CLINICAL USE OF ANTIBIOTICS. Prophylactic therapy : Given to patients before contamination or infection has occurredAnticipatory therapy : Includes situations where contamination has already occurred and therapy is aimed at minimizing post-op infectionEmpiric therapy : Non-directed therapy in absence of pathogen identificationDirected therapy : Pathogen identified.
2. CLINICAL USE OF ANTIBIOTICS Prophylactic therapy : Given to patients before contamination or infection has occurred
Anticipatory therapy : Includes situations where contamination has already occurred and therapy is aimed at minimizing post-op infection
Empiric therapy : Non-directed therapy in absence of pathogen identification
Directed therapy : Pathogen identified
3. Surgery associated infection Approximately 60% of patients admitted to the hospital are "surgericed" at some point during their stay in hospital
Depends upon type of surgery, patient risk factors & hospital antimicrobial practices
Estimated to account for up to 70% of nosocomial infections
4. Factors Associated with Increased Risk of Surgical Infection
6. Clean--nontraumatic, uninfected wound; respiratory, gastrointestinal, genitourinary tract or oropharyngeal cavity not entered; elective, primarily closed, undrained wound
Clean-contaminated--respiratory, gastrointestinal, genitourinary tract or oropharyngeal cavity entered without unusual contamination and under controlled conditions; mechanically drained wound
Contaminated--open, fresh traumatic wounds; gross spillage from gastrointestinal tract; major break in sterile technique; acute, nonpurulent inflammation
Dirty/Infected--old traumatic wounds; clinical infection; perforated viscera
9. ANTIBIOTIC PROPHYLAXIS Antibiotic prophylaxis is the peri-operative and/or intra-operative administration of antibiotics to patients to reduce the risk of postoperative infection
10. Antibiotic Prophylaxis Goals The aim of prophylaxis is to augment host defense mechanisms at the time of bacterial invasion, thereby decreasing the size of the inoculum
Use antibiotics in a manner that is supported by evidence of effectiveness
The use of prophylactic antibiotics is an adjunct to and not a substitute for good surgical technique.
11. Antibiotic Prophylaxis Benefits
Decreased incidence of infection (wound/distal)
Reduce overall costs - Prolonged stay
Emergence of resistant bacteria
12. The 6 laws of prophylactic antibiotic administrationIn prevention of surgical infection
13. Law #1
14. Don't start too early, don't start too late
Tissue levels should peak when the knife goes in Law # 2
15. Effect of timing of Prophylactic Antibioticon the infection rate 2847 patients undergoing elective clean or clean-contaminated surgical procedures.
Patients divided into 4 categories based upon timing of administration of antibiotic
Early 2-24 hours before surgery
Pre-operatively 0-2 hours before surgery
Perioperative 0-3 hours after surgery
Post-operative 3-24 hours after surgery
16. Law # 3 Give the right antibiotic An appropriate prophylactic antibiotic should :
(1) Be effective against microorganisms anticipated to cause infection.
(2) Need not eradicate every potential pathogen.
(3) Achieve adequate local tissue levels.
(4) Cause minimal side effects.
(5) Be relatively inexpensive.
(6) Have no adverse effect on the microbial flora of the patient or hospital.
17. Third-generation cephalosporins (Cefotaxime, Ceftriaxone, Cefoperazone, Ceftazidime or Ceftizoxime)
Fourth-generation cephalosporins: e.g. cefepime
Some are less active than 1ST generation against staphylococci
Non-optimal spectrum of action (activity against organisms not commonly encountered in elective surgery)
Widespread use for prophylaxis encourages emergence of resistance
18. Law # 4 give the drug intravenously as oral absorption may be unreliable
The effective dose should be governed by the patient's weight.
e.g Cephalosporin (Cefazolin)
<= 70 kg: 1 g
>70 kg: 2 g
19. Law #5 Use additional intra-operative dose only when necessary:
* long procedures (> 2-3 hours)
* high blood loss (cardiac, liver procedures)
20. Law #6 Keep post-operative doses to a minimum:
* 0 doses adequate for most procedures
* Further doses Up to 48 hours for selected procedures
22. Endogenous Pathogens Commonly Isolated from Postoperative Pelvic Infections Aerobic gram-positive cocci
- Viridans and nongroup A, B, and D streptococci
- Group B streptococci
strept faecalis, Staphylococcus aureus
- Staphylococcus epidermidis
Aerobic gram-negative bacilli
- Escherichia coli
- Klebsiella species
- Proteus mirabilis
- Gardnerella vaginalis
23. Observations in Obgyn surgical infections Febrile morbidity is more common after abdominal than after vaginal hysterectomy
Age has inconsistently been shown to be a risk factor after hysterectomy, with premenopausal women shown to be at increased risk in some studies, especially after vaginal hysterectomy
24. Observations in Obgyn surgical infections Bacterial vaginosis has been associated with an increased risk of infection after abdominal hysterectomy
Patients scheduled for elective hysterectomy should be screened for bacterial vaginosis; one month before the planned procedure. Those found to have bacterial vaginosis should be treated and allowed several weeks to reestablish a normal lactobacillus-dominant flora before surgery
27. ANTIBIOTIC PROPHYLAXIS IN GYNAECOLOGICALSURGERY Clean Procedures : Antibiotic prophylaxis is considered optional for most clean procedures, although it may be indicated for certain patients that fulfill specific risk criteria
Rationale: Likely infecting organism are gram-positive cocci (S. aureus or S. epidermidis) and aerobic coliforms (E. coli).
Agents: Cefazolin, cefuroxime, augmentin or metronidazole.
28. ANTIBIOTIC PROPHYLAXIS IN GYNAECOLOGICALSURGERY Vaginal/abdominal hysterectomy :
. Augmentin 1.2 g single dose
. Cefazolin 1 - 2 g single dose ± Metronidazole 500 mg IV single dose
. Cefuroxime 1.5 g IV single dose ± Metronidazole 500 mg IV single dose
Laparotomy : In high risk patients
Laparoscopy : None
Hysteroscopy : None
29. ANTIBIOTIC PROPHYLAXIS IN GYNAECOLOGICALSURGERY Infertility promoting surgery :
. Augmentin 1.2 g single dose
. Cefazolin 1 - 2 g or Cefuroxime 1.5 g IV single dose ± Metronidazole 500 mg IV single dose
. In salpingostomy for hydrosalpinx; extend prophylaxis up to one week (doxycycline + metronidazole OR Augmentin)
30. ANTIBIOTIC PROPHYLAXIS IN GYNAECOLOGICALSURGERY D&C: missed abortion or induced abortion with risk factors, (e.g. history of previous PID, multiple partners, young, known gonococcal or chlamydia infections)
200 mg Doxycycline one hour before, followed by 100 mg x 2 daily x 4 days
IUCD insertion and HSG with risk factors :
Prohylaxis is probably indicated - Doxycycline as above
31. ANTIBIOTIC PROPHYLAXIS IN OBSTETRIC AND GYNAECOLOGICALSURGERY Penicillin/Cephalosporin
Clindamycin, IV, 150 mg 6 hourly for
2–3 doses may be used for such patients
32. High-risk patients
Ampicillin, 2 g IM or IV, plus gentamicin, 1.5 mg/ kg (not to exceed 120 mg) within 30 minutes of starting the procedure; six hours later, ampicillin, 1 g IM/IV, or amoxicillin, 1 g orally
Patients allergic to ampicllin / amoxicillin
Vancomycin, 1 g IV over 1-2 hours, plus gentamicin, 1.5 mg/ kg IV/IM (not to exceed 120 mg); injection/infusion within 30 minutes of starting the procedure
37. Surgical technique remains the paramount factor in preventing infection, but antibiotic prophylaxis assists the patients host response when some bacterial contamination is inevitable.