomycin work

forms pores in the cell membrane

Narrow spec.

last resort AB against MRSA

what is platensimycin

A novel antibiotic inhibiting fatty acid biosynthesis

what is platensimycin not clinically useful

Humans clear the drug too fast

what microorganism produces paltensimycin

streptomyces platensis

what is intrinsic resistance

Natural resistance to one or more antibiotics

What is acquired resistance

ability to resist effects of normally sensitive agents

how can resistance genes be transferred

Through horizontal genes transfer

what is one mechanism of antibiotic resistance

inactivation of the drug by enzymes

e.g beta lactamases

what is metabolic by pass in antibiotic resistance

acquiring systems that reduce dependence on antibiotics

how do some bacteria decrease drug uptake ?

by modifying porin proteins

how do bacteria modify drug targets

by altering ribosomal proteins

what are efflux pumps

transporters that expel antibiotics from the cell

how does antibiotic overuse contribute to resistance?

it selects for antibiotic resistance strains

what is the consequence of antibiotic resistance in pathogens

infections become difficult to treat

what is the role of infection prevention in combating resistance

it reduces the spread of resistant strains

why is rapid diagnosis important in preventing resistance

it ensures appropriate use of antibiotics

What is prudent use of antibiotics

using antibiotics only when necessary

how can transmission of resistant bacteria be prevented

through proper hygiene and sanitation practices