Antibiotics are commonly used in surgery both for prophylaxis and treatment of infection. For prophylaxis, antibiotics are administered before incision to prevent anticipated infection, usually as a single pre-operative dose. The choice of antibiotic depends on the surgical procedure and most likely pathogens. For treatment of existing infection, culture and sensitivity testing guides antibiotic selection; empirical broad-spectrum therapy may be initially used. Therapeutic antibiotics should be tailored based on response and culture results and given long enough to cure the infection without promoting resistance. Proper antibiotic usage and completion of a full course are important to optimize outcomes and minimize resistance.

2. ANTIBIOTICS IN
SURGERY
PRESENTED BY-
DR. NESAR AHMAD
MODERATOR-
DR. SIMEEN USMANI
D/O JARAHAT, AKTC, AMU

3. ANTIBIOTICS
• Antibiotic is any substance of natural, synthetic or
semi-synthetic origin which kill (bactericidal) or
inhibit (bacteriostatic) the growth of bacteria

4. NORMAL FLORA

5. Group/mechanism of Action
1- Cell wall synthesis inhibitors
(inh. Peptidoglycan synthesis)
B-lactam- Penicillins/Cephalosporins
others- vancomycin/ bacitracin
2- cause leakage from cell
membranes
Polypeptides- polymyxins
Colistin, Bacitracin
3- Protein synthesis inhibitors
(interfere with 50s or 30s of rRNA)
Tetracyclines , Aminoglycoside ,
Macrolides, chloramphenicol
clindamycin
4- Folate Antagonists
Inhibitor folate synthesis or
reduction
e.g. Sulphonamides,
Trimethoprim
5- DNA gyrase inhibitors Fluoroquinolones e.g.
ciprofloxacin, levofloxacin
6- Nitroimidazole e.g. metronidazole
7-RNA polymerase inhibitor e.g. Rifampicin

8. Mode of action
Bacteriostatic
• Chloramphenicol
• Tetracyclines
• Macrolides
• Sulphonamides
• Clindamycin
Bactericidal
• Penicillins,
• Aminoglycosides
• Cephalosporins
• Metronidazole
• quinolones

9. Principles of Antibiotics in
Surgery
• Indication (prophylaxis vs. therapeutic)
• Susceptibility vs. empirical
• Pharmacodynamics
• Pharmacokinetic
• Combination
• Cost
• Availability
• Monitoring

10. Antibiotics Prophylaxis in Surgery
• use of antibiotic to prevent anticipated infection.
• Single dose regime, based on the most common
organism, which is given at the time of induction to
ensure the minimum inhibitory concentration during
skin incision – reduces risk of surgical site infection
(SSI) and post op infection

11. • Usually a single dose is sufficient. A second dose may
be required in the following situations:
a. in prolonged operations or when there is
excessive blood loss
b. when there is contamination during operation
• Giving more than 1 or 2 doses postoperatively is
generally not advised.

12. • Prophylaxis is generally recommended for clean
contaminated and contaminated operations
• In clean operation prophylaxis is also indicated under
certain conditions i.e. where there is prosthesis
implanted, high risk perforation where infection is
catastrophic e.g. neurosurgery or cardiac surgery.

13. Indications for prophylaxis in
surgery
• Wounds
- Clean contaminated and contaminated wound
- Clean wound in which implants or prosthesis are inserted
- Animal or Human bite
- Open fracture
- Foot/ Hand wounds
- Wound length > 5cm
- Crush
- Wound involving body cavity/ perineum
- Immuno-suppressed patient
- Burns

14. Classification of Surgical Wound

15. Choice of antibiotic
• The choice of the antibiotic for prophylaxis is based on
several factors.
• Always ask the patient about a prior history of antibiotic
allergy, as beta-lactams are the commonest type of
antibiotics used in prophylaxis.
• A history of severe penicillin allergy (anaphylaxis,
angioedema) means that cephalosporins are also
contraindicated, as there is a small but significant risk of
crossreaction.

16. •It is important to select an antibiotic with the narrowest
antibacterial spectrum required, to reduce the emergence
of multi-resistant pathogens and also because broad
spectrum antibiotics may be required later if the patient
develops serious sepsis.
• The use of 'third generation' cephalosporins such as
ceftriaxone and cefotaxime should therefore be avoided in
surgical prophylaxis.
• Often several antibiotics are equal in terms of antibacterial
spectrum, efficacy, toxicity, and ease of administration If
so, the least expensive drug should be chosen

17. • Commonly used surgical prophylactic antibiotics
include:
• intravenous 'first generation' cephalosporins -
cephazolin or cephalothin
• intravenous gentamicin
• intravenous or rectal metronidazole (if anaerobic
infection is likely)
• oral tinidazole (if anaerobic infection is likely)
• intravenous flucloxacillin (if methicillin-susceptible
staphylococcal infection is likely)
• intravenous vancomycin (if methicillin-resistant
staphylococcal infection is likely).

18. GUIDELINES FOR SURGICAL
PROPHYLACTIC ANTIBIOTICS
PROCEDURE SUGGESTED ANTIBIOTIC
1. GI surgery
2. HBS surgery
IV Cefoperazone 1g PLUS IV
Metronidazole 500mg
1. Hernia repair with mesh
(includes laparoscopic repair)
2. Breast
(not recommended for minor excision)
3.Burns
IV Cloxacillin 1g
Vascular Operation IV Ampicillin/Sulbactam 1.5g
Neurosurgery IV Ceftriaxone 1g AND
IV Metronidazole 500mg
Urogenital IV Amoxycillin / clavulanate 1.2g

19. Route and timing of antibiotic
administration
• Oral or rectal antibiotics need to be given earlier to ensure
adequate tissue concentrations during surgery.
• Metronidazole suppositories are commonly used in bowel surgery
and must be given 2-4 hours before it begins.
• Topical antibiotics are not recommended, with the exceptions of
ophthalmic or burns surgery.
• Prophylactic antibiotics are usually given intravenously as a bolus on
induction of anaesthesia to ensure adequate tissue concentrations
at the time of surgical incision.
• Intramuscular antibiotics are less commonly used than intravenous
antibiotics. They are typically given at the time of pre-medication so
that peak tissue levels are attained at the most critical time, the
time of surgical incision.

20. Therapeutic Antibiotics
Therapeutic antibiotics is given to fight infection
that is already established.

21. 1. Establish a Clinical Diagnosis and the need for Antibiotics base
on history and physical examination
2. Determine the Urgency of the situation
•Non-urgent situation: mild infection or chronic infection
•Urgent situation:- Suspected severe infection
3. Obtain an appropriate clinical specimens for examination, culture
and sensitivity
4. Remove barrier to cure by
- Debridement
- sequestrectomy
- I & D
- Good wound care

22. 5. Determine the most likely organism causing the
infection
6. If multiple antibiotics are available to treat
pathogen,
choose the best agent
Prior antibiotic allergies
Antibiotic penetration
Potential side effects
Medical condition of the patient
7- Antibiotic combination can be considered to achieve
Synergism

23. 8. Assess effectiveness of antibiotic therapy
- Clinical assessment –
↓ temperature - 48 hrs for BC antibiotics
3 - 4days for BS drugs
- Inflammatory markers – signif. ↓CRP < 25 % from the baseline
within 24 hrs.
- Contagiousness of patient –
BC 24 hrs.
BS 5 days
9. Initial therapy may need modification after culture results are
available
Modification not necessary if there is significant Relief of
symptoms
Narrow spectrum of antibiotics should be used (to decrease the
risk of colonization)

24. Therapeutic
Antibiotics:
PRINCIPLES
C&S
Combination Pharmaco-
dynamics
Host status
Prevent
resistance
Multiple
pathogens
Site of
infection
Synergism/
Additive
therapy

25. Definitive
Specific to organism
isolated in C & S
Empirical
Initiation of treatment prior
to determination of a firm
diagnosis
THERAPEUTIC
ANTIBIOTICS

26. EMPIRIC THERAPY
• When to start ?
• Risk of surgical infection is high - based on the underlying
disease process (e.g. perforated appendicitis) [prophylaxis
empiric]
• Significant contamination during surgery has occurred (e.g.
considerable spillage of colon contents)
• In critically ill patients – potential site of infection has been
identified
• Severe sepsis or septic shock
• Short course (3-5 days)
• Stop if the presence of a local site or systemic infection is not
revealed

27. Systemic Inflammatory Response
Syndrome (SIRS)
• Empiric antibiotics are not indicated for all
patients with SIRS
• Indications for antibiotic therapy include the
following:
• Suspected or diagnosed infectious etiology (e.g.
UTI, pneumonia, cellulitis)
• Neutropenia or other immunocompromised
states
• Asplenia - Due to the potential for
overwhelming postsplenectomy infection

28. • Abdominal trauma – 3rd generation
Cephalosporins, Cefuroxime, Augmentin, Unasyn
• Perforated viscus, Peritonitis - 3rd generation
Cephalosporins & Flagyl
• Breast abscess (S. aureus) – Cloxacillin
• Mycotic pseudoaneurysm – Cloxacillin
• Prostethic graft infection - 3rd generation
Cephalosporins
• MRSA - Vancomycin

29. DURATION OF THERAPY
• Duration should be long enough to prevent relapse yet
not excessive, as it can increase side effects and
resistance
• Factors such as decreasing trend of WBCs and lack of
fever guide the length of therapy
• The search for extra abdominal source of infection or a
residual /ongoing source of intra abdominal infection
should be sought

30. DURATION OF THERAPY
• Penetrating GI trauma without extensive contamination
• 12-24hours
• Perforated/gangrenous appendicitis
• 3-5days
• Peritoneal soilage due to perforated viscus with
moderate degrees of contamination
• 5-7days
• Extensive peritoneal soilage/immunocompromised host
• 7-14days

31. SIDE EFFECTS/TOXICITY
Antibiotic Side Effects
Penicillins • Allergy , diarrhoea
Cephalosporins • Allergy, thrombophlebitis
Aminoglycosides • Hearing loss
• Vertigo
• Renal dysfunction
Carbapenems • Seizures (Imipenem)
• Rashes
Macrolides • Prolonged QT interval
(Erythromycin)
• Hearing loss, • Jaundice
Clindamycin Diarrhoa/ rash
levofloxacin headache, dizziness or
lightheadedness.

32. ANTIBIOTIC RESISTANCE
• Resistance of a microorganism to an antimicrobial
agent to which it was previously sensitive
• Resistant organisms are able to withstand attack by
antimicrobial medicines so that standard treatments
become ineffective and infections persist and may
spread to others

33. ANTIBIOTIC RESISTANCE
Intrinsic/Natural resistance -
• Drug target is not present in the bacteria’s metabolic
pathways
e.g. Gram –ve bacilli are normally unaffected by
Penicillin G
Acquired resistance -
• Mutation – is a stable and heritable genetic change that
occurs spontaneously and randomly among
microorganisms
• Gene transfer (infectious resistance) - Transfer of genetic
material from resistant to susceptible organisms
(plasmids, bacteriophages)

34. Main factors contributing to resistance are:
• Excess antibiotic usage
• Incorrect use of broad spectrum agents
• Incorrect dosing
• Non compliance

35. Prevention of Drug resistance
1. No indiscreminate and inediquate or unduly
prolonged use of antibiotics should be made
2. Prefer rapidly acting and selective antibiotics
whenever possible
3. Use combination of antibiotics whenever prolonged
therapy is undertaken e.g. TB, HIV-AIDS
4. Infection by organisms notorious for developing
resistance, e.g. Staph.aureus, E.coli, M.Tuberculosis,
Proteus etc. must be treated

36. Common pathogens antibiotic
susceptibility
 SSI for a skin wound at any site:
1. Staph aureus - 90% remains sensitive to flucloxacillin,
macrolides and clindamycin.
2. Beta haemolytic streptococci - 90% remains sensitive to
penicillin, macrolides and clindamycin
 Head and neck surgery:
Oral anaerobes - 95% remains sensitive to metronidazole
and co-amoxyclav

37. Operations below the waist:
1. Anaerobes - 95% remains sensitive to metronidazole
and co-amoxyclav
2. E. coli and other entrobacteriaceae - Complex
resistance, but 90% remains sensitive to second
generation cephalosporins, gentamicin or beta lactam.
Insertion of prosthesis, graft or shunt:
1. Coagulase negative Staph - 90% remains sensitive to
flucloxacillin, clindamycin or microlides.
2. Staph aureus - 2/3 are MRSA but beta lactam
antibiotics are still appropriate.

38. Conclusion
• Prophylactic antibiotic should be given in clean
surgery which involves prosthetic implants, in clean-
contaminated and contaminated surgeries
• Prophylactic antibiotics should be administered within
1 hour prior to incision
• Therapeutic antibiotic should be started for dirty
wound
• Empirical therapy should be altered according to the
sensitivity of the culture
• Escalation and de-escalation of antibiotics should be
done based on clinical response and aided by culture
and sensitivity results

39. • Therapeutic drug monitoring is done in antibiotics
with narrow therapeutic range (Amikacin, Gentamycin,
Vancomycin)
• Allergic reactions include anaphylaxis, fever, rashes,
nephritis, granulocytopenia & hemolytic anemia are
possible side effects of Penicillins and Cephalosporins
• Appropriate choice of antibiotics, dosage, compliance
should be ensured to avoid emergence of resistance

40. Thanks all for
listening