Antimicrobial Chemotherapy - Mechanisms of bacterial resistance Flashcards
What is a resistant organism?
an organism which is unlikely to respond to attainable levels of drug in tissue
what is inherent / intrinsic resistance?
all strains of the bacteria are naturally resistant
give an example of inherent resistance.
streptococci is always resistant to ahminoglycosides
what is acquired resistance?
there is resistance in some strains - lab testing required
how many acquired resistance of drug be acquired and how may it spread?
acquired by a spotanaeous mutation.
spread by plasmids or transposons
what are are two ways that bacteria can become resistant to b - lactams?
by producing b - lactamase
by altering the penicillin binding sight
How does b - lactamase work?
its cleaves the b - lactam ring to make it inactive
is b - lactamase common in gram positive or gram negative organisms?
gram negative
what bacteria tends to produce b- lactamase?
staph. aureas
how can bacteria get around being faced with a b - lactamase?
- add b - lactamase inhibitor
- modify antibiotic side chain to get resistant to b- lactamase
give an example of a drug that has an added b - lactamase inhibitor, and name the original drug?
co - amoxiclav
antibiotic - amoxicillin
inhibitor - clavulanic acid
give an example of a drug that is modified to be resistant to b - lactamase
flucoxacillin
what is an ESBL?
extended spectrum b- lactamases
what type of bacteria may produce ESBL?
negative
what generation of cephalosporin can ESBL break down?
third
are ESBLS resistant to all B - lactams?
Yes
What are CPE and CRE?
carbapenemase producing enterobacteriacaea
carbapenem resistant enterobacteriacaea
what are CPE and CRE extremely resistant too?
Gram negative bacteria.
No antimicrobial options
what are carbopenams.
antibiotics that cover a broad range of illnesses that CPE and CRES are resistant too.
How do bacteria develop a resistance to glycoproteins?
by altering their peptidoglycan precursor target site
name two vancomycin resistant bacteria.
enterococcus faecium
enterococcus faecalis
what are some other methods of antibiotic resistance?
blocking transport of drug into cell
stimulating active transport of drug out of cell
