antibiotics Flashcards
what are antibiotics
medicines that either destroy microorganisms or prevent them from reproducing
how do all antimicrobial drugs work
by selective toxicity
selective toxicity
antimicrobial drugs interfere with the metabolism or function of pathogen
first antibiotic
penicillin
why are antibiotics effective
they disrupt biochemistry of the bacterial cells
antimetabolics as antimicrobial action
interrupt metabolic pathways such as blocking nucleic acids synthesis causing death
example of antimetabolites
sulfonamides
protein synthesis inhibitors as antimicrobial action
prevent transcription and translation of microbial genes so protein production effected
examples of protein synthesis inhibitors
tetracyclines
-chloramphenicol
cell wall agents as antimicrobial agents
prevent formation of cross linking in cell walls so bacteria killed by lysis
examples of cell wall agents
beta- lactams eg penicilins
cell membrane agents as antimicrobial damage
damage cell membrane so metabolites leak out or water moves in killing bacteria
examples of cell membrane agents
some penicillins
-cephalosporins
DNA gyrase inhibitors as antimicrobial action
stop bacterial DNA coiling up so doesnt fit within bacterium
examples of DNA gyrase inhibitors
quinolone
examples of bacteriostatics
antimetabolites
-protein synthesis inhibitors
name some bacteriostatic antibiotics
sulfonamides
-tetracyclines
-chloramphenicol
example of bacteriacidals
cell wall agents
-cell membrane agents
-DNA gyrase inhibitors
examples of bacteriostatics
penecilins
-cephalosporins
-quinolone
effects of bacteriostatics
stop metabolic pathways like nucleic acid synthesis
-protein synthesis disruption
effects of bacteriocidal
-prevent cross links
-damage cell membranes
-stop DNA coiling to fit in bacterium
when are bacteriocidals given
when dangerous infection caught
-when patient immune system supressed such as transplant patients
-taking immunosupresent drugs
broad spectrum antibiotic
destroys wide range of harmful bacteria pathogens and good bacteria
narrow spectrum antibiotics
targets one of 2 specific pathogens
factors for effectiveness of antimicrobials
concentration of drug in area of body infected
-affected by how easily drug can reach tissue and how quickly its excreted
local pH
whether pathogen or host tissue destroy pathogens
how pathogen reacts to antibiotic used
how can you investigate the effect of different antibiotics on bacteria
-on agar plate inoculated bacterial culture
-filter paper discs with different antibiotics placed on agar covering to ensure oxygen not excluded
-control culture of microorganisms with known sensitivity to antibiotic grown same time under same conditions
-level of inhibition of bacterial growth gives measure of effectiveness of drugs
how is an antibiotic only effective
if microorganism has binding site for drug and metabolic process or pathway antibiotic interferes with
how are bacterias resistant
natural selection
-mutations help bacteria resist antibiotic effects
-mutations become more common and population become resistant to drug
what can mutations also lead to
new biochemical pathways
-switch on or create gene for production of antibiotic destroying enzyme
-become more common
what speeds up mutations of bacteria
wide spread use of antibiotics
how does wide spread use of antibiotics increase resistance
as different antibiotics are used to tackle increasing resistance
-increases selection pressure for evolution of bacteria that are resistant to all of them
MRSA methicillin resistant staphycoccus auerus
resistant to methicillin and cause death
how to reduce antibiotic resistance
reduce selection pressure for resistance by using antibiotics sparingly
-complete course
-use few different ones as possible
-vary them and introduce new ones
problem with new antibiotics use
being developed dropping fast
-bacteria get repeated exposure to same increases likelihood of resistance
superbugs
in hospitals or care homes where people are ill or had surgery
-antibiotic use at its highest
HCAI
healthcare associated infections
examples of HCAI
MRSA and clostridium difficile
effects of catching HCAIs
longer at hospital
-more money spent on patients
-suffering for people infected and family
