Antimicrobials: Background Flashcards
empiric antibiotics (meaning)
based on body part/suspected infection
definitive antibiotics (meaning)
antibiotics based on culture/sensitivity results, which take about 2-3 days.
deescalation of abx
as cultures start to come back, you can eliminate the empiric abx that are not applicable.
penetration of antibiotics is hard in what 3 areas?
bone
lung
CNS
minimum inhibitory concentration (MIC)
Lowest concentration of an antimicrobial that will inhibit the visible growth of an organism.
the lower the MIC,
the more sensitive the drug is.
post-antibiotic effect
after discontinuation, the abx continues to work.
patient specific factors for abx
renal function
hepatic function
age
drug specific factors of antibiotics include what 3 considerations?
IV vs PO
bacteriostatic vs bacteriocidal
cost per day
bacteriostatic
growth inhibiting
bacteriocidal
kills the organism
Bacterial resistance mechanisms (4)
- inactivation by various beta-lactamase
- development of new binding proteins which have decreased affinity for the antibiotics
- decreased permeability of the bacterial cell wall
- modification of cell membrane constituents in certain organisms that prevent penetration
cell wall/cell membrane in bacterial resistance (2)
- cell wall will prevent abx from getting into the cell wall b/c of decreased permeability.
- cell membrane is modified in certain organisms to prevent penetration (ie: proteins, efflux pumps).
proteins: bacterial resistance
some binding proteins have decreased affinity for antibiotics, essentially putting a wall between themselves and the abx.
beta lactamases: bacterial resistance
inactivation of the abx by various beta lactamase enzymes, mainly caused by indiscriminate use of abx.
3 major gram positive organisms
2 minor
streptococcus
staphylococcal
enterococcal
corynebacterium
listeria
gram negative organism examples (7)
escherichia (e coli) klebsiella proteus influenza psuedomonas legionella M cat
“easier” to treat
gram positive aerobes
“harder” to treat
gram negative anarobes
aerobic vs anaerobic in terms of treatment
aerobic is easier to treat than anarobic
example of a spirochete
Lyme disease
organism associated with tuberculosis
mycobacteria
MAC
mycobacteria avium complex
seen in the immunosuppressed.
cell wall active, beta lactam drug groups (4)
- penicillins
- cephalosporins
- thienamycins (“penems”)
- monobactams
cell wall active, non beta lactam drug
vancomycin
cell wall active vs protein synthesis active
cell wall active drugs destroy the cell wall while protein synthesis drugs starve the organism of nutrients.
protein synthesis active drug groups (4)
ahminoglycosides
tetracyclines
macrolides
lincosamides
which antimicrobial group works at the level of DNA gyrase?
fluoroquinolones
which antimicrobial group works at the level of purine synthesis inhibition?
TMP-sulfa
Bacteriostatic drugs
“ECSTaTiC” (6)
Erythromycin Clindamycin Sulfonamides Tetracyclines Trimethoprim Chloramphenicol
Bacteriocidal drugs (6) Very Finely Proficient At Cell Murder
Vancomycin Fluoroquinolones PCNs Aminoglycosides Cephalosporins Metronidazole
