Antimicrobials Flashcards
Antibiotics that are given when there is a strong
possibility of an established infection are termed
presumptive (examples include acute cholecystitis and
acute pancreatitis of less than 24 hour duration).
Intrinsic Patient Risk: The following conditions are known to increase the risk of surgical wound infections;
- Diabetes
- Chronic immunosuppressed states
- Recent corticosteroid use
- Prolonged hospitalization
- Perhaps obesity
- d Preexisting infection
Individual risk for surgical wound infections
- > 3 underlying medical diagnosis
- Abdominal operations > 2 hours
- Contaminated or dirty procedures
- ASA pre-op assessment score >=3
Most neurotoxic ABT
Polymixin (Nephrototic and Neurotoxic)
All enzymes are
Proteins
Five most common organisms found in surgical wounds
include;
Staph Aureus
Enterococcus
Coagulase-Negative Staph (ex. Staph. Epidermidis), E.Coli, and Pseudomonas Aeruginosa
1st generation have
No anaerobes
Biliary tract
Gram negative aerobic (Ecoli, Klebsiella, Enterobacter
Associated with Heart valves
Enterococcus
Gram + Narrow spectrum
Vancomycin
Antibiotics should be delivered to target tissues
prior to initial incision.
It is recommended that antibiotics be given
preoperatively in the OR before induction of anesthesia.
No sooner than 1 hour prior to the procedure.
If the procedure is long (ex. >4 hours)
then subsequent doses may be required, depending on the individual patient and antibiotic used.
Colorectal surgery
Cefoxitin or cefotetan 2g x 1 or cefazolin <120 kg:2g IV≥120 kg: 3g
Plus metronidazole 500mg or ampicillin-sulbactam 3g or
Oral used in conjunction with bowel prep
Neomycin plus erythromycin base or metronidazole
Most surgeries
Cefazolin < 120 kg : 2g Kg; >120kg 3 G IV
Cardiac surgery dose
Cafazolin <120 kg: 2 g IV≥120 kg: 3 g IV or
cefuroxime 1.5g or
Vancomycin 15mg/kg (max2 grams)
Or Clindamycin 900mg
PCN: Beta-lactams that interfere with the synthesis of
peptidoglycan, an essential component of the bacterial cell wall. Bacterial cells are therefore unable to maintain the integrity of the cell wall. Eventual the cell wall and the bacterial cell lyses.
Bleeding abnormalities with
ticarcillin, mezlocillin, piperacillin (ex elevated bleeding times, PT) may occur.
Electrolyte abnormalities
Penicillin G K contains
1.7mEq of potassium per 1
million units.
Penicillin G Sodium contains
2mEq of sodium per 1
million units.
1st Generation
Cefazolin* ! Cephalexin*
2nd Generation
Cefotetan(MTT)! Cefuroxime
3rd Generation
Ceftriaxone*
! Ceftazadime*
! Ceftazadime/avibactam*
! Ceftolozone/tazobactam*
4th Generation
! Cefepime*
Prednisone equivalent to cortisol 1
7mg
Cephalosporins: Cross sensitivity with penicillin in
patients with a penicillin allergy reported to be approximately 5%.
Imipenem/Cilastatin
One of the broadest spectrum of any beta lactam
Activity against most gram positive and gram negative organism
Excellent Anaerobic activity
Bleeding abnormalities with has
Cefamandol,
Cefoperazone, and Cefotetan due to
mehtlytetrazolethiol (MTT) side chain.
Been reported to prolong PT and possibly cause bleeding.
! Ceftriaxone
! If bleeding should occur and PT is prolonged, give vitamin K 10mg or FFP.! Packed RBC’s or platelet transfusions may be indicated.
Ceftriaxone Predisposing factors for bleeding include
preexisting renal or hepatic disease.
Less likely to cause seizures than imipenem. Slightly better activity against aerobic GNR than Imipenem.
MEROPENEM
Know Aminoglycosides since they potentiate NMB
Amikacin Gentamycin Neomycin Tobramycin Steptomycin
Drugs that interfere with the synthesis of the mucopeptide layer of the bacterial cell wall are
PCN, Cephalosporins, Vancomycin
Allowing leakage of cell contents, alter permeability of cell membrane
Polymixins
Act on the subunit 30S of the bacterial ribosomees so as the inhibit bacterial protein synthesis at the translational level
Aminoglycosides
Tetracyclines
Inhibit bacterial synthesis of folic acid
Sulfonamides
Act on the 50S subunit of the bacterial ribosomes so the inhibit bacterial protein synthesis at the translational level
Chloramphenicol
Erythromycin
Clindamycin
Only situation to use ethacrynic acid
True sulfanamides allergy
Monobactam
Aztreonam
Aztreonam
Good gram - and NO gram +
These agents are highly water soluble and are therefore not absorbed when given via oral route
Aminoglycosides
Aminoglycosides coverage
Excellent gram - coverage
Minimal gram + coverage
No anaerobic coverage
Nephrotoxicity characterized by a
decrease in creatinine clearance, the presence of casts in urine, a decrease in urine specific gravity, oliguria, and
proteinuria.
! Ototoxicity- Directly related to duration
> 10 days. Concurrent administration of ototoxic drugs.
Neurotoxicity- Aminoglycosides can cause
! IV Calcium can overcome weakness caused by
aminoglycosides.
skeletal weakness.
Aminoglycosides and skeletal weakness
This effect is most likely due to the ability of
aminoglycosides to inhibit the prejunctional release
of acetylcholine, while also decreasing the
postsynaptic sensitivity of the acetylcholine.
Caution of aminoglycosides with patients
Use with caution with Parkinson’s patients, and patients with myasthenia gravis.
Macrolides
Erythromycin
! Clarithromycin (Biaxin®)
! Azithromycin (Zithromax®)
Macrolides activity
Activity against most gram positive organisms, and atypical organisms (Chlamydia pneumonia, Legionella Sp.,
Mycobacterium Sp.)
Clarithromycin and erythromycin
Clarithromycin- Has a longer half life than erythromycin allowing BID dosing
Erythromycin stimulates
GI intolerance (most frequent side effect) Due to stimulation of motlin a gastric hormone that stimulates peristalsis.
Ototoxicity with IV erythromycin
Transient deafness
Cardiac toxicity with erythromycin
Prolongation of QT interval
Drug interactions with macrolides such as erythromycin
Macrolides are inhibitors of hepatic Enzymes
A lincomycin antibiotic
Clindamycin
Clindamycin coverage
with excellent anaerobic coverage, good gram positive
coverage.
Only outlier not cleared by the kidneys but liver
Clindamycin
Clindamycin is useful for prophylaxis in
dental procedures in PCN allergic patients.
Has been reported with the use of clindamycin.
! Severe pneudomembranous colitis
Decrease the dose in patients with severe liver disease
Clindamycin
Chloramphenicol **
! Because of the rare occurrence of aplastic anemia, clinical use of chloramphenicol is limited to severe
infections (typhoid fever, salmonellosis) for which alternative agents may be less effective.
A glycopeptide antibiotic
Vancomycin
Vancomycin MOA
that impairs cell wall synthesis of gram positive organisms.
Vancomycin and activity
has a narrow spectrum of activity, excellent coverage for most gram positive organisms. Has no gram negative coverage.
Should be reserved for treatment of infections due to resistant species.
Vancomycin
Vancomycin must be given IV for
treatment of systemic infections
Vancomycin Oral dosage forms is indicated
for treatment of C. Difficile associated colitis.
Vancomycin should be given over
at least 60 minutes to minimize the histamine release and hypotension associated with rapid infusion rates.
! Such reactions are termed “Red neck or Redman syndrome.
Vancomycin Adverse reactions
! Nephrotoxicity
! Ototoxicity
! Allergic reactions
Vancomycin and NMB
Potentiate NMB effects of succinylcholine
Rhabdo suspects with
Daptomycin
Treatment of SIADH
Demeclomycin
Dilsufiram reaction is
Metronidazole taken with alcohol
Fluoroquinolones advers reactions
Risk of tendon rupture
Most potent at the NMJ
Polymixin
Rarely causes reaction
Bacitracin
