Antibiotic Review

1
Antibiotic Review

• Melissa Parson Pharm.D.
• Clinical Pharmacist
• Sinai Hospital

2
Objectives

• Overview of organisms
• Review of Antibiotics
• Surgical Prophylaxis

3
Review of Organisms

• Dipiro, JT, Talbert RL, Yee GC, Matzke GR, Wells
  BG, Posey LM, editors. Pharmacotherapy. A
  Pathophysiologic Approach. 4th ed. Stamford, CT
  Appleton Lange, 1999 1600.

4
Normal Colonizing Flora

• Dipiro, JT, Talbert RL, Yee GC, Matzke GR, Wells
  BG, Posey LM, editors. Pharmacotherapy. A
  Pathophysiologic Approach. 4th ed. Stamford, CT
  Appleton Lange, 1999 1599.

5
Antibiotic Classes

• Penicillins
• Cephalosporins
• Monobactam
• Carbapenem
• Glycopeptide
• Oxazolidionone

• Aminoglycosides
• Macrolides
• Tetracycline
• Sulfonamide
• Nitroimidazole
• Quinolones

6
Antibiotic Spectrum

• Gilbet DN, Moellering RC, Eliopoulos GM, Sande
  MA. The Sanford Guide to Antimicrobial Therapy
  2006. 36th ed. Sperryville, VA Antimicrobial
  Therapy, INC., 2006 53.

7
Antibiotic Spectrum

• Gilbet DN, Moellering RC, Eliopoulos GM, Sande
  MA. The Sanford Guide to Antimicrobial Therapy
  2006. 36th ed. Sperryville, VA Antimicrobial
  Therapy, INC., 2006 54.

8
Antibiotic Spectrum

• Gilbet DN, Moellering RC, Eliopoulos GM, Sande
  MA. The Sanford Guide to Antimicrobial Therapy
  2006. 36th ed. Sperryville, VA Antimicrobial
  Therapy, INC., 2006 55.

9
Antibiotic Spectrum
10
Vancomycin Dosing Nomogram
11
Vancomycin Nomogram
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Aminoglycoside Dosing

• Pre-Op Dosing 160mg or 240mg
• Post-Op Dosing/ Treatment Dosing
• If CrCl gt 30 ml/min give 5 or 7mg/kg dose
• Random Level 8 hours after infusion
• Pharmacy to follow dosing per TDM Service
• If CrCl lt 30 ml/min contact pharmacy for dosing
• 2-3 mg/kg dose
• 2 random levels to be ordered by pharmacy
• All aminoglycosides monitored by TDM Service

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Sinai Antibiogram
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Therapeutics

• Determine Source/Site of infection
• Identify suspected pathogens
• Choose appropriate therapy based on the above
• Determine duration of therapy

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Surgical Prophylaxis

• Goals
• Selection of antimicrobial agents
• Timing of administration
• Duration of administration

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Goals of Surgical Prophylaxis

• Prevention of post-op infection at surgical site
• Prevention of post-op infections morbidity and
  mortality
• Reduction in duration and cost of health care
• Produce no adverse effects
• Have no adverse consequences for the microbial
  flora of the patient or the hospital

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Goals of Surgical Prophylaxis

• Active against pathogen that is most likely to
  contaminate the wound
• Give at an appropriate dosage and at a time to
  ensure adequate concentrations at the incision
  site during the period of potential contamination
• Safe
• Administered for the shortest effective period to
  minimize adverse effects, development of
  resistance, and cost.

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Goals of Surgical Prophylaxis

• Antibiotic use for Dirty and contaminated
  procedures is not classified as prophylaxis, but
  treatment for presumed infection.
• Prophylaxis typically not indicated for clean
  procedures
• Justified for procedures involving prosthetic
  placement
• Cardiothoracic, GI tract, head and neck,
  neurosurgical, obstetric or gynecologic,
  orthopedic, urologic and vascular

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Selection of Antimicrobial Agents

• Based on cost, adverse-effect profile, ease of
  administration, pharmacokinetic profile, and
  antibacterial activity
• Activity against most common surgical wound
  pathogens
• Clean-contaminated effective against GI/GU
  organisms
• Clean effective against Staph and Strep

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Selection of Antimicrobial Agents
21
Selection of Antibiotics
22
Timing of Antibiotic Prophylaxis

• Delivery of drug to operative site before
  contamination occurs
• Ideal timing is 30 minutes to one hour prior to
  incision (at time of induction of anesthesia)
• Flagyl given 1 hour prior
• Vancomycin given 2 hours prior

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Duration of Antibiotic Prophylaxis

• 24 hours or less
• Cardiothoracic procedures- up to 72 hours
• Coverage must be provided from time of incision
  to closure of incision
• Re-administer if short-acting agent used or
  surgery lasting longer than 6-8 hours
• Re-administer if excessive bleeding or change in
  half-life of drug (i.e. extensive burns)
• May avoid re-administration of half-life is
  extended ( i.e. renal insufficiency)

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Biliary Tract Surgery

• Cholecystetomy, exploration of common bile duct,
  choledochoenterostomy
• Risk of infection 5-20
• Higher risk of infection bacteria in bile,
  obesity, age gt 70, acute episode of cholecystitis
  or cholelithiasis within previous 6 months, DM,
  h/o obstructive jaundice or bile duct obstruction

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Biliary Tract Surgery

• Organisms E.coli, Klebsiella, Enterococci
• Less frequent other gram negative, strep, staph
• Occasionally anaerobes (Clostridium sp.)
• Recommendation
• Single dose of cefazolin at induction of
  anesthesia for open procedures in biliary tract
• No prophylaxis in laparoscopic cholecystectomies

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Appendectomy

• 80 are Uncomplicated (acute inflammation)
• Complicated (perforated or gangrenous
  perotonitis, abcess formation)
• considered infection, not prophylaxis
• 9-30 risk of infection
• Oragnisms anaerobic and aerobic gram-negative
  enteric organisms
• Bacteroides fragilis, E.coli
• Aerobic and anaerobic strep, staph and
  enterococcus

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Appendectomy

• Recommendation
• Cephalosporin with anaerobic and aerobic activity
  at induction of anesthesia
• For PCN allergy metronidazole, gentamicin at
  induction of anesthesia

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Colorectal Surgery

• 30-60 risk of infection (lt10 with prophylaxis)
• Rectal gt intraperitoneal colon resection
• Surgeries gt 3.5 hours
• Host defenses, age gt 60, hypoalbuminemia,
  bacterial contamination of surgical wound,
  steroid therapy, malignancy

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Colorectal Surgery

• Organisms B. fragilis, and other anaerobs
  (1,000-10,000 higher conc. than aerobes), E.coli
• Mechanical bowel preparation
• Neomycin and erythromycin 1gm 19, 18, 9 hours
  before surgery
• aerobic and anaerobic activity (Ancef, Flagyl) at
  induction of anesthesia

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References

• Dipiro, JT, Talbert RL, Yee GC, Matzke GR, Wells
  BG, Posey LM, editors. Pharmacotherapy. A
  Pathophysiologic Approach. 4th ed. Stamford, CT
  Appleton Lange, 1999 1599-1600.
• Gilbet DN, Moellering RC, Eliopoulos GM, Sande
  MA. The Sanford Guide to Antimicrobial Therapy
  2006. 36th ed. Sperryville, VA Antimicrobial
  Therapy, INC., 2006 53-55.
• ASHP Comission on Therapeutics. ASHP Therapeutic
  Guidelines on Antimicrobial Prophylaxis in
  Surgery. Am J Health Syst Pharm 1999 56(18)
  1839-1888.