Antibiotics in ENT Surgery

1. Antibiotics in ENT Surgery Magdy M. Amin RIAD Professor of Otolaryngology. Ain shames University Senior Lecturer in Otolaryngology University of Dundee

2. Prophylactic antibiotics • Prophylaxis with antibiotics has decreased the high incidence of wound infection after head and neck operations that involve incisions through oral or pharyngeal mucosa. • Prophylactic administration of antibiotics can decrease postoperative morbidity, shorten hospitalization, and reduce overall costs attributable to infections.

3. Prophylactic antibiotics • Many antibiotics require a single dose given within 30 minutes of skin incision to provide adequate tissue concentration throughout the operation. • Additional doses during the procedure are advisable if surgery is prolonged (i. e, >4 h), major blood loss occurs, or an antimicrobial with a short half-life is used

4. The aim of prophylaxis • The aim of prophylaxis is to augment host defense mechanisms at the time of bacterial invasion,. • Prophylaxis is an attempt to attack organisms before they have a chance to induce infection. • Previous surgery (i. e, scarring) and radiation injury decrease host defenses. • Likewise, certain medical conditions, such as diabetes mellitus or HIV, predispose the patient to infection because of diminished host response.

5. Choosing an antibiotic for prophylaxis Choosing an antibiotic for prophylaxis is multi-factorial and should be based on the following: • Type of operation • Kinetics and toxicity of the drugs • Microbiologic characteristics of the operative site • Antibiotic sensitivities specific to the particular hospital environment

6. Choosing an antibiotic for prophylaxis • If a number of drugs appear equally acceptable for prophylaxis, the agent least likely to be used for definitive therapy in postoperative wound infection should be chosen. • This strategy should minimize the selection of organisms resistant to valuable therapeutic agents.

7. Choosing an antibiotic for prophylaxis • The regimen chosen should be compatible with findings from the hospital's infection control wound surveillance report. • This regimen is particularly important in hospitals with high incidence of infection with methicillin-resistant organisms (eg, S aureus [MRSA], S epidermidis [MRSE]) or with newly vancomycin-resistant organisms.

8. CLASSIFICATION OF OPERATIONClass Definition • Clean Operations in which no inflammation is encountered . The respiratory, alimentary or genitourinary tracts are not entered. There is no break in aseptic operating theatre technique.

9. Non contaminated head and neck surgery • Non contaminated surgery refers to violation of prepared skin only and no mucosal exposure or incision (eg, neck dissection, parotidectomy, thyroidectomy).

10. Non contaminated head and neck surgery • Clean surgical procedures are those in which no infection exists prior to surgery. • During surgery, sterility of the wound is maintained. • Following closure of the wound at completion of surgery, the wound is never again exposed to direct contact with bacteria. • The risk of postoperative wound infection under these circumstances is less than 5%.

11. CLASSIFICATION OF OPERATIONClass Definition Clean-contaminated Operations in which the respiratory, alimentary or genitourinary tracts are entered but without significant spillage.

12. CLASSIFICATION OF OPERATIONClass Definition Contaminated Operations where acute inflammation (without pus) is encountered. or where there is visible contamination of the wound. Examples include gross spillage from a hollow viscus during the operation or compound/open injuries operated on within four hours.

13. CLASSIFICATION OF OPERATIONClass Definition Dirty Operations: In the presence of pus. where there is a previously perforated hollow viscus, or compound/open injuries more than four hours old.

14. PROBABILITY OF WOUND INFECTION BY TYPE OF WOUND AND RISK INDEX Risk Index 0 1 2 Clean 1.0% 2.3% 5.4% Clean-contam. 2.1% 4.0% 9.5% Contaminated 3.4% 6.8% 13.2%

15. ENT SURGERY • Head and neck surgery - A Antibiotic prophylaxis is recommended • Head and neck surgery - clean C Antibiotic prophylaxis is not recommended There is no evidence of effectiveness from RCTs • Ear surgery - clean A Antibiotic prophylaxis is not recommended There is no evidence of effectiveness from RCTs • Nose or sinus surgery C Antibiotic prophylaxis is not recommended There is evidence of no effectiveness from RCTs • Tonsillectomy C Antibiotic prophylaxis is not recommended There is no evidence of effectiveness of prophylaxis from RCTs. The cited trials are of treatment for seven days after tonsillectomy, not prophylaxis.

16. ADMINISTRATION OF INTRAVENOUS PROPHYLACTIC ANTIBIOTICS Prophylaxis should be started preoperatively in most circumstances ideally within 30 minutes of the induction of anesthesia.

17. ADMINISTRATION OF INTRAVENOUS PROPHYLACTIC ANTIBIOTICS Antibiotic prophylaxis should be administered immediately before or during a procedure. Prophylactic antibiotics should be administered intravenously. The single dose of antibiotic for prophylactic use is, in most circumstances, the same as would be used therapeutically.

18. ADMINISTRATION OF INTRAVENOUS PROPHYLACTIC ANTIBIOTICS An additional dose of prophylactic agent is not indicated in adults, unless there is blood loss of up to 1500 ml during surgery or haemodilution of up to 15 ml/kg. Fluid replacement bags should not be primed with prophylactic antibiotics because of the potential risk of contamination and calculation errors.

19. Duration of Perioperative Antibiotic Use 1. Prophylactic perioperative antibiotics should be started prior to skin incision for maximal benefit.

20. Duration of Perioperative Antibiotic Use 2. There is no advantage to continuation of perioperative antibiotics beyond 24 to 48 hours postoperatively has ever been demonstrated.

21. Duration of Perioperative Antibiotic Use The possible exception to this is metronidazole; • because metronidazole may enter abscess spaces better than other antibiotics. • its prolonged use has been associated with less severe postoperative infections in one study.

22. Prophylactic Antibiotic Regimens for Major Clean-Contaminated • Clindamycin: 600 mg IV within 1 hour of surgery, 4 additional doses Q6H following surgery. The antibiotic may alternatively be given for a full 48 hours postoperatively. there is no compelling evidence that the additional 24 hours confers any additional benefit.

23. Prophylactic Antibiotic Regimens for Major Clean-Contaminated 2. Augmentine: 1.5 grams IV within 1 hour of surgery . and 8 additional doses at 6-hour intervals following surgery.

24. Prophylactic Antibiotic Regimens for Major Clean-Contaminated 3. Cefazolin: 2.0 grams IV within 1 hour of surgery. and 3 postoperative doses at 8-hour intervals. This regimen may be extended to a total of 48 hours postoperatively.

25. Prophylactic Antibiotic Regimens for Major Clean-Contaminated 4. Cefazolin/metronidazole: cefazolin 1 gm IV 1 hour prior to surgery then 1 gram IV every 8 hours postoperatively for a total of 6 doses. and metronidazole 900 mg IV 1 hour prior to surgery then 900 mg IV every 8 hours postoperatively for a total of 6 doses.

26. ENT SURGERYAntibiotic prophylaxis is recommended in: • A – Head and neck surgery (clean-contaminated/contaminated) • Antibiotic prophylaxis is not recommended in: • A – Ear surgery (clean) • C – Head and neck surgery (clean) • C – Nose or sinus surgery • C – Tonsillectomy

27. Contaminated head and neck surgery • Contaminated surgery refers to transmucosal operations (eg, composite resection, glossectomy, maxillectomy). • Saliva contains 108 bacteria per milliliter, 90% of which are anaerobic. Ninety-six percent of wound infections in the head and neck are polymicrobial.

28. Contaminated head and neck surgery • Organisms involving oropharyngeal flora included: • anaerobic organisms (Bacteroides, 76%) • gram-negative rods (eg, Escherichia coli and Klebsiella, Serratia, and Proteus species) • gram-positive organisms (ie, Staphylococcus, Streptococcus).

29. Contaminated head and neck surgery • Clindamycin (600 mg PO/IV q8h for 4 doses) is the recommended antibiotic to prevent anaerobic wound contamination in extensive surgeries of the head and neck. • Appropriate antibiotic choices also include a combination of ampicillin and sulbactam (3 g IV followed by 1.5 g q8h for 3 doses) • combination Ancef and Flagyl. • As an oral mouth rinse, use of clindamycin (75-mg caps stirred in 8 oz of tap water) or chlorhexidine (Peridex) provides rapid and sustained reductions in the concentrations of aerobic and anaerobic oral flora.

30. Facial fractures • Open fractures have an increased incidence of infection in the absence of antibiotic prophylaxis when compared to closed or open fractures treated with prophylactic antibiotics.

31. Facial fractures • Antibiotic prophylaxis significantly reduce the incidence of postoperative infections in facial fractures, especially mandible fractures of the body. • The infection rates in zygoma fractures, LeFort fractures, and mandibular subcondylar fractures are similar.

32. Disadvantages of antibiotics • It promotes antibiotic resistance and contributes to super infection. • Antibiotic use is also costly and associated with allergic reactions, toxic reactions, and adverse effects • The use of antibiotics may encourage laxity of good surgical technique.

35. Penicillin • Mechanism of action • Exerts action on actively dividing cells by causing abnormal cell wall development • Inhibits third stage of cell wall synthesis • Resistance • Alterations in penicillin-binding proteins • Inability to penetrate bacterial cell walls • Enzymatic hydrolysis of penicillin molecule

36. Penicillin • Spectrum • Gram-positive cocci - Group A and group B Streptococcus • Gram-positive bacilli - Corynebacterium diphtheriae • Gram-negative cocci - Neisseria meningitidis • Gram-negative bacilli - Streptobacillus moniliformis • Anaerobes - Clostridium, Bacteroides, Fusobacterium, and Peptostreptococcus species • Miscellaneous - Treponema pallidum and Leptospira, Enterobacter, and Acinetobacter species

37. Penicillin • Adverse reactions • Hypersensitivity (1-5%) • Irritant properties that affect the peripheral nervous system • Nephropathy - Allergic reaction manifested by interstitial nephritis and hypokalemia

38. Cephalosporin • Mechanism of action • Inhibits third step of bacterial wall synthesis • Binds to specific proteins on cell membranes • Alters cell permeability • Inhibits protein synthesis • Releases autolysins • Resistance - Decrease in bacterial cell wall permeability to antibiotics and production of beta-lactamase

39. Cephalosporin • Spectrum • First generation (eg, Ancef, Keflin, Kefzol) - Have the greatest degree of activity against gram-positive organisms, such as Staphylococcus and Streptococcus (not MRSA); have the same coverage against gram-positive, anaerobic, and aerobic bacilli as penicillin • Second generation (eg, Ceclor, Zinacef, Mefoxin) - Less active against gram-positive bacteria, but have an advantage against Haemophilus influenzae organisms and some gram-negative bacilli, including Proteus and Enterobacter species • Third generation (eg, Ceftazidime, Cefotaxime, Cefoperazone) - Have the greatest activity against gram-negative aerobes, with variable activity against Pseudomonas organisms

40. Cephalosporin • Adverse reactions • Hypersensitivity - Highest incidence in those allergic to penicillin • Hematologic - Neutropenia, leukopenia, and thrombopenia • GI disturbances - Nausea, vomiting, anorexia, and diarrhea • Reversible renal impairment

41. Erythromycin • Mechanism of action - Inhibits bacterial protein synthesis • Resistance • Alteration in protein component of 50s ribosomal subunit • Plasmid-mediated resistance

42. Erythromycin • Spectrum • Similar to that of penicillin G • Effective against Mycoplasma, Legionella, and Actinomyces species • Combined with sulfisoxazole to make Pediazole, which is used in the pediatric population • Effective against H influenzae organisms • Adverse reactions • GI disturbances • Hypersensitivity • Cholestatic hepatitis

43. Clindamycin • Mechanism of action: Binds to 50s ribosomal subunit, thereby inhibiting protein synthesis • Resistance: Similar to that of erythromycin

44. Clindamycin • Spectrum • Active against most aerobic and anaerobic gram-positive organisms • Anaerobic gram-negative organisms • although some staphylococcal organisms have developed resistance

45. Clindamycin • Adverse reactions • Pseudomembranous colitis • Mild nausea and diarrhea • Hypersensitivity • Leukopenia Transient increase • Hepatotoxicity (rare)

46. Metronidazole (Flagyl) • Mechanism of action • Reduced intracellularly to its active metabolite that is bactericidal • May be administered orally, intravenously, or rectally • Metabolized in the liver and excreted by the kidneys

47. Metronidazole (Flagyl) • Adverse reactions (most of which are dose related and are not seen with regular short-term use) • CNS toxicity • GI disturbance • Neutropenia • Drug fever • Synergistic alcohol effect • Prolonged activated partial thromboplastin time (aPTT)