Antimicrobials Flashcards
At what 3 points should an antimicrobial agent be administered/evaluated?
- empirical therapy choice based on patient assessment; 2. pathogen-specific therapy once pathogen is identified; 3. adjust for resistance once drug suscepitibilities known
how is empirical therapy selected?
consider probably/possible pathogens associated with type of disease process in your patient, factoring in personal risk factors, and decide on a broad spectrum antimicrobial
what are the 4 major factors that should be considered when choosing an empirical antimicrobial?
disease process, pathogen, host/patient, potential drugs
what sites are difficult to treat?
CNS, eye, infected vegetation on heart, bone
what type of antibiotic is most effective against diseases with toxin involvement?
antibiotics that inhibit protein synthesis (e.g. clindamycin)
what two components of the history are especially important in determining the etiologic agent?
exposure hx (travel, foods, animals, ill contacts) & infectious disease hx (recent infections, colonization with resistant pathogens)
what public health concerns are important to consider?
possible role of therapy to decrease duration of shedding or period of infectivity
aspects of patient demographic that are especially important when selecting empirical therapy
1) AGE, 2) Co-morbidities, 3) drug allergies & interactions
Don’t give _________ to someone with renal or liver dysfunction.
vancomycin, gentamicin
Don’t give _________ to someone with GI disease/abnormalities.
oral medications
Impact of the Antibiotic/Drug: What to Consider
side-effects, cost, administration, spectum of activity
General features of amoxicillin
Beta-lactam penicillin (inhibits wall synthesis); oral only
Amoxicillin is effective against?
many Streptococci, enterococcus, Gram negatives like haemophilus, E coli, Pasteurella
Use amoxicillin for?
minor respiratory infections such as otitis media, sinusitis, mild pneumonia
What are the best IV drugs for MSSA?
oxacillin/nafcillin
General features of augmentin
beta-lactam penicillin (amox) + beta-lactamase inhibitor (clav acid); oral formation
Augmentin is effective against?
same drugs as amoxicillin + anaerobes, MSSA
Use augmentin for?
minor respiratory infections, also dog/cat bites, pathogens resistant to amox due to beta-lactamase production
What is the IV equivalent for augmentin (oral)?
ampicillin/sulbactam (Unasyn)
Piperacillin/tazobactam (Zosyn) should be used against?
more resistant Gram negative bacteria and anaerobes
General features of ceftriaxone (Rocephin)
beta-lactam cephalosporin, 3rd generation; IV (or IM)
Ceftriaxone is effective against?
Gram neg rods, streptococci, some Gram + (but not MRSA, pseudomonas)
Use ceftriaxone for?
severe infections, including CNS infections (can add vanc if need more gram + coverage)
Ceftazidime and cefepime work well against?
pseudomonas
cephalexin (Keflex)
common oral 1st generation cephalosporin
General features of azithromycin
macrolide (protein synthesis inhibitor); oral (also an IV form)
Azithromycin is effective against?
mycoplasma, chlamydia, pertussis, “atypical” bacteria, respiratory bacteria (altho resistance problem)
Use azithromycin for?
penicillin allergy, mycoplasma pneumoniae, chlamydia trachomatis, pertussis, etc.
General features of clindamycin
lincosamide (protein synthesis inhibitor) that is given both orally and IV
Clindamycin is effective against?
Lots of Gram+, many MRSA, anaerobes, NOT enterococcus
Use clindamycin for?
Oral/dental infections, some Staph, toxin-producing bacteria
Which drug is responsible for the majority of C. diff acquisition?
clindamycin!
General features of vancomycin
glycopeptide (inhibits wall synthesis), IV (oral only for C diff)
Vancomycin is effective against?
Most Gram+ bacteria, including MRSA and C. diff (except VRE)
Use vancomycin for?
severe infections due to Gram + bacteria (add a cephalosporin for gram negative coverage)
General features of metronidazole (Flagyl)
produces toxic nitrates in anaerobic bacteria; oral and IV
Metronidazole is effective against?
Anaerobes
Use metronidazole for?
Gut anaerobes, C. diff (if susceptible), combine to cover Gram neg gut
General features of trimethoprim/sulfamethoxazole (Bactrim, Septra)
sulfonamide (inhibits folate synthesis), oral (also IV form)
TMP-SMX is effective against?
variety of gram+ and gram-, some atyptical (pneumocystis-PCP)
Use TMP-SMX for?
ear infections, UTI, staph skin infection, PCP prophylaxis
General features of gentamicin
aminoglycoside (inhibits protein synthesis); IV only
Gentamicin is effective against?
many gram-, some gram+ (synergistic with ampicillin)
Use gentamicin for?
gram negative coverage; synergy against gram positives
General features of levofloxacin
fluoroquinalone (impacts bacterial DNA synthesis), Oral & IV
Levofloxacin is effective against?
Many Gram+ and Gram-
Use levofloxacin (or ciprofloxacin) for?
adults with sinopulmonary infections, UTI, some skin infections
Possible etiologic agents for lobar pneumonia
- Strep pneumoniae, 2. staph aureus; others: strep pyogenes, oral anaerobes, atypical pneumonias
What empirical antibiotic should be used for lobar pneumonia?
Ceftriaxone (penicillin-resistant pneumococcae) + vancomycin (resistant gram+)
Possible etiologic agents post-appendix rupture
- Gram negative enterics (E. Coli), 2. Anaerobes, 3. Enterococci
What empirical therapy should be used for a ruptured appendix?
Amp+Gent+Metro or Zosyn
Probable infectious etiologies for a bite wound
Pasteurella, Staph aureus, GAS, anaerobes
Treat bite wound with?
augmentin unless found to be MRSA
Empirical therapy for bacteremia, possible septic shock
vancomycin (gram +) + cefepime (for gram- rods)
Probable infectious etiologies for pharyngitis
- strep pyogenes, 2. adenovirus, 3. EBV, etc.
Empirical therapy for a patient with pharyngitis
Throat Culture/Rapid Strep Test –> if positive for RST then treat with penecillin, amox, etc.
Treat GC with?
ceftriaxone
Treat chlamydia with?
azithromycin (short course, less likelihood of yeast infection)
Empirical therapy for osteomyelitis
MRSA treatment – vancomycin
Possible etiologic agents in infant meningitis
E. Coli, GBS, listeria, HSV
Empirical Rx for infant meningitis
Ampicillin + gentamicin or cefotaxime (ceftriaxone contraindicated in newborns)
