antimicrobial chemotherapy Flashcards
what is MBC
mininimal bactericidal concentration
what is MIC
minimal inhibitory concentration
what are the 3 broad ways a bacteria can be killed
inhibition of
cell wall synthesis
nucleic acid synthesis
protein synthesis
what cause inhibition of cell wall synthesis
b lactamases disturpt the binding of peptidoglycans by penicillin binding proteins
what two types of antibiotic do this by beta- lactam
how are they countered
penicillin’s
cephalosporins
beta lactamase
what is the other method of cell wall synthesis
what is the class where do they work
inhibiting assembly of a peptidoglycan precursor
glycopeptides
only on gram positive
what are the 6 examples of protein synthesis inhibition classes
aminoglycosides
serious gram negative infections (coliform)
macrolides
stop A.A binding
alternative to penicillin - GRAM POSITIVE
tetracyclines - sterph resistant
oxazolidinones - stops start codon reorganisation
linezolid- treatment of serious infections
cyclic lipopeptide
daptomycin uses against GRAM POSITIVE
What is parental administering
administering of drug via IV or IM (intra muscular methods)
penicillin G
used in gram positive (gram negative resistant)
inhibition of cell wall synthesis
vancomycin
glycopeptide
before beta lactam stage
only given parentally
only GRAM POSITIVE (aerobic and anaerobic)
gram negative is resistant
toxicity is a common problem
teicoplanin
glycopeptide
before beta lactam
only given parentally
only GRAM POSITIVE
linezolid
''new'' class only one of the oxazolidinones orally - serious infections MRSA (metacycline resistant)
inhibiton of protein synthesis
daptomycin
cyclical lipopeptide
works against GRAM POSITIVE (MRSA) only on specialist advice
imnhibiton of protein synthesis
gentamicin
used in serious gram negatives (coliform)
and staphylococci is also affected
toxicity to renal function is common
inhibiton of protein of synthesis
cheapest to use
what’s important about aminoglycosides
resistance in GRAM NEGATIVES IS V.UNCOMMON
protein synthesis
erythromycin
macrolides alternative to penicillin GRAM POSITVE some staph and streph resistant protein synthesis
clarithromycin
macrolides
alternative to penicillin
GRAM POSITVE
protein synthesis
doxycyclines tetracyclines
are used as a alternative to penicillin and work against gram positive bacteria
protein synthesis
co-trimoxazole
Trimethoprim and sulphamethoxazole
used in the treatment of chest infection instead of cephalosporins
and UTIs
reduce c.diff
inhibition of nucleic acid synthesis
ciprofloxacin
nalidixic acid
Fluoroquinolones
nucleic acid inhibition
particularly effective against NEARLY ALL gram negative bacteria
QUINOLONES
DO NOT USE IN CHILDREN – floating children
taken orally
pseudomonas
levofloxacin
Fluoroquinolones
nucleic acid synthesis
work well against gram negative
but also increased gram POSITVE sensitivity
what are the 2 types of antibiotic resistance
inherent/intrinsic resistance
acquired resistance
what is inherent resistance
resistance that is related more often than not to the cell wall and the lack of penetrating
what is acquired resistance
resistance that varies between strain of bacteria
- either a spontaneous mutation (during bacteria replication)
- resistance genes passed from bacteria to bacteria Plasmids or transposons
what are the two forms of beta- lactam resistance
beta lactamase - common in GRAM NEGATIVE BACTERIA
activity against penicillin and cephalosporins
mutation of penicillin binding proteins
what are the two ways to over come beta- lactamase production
introduce a beta-lactamase inhibitor that protrcts the antibiotic drom degredation enzymes
the other is to modify the penicillin side chain (make it bigger to protect the beta lactam ring)
what is an example of a beta-lactamase inhibitor
co-amoxiclav
amoxicillin plus the b-lactamase inhibitor clavulanic acid
FLUCLOXACILLIN IS ANOTHER EXAMPLE
what is an example of a penicillin modify antibiotic
the antistaphylococcal drug FLUCLOXACILLIN
what are ESBLs
extended spectrum beta lactamases
GRAM NEAGITVIVE
organisms with this resistance are resistant to all beta lactam antibiotics
what are CPEs
Carbapenemase Producing Enterobacteriaceae
Gram negative organisms, resistant to the carbapenems
sometimes leaving NO antimicrobial options
what is the best known bacteria that has altered PBPs
penicillin binding proteins
MRSA
what is the resistance to vancomycin in
vancomycin resistant enterococci (VRE)
GRAM POSITIVES
glycopeptide resistance
staph.aureus
Benzyl penicilli
was the original naturally occurring substance discovered by Fleming and largely acts against gram positive organism
Amoxicillin
better oral absorption than penicillin G
was good for some gram negative but now 30% resistance
Piperacillin
good coverage
gram positive and gram negative - (mainly anti-anaerobic)
Imipenem, meropene
carbapenems - have the widest spectrum of all - active against most bacteria including aerobes
ceftriaxone
cephalosporins
aren’t really used as often culture c.diff
Azithromycin
a macrolide that is useful for single dose chlamydia (miscellaneous bacteria)
what are allergic reactions related to antibiotics
immediate hypersensitivity
- anaphylactic shock
- IgE mediated (within mins)
delayed hypersensitivity
- most common is a rash
- but fevere, sickness can occur
Gastrointestinal side effects
- commonly encountered with antibiotic use
what are the outcomes from Gastrointestinal
common diohrea caused by c.dif (side effect)
c.dif over grows normal bacteria in the prescence of antibiotics
what are the 4 Cs
why is their use being reduced
cephalosporins, ciprofloxacin, clindamycin, co-amoxiclav
reduced use to minimise the killing of all commensal GI flora in
how is clostridium difficicile fought
oral vancomycin
what else can broad spectrum antibiotics cause
thrush
candida albicans
what are the toxicity’s caused by antibiotics
liver (hepatotoxicity) - flucloxacillin, tetracycline
renal - gentamicin (aminoglycoside)
neurological
optic nerve - anti TB drugs
convulsions - high penicillin and cephalosporin
haematology - anti MRSA agent linezolid - bone marrow suppression
plantlets lowered
what is the problem with anti-TB drugs
very toxic especially to the neurological system
how are adverse reactions minimised
use the minimum dose to get the highest efficacy
what are the 3 possible outcomes of microbial combinations
additive/agonist - increase clinical effect
antagonistic- combined effect is less
synergistic - team work (penicillin and gentamicin)
penicillin breaks the cell wall for Gentamicin
when are drugs additive/synergistic
when both are either cidal or static
what are the 4 types of anti-fungal drugs
Allylamines
Echinocandins
Azoles
Polyenes
what do polyene drugs do
examples
bind to ergosterol the fungal cell wall however also cholesTEROL
Amphotericin B - only anti fungal for IV use - extremely toxic to everything but for really serious yeast and fungal infections
Nystatin - topical or oral use for serious fungal infections
what are Azoles
examples what do they do
Inhibit ergosterol synthesis
Fluconazole - non toxic but has some Candida resistance
not all yeast sensitive to fluconazole
Voriconazole and itraconazole are used to treat aspergillosis
what are Echinocandins
examples and what are they used on
inhibit the synthesis of glucan polysaccharide
Caspofungin, Mycafungin and Anidulafungin
used for treatment of serious Candida and Aspergillus infections
what do Allylamines do
example
what is it used on
suppress ergosterol synthesis
terbinafine
fungal infection of skin and nails (athletes foot)
how are anti-virals resistance tested
Genotypic analysis
what is the ONLY type of anti-virals
virustatic
NO VIRUCIDAL
Aciclovir
nucleoside analogue
specific for virus-infected as needs to be coded by virus enzymes
low toxicity
Aciclovir is active against Herpes Simplex virus (cold sores - orally treated) and Varicella zoster virus (IV)
what is the ciclovir for
Anti-Herpes Virus Drugs
why is Foscarnet different
different type of drug which can be used for some HSV, VZV and CMV infections resistant to the nucleoside analogue
highly nephrotoxic
only given IV
what is special about anti HIV treatment
main drug example
Combination therapy- least three drugs
zidovudine
nucleoside analogue - interferes with reverse transcriptase
what are two examples of Drugs for Chronic Hepatitis B and C
Interferon- alpha
produced by genetic engineering - chronic hep B and C
serious side effects, costly
cant be given orally (subcutaneous injection )
Lamivudine - selected patients - hepatitis B.
given orally.
drugs used for viral respiratory infections
Zanamavir and Oseltamivir influenza A or B within 48 hours
Ribavarin
nucleoside analogue
inhaled as a fine spray
treats Respiratory Syncytial Virus (RSV)
What other drugs are used in anti HIV treatment
Squinavir
Drunavir
