Surgical Antibiotic

Aymen Almajmaie

What are antibiotics?

• Antibiotics are medicines used to treat infections or diseases caused by bacteria.

• Antibiotics have saved millions of lives since they were first introduced in the 1940s and 1950s.

• However, because they have been overused, many antibiotics are no longer effective against the bacteria they once killed. 

How do antibiotics work?

Antibiotics work by blocking vital processes in bacteria, killing the bacteria, or stopping them from multiplying. This helps the body's natural immune system to fight the bacterial infection.

Classification

Bactericidal Antibiotics: antibiotics works by killing the bacteria and their actions is irreversible.

Bacteriostatic Antibiotics:  bacteriostatic antibiotics inhibit growth or reproduction of bacteria, whose actions is reversible.

Antibiotic Mode Of Action Cellular site of inhibition Bactericidal Antibiotics Bacteriostatic Antibiotics

Cell wall synthesis Penicillin , vancomysin , CEPHALOSPORINS, CARBAPENEMS , MONOBACTAMS

Barrier function of cell Polymyxin B , colistin , amphotericin

Nystatin

membrane protein synthesis in ribosome

Streptomycin , aminoglycoside

Tetracycline , chloramphenicol , erythromycin , clindamycin

DNA replication in chromosome

Griseogulvin

DETERMINANTS OF RATIONAL DOSING

A. Concentration-dependent killing: show a significant increase in the rate of bacterial killing as the concentration of antibiotic increases from 4- to 64-fold the MIC of the drug for the infecting organism including aminoglycosides and daptomycin,

B. Time-dependent (concentration-independent) killing : The clinical efficacy of these antimicrobials is best predicted by the percentage of time that blood concentrations of a drug remain abovethe MIC including β-lactams, glycopeptides, macrolides, clindamycin, andLinezolid

C. Post Antibiotic effect : The PAE is a persistent suppression of microbial growth that occurs after levels of antibiotic have fallen below the MIC. Antimicrobial drugsexhibiting a long PAE (for example, aminoglycosides and fluoroquinolones)often require only one dose per day, particularly against gram-negativebacteria.

CHEMOTHERAPEUTIC SPECTRA

A. Narrow-spectrum antibiotics

B. Extended-spectrum antibioticsC. Broad-spectrum antibiotics

Principles of Antibiotic Therapy

Antimicrobial therapy is a mainstay of the treatment of infections, but widespread overuse and misuse of antibiotics have led to an alarming increase in MDR pathogens.

New agents may allow shorter courses of therapy and prophylaxis,

Effective therapy with no toxicity requires a careful but expeditious search for the source of infection and an understanding of the principlesof PK

Evaluation of Possible Infection

Absent a fever, any hypotension, tachycardia, tachypnea, confusion,rigors, skin lesions, respiratory manifestations, oliguria,lactic acidosis, leukocytosis, leukopenia, immature neutrophils or thrombocytopenia may indicate a workupfor infection and immediate empirical therapy.

some cases, new temperature elevation is usually the trigger for an evaluation for the presence of infection

Thermoregulatory mechanisms can be disrupted by drugs or by injury to the central nervous system.

However, some infected patients do not become febrile and may be even be hypothermic. Hypothermic or euthermic patients may have a life-threatening infection. These include older patients, those with open abdominal wounds, or with end-stage liver disease or chronic renal failure, and patients taking anti-inflammatory or antipyretic drugs.

Empirical Antibiotic TherapyEmpirical antibiotic therapy must be administered judiciously.

failure to treat MDRpathogens) leads unequivocally to increased mortality

Empirical antibiotic therapy should usually be stopped after no more than48 to 72 hours.

Factors Influencing Antibiotic Choice

Activity against known/suspected pathogens Disease believed responsibleDistinguish infection from colonizationNarrow-spectrum coverage most desirableAntimicrobial resistance patternsPatient-specific factors• Severity of illness (?)• Age (?)• Immunosuppression• Organ dysfunction• AllergyInstitutional guidelines/restrictions

Antibacterial A gents for Empirical Use

AntipseudomonalPiperacillin-tazobactamCefepime, ceftazidimeImipenem-cilastatin, meropenem, doripenem? Ciprofloxacin, levofloxacin (depending on local susceptibilitypatterns)AminoglycosidesPolymyxins (polymyxin B, colistin [polymyxin E])Targeted-spectrumGram-positiveGlycopeptide (e.g., vancomycin, telavancin)Lipopeptide (e.g., daptomycin; not for known/suspectedpneumonia)Oxazolidinone (e.g., linezolid)

Gram-negativeThird-generation cephalosporin (not ceftriaxone)MonobactamPolymyxins (polymyxin B, colistin [polymyxin E])AntianaerobicMetronidazoleBroad-SpectrumPiperacillin-tazobactamCarbapenemsFluoroquinolones (depending on local susceptibility patterns)Tigecycline (plus an antipseudomonal agent)

AntianaerobicMetronidazoleCarbapenemsβ-lactam and β-lactamase combination agentsTigecyclineAnti-MRSACeftarolineDaptomycin (not for use against pneumonia)Minocycline (oral only)LinezolidTelavancinTigecycline (not in pregnancy or for children under the age ofeight years)Vancomycin

Cardiovascular and thoracic

Prophylaxis for Selected Types of Surgery

Median sternotomyPacemaker insertionVascular reconstruction involving abdominal aorta, insertion of prosthesis, or groin incision (except carotid endarterectomy, which requires no prophylaxis) Implantable defibrillator Pulmonary resection

Clindamycin (for all cardiovascular and thoracic cases except amputation)

Cardiovascular and thoracic

Lower limb amputation

Gentamicin and metronidazole

GeneralCholecystectomy (high risk only) Gastrectomy (high risk only; not uncomplicated chronic duodenal ulcer) HepatobiliaryMajor débridement of traumatic wound Genitourinary

Ciprofloxacin(ampicillin plus gentamicin is a reasonable alternative)

Gentamicin

Gentamicin and metronidazole

Gentamicin

Gynecologic

Cesarean section (STAT )

Hysterectomy (cefoxitin is a reasonable alternative)

Metronidazole or doxycycline, after cord clamping

Doxycycline

Head and neck, oral cavity

Major procedures entering oral cavity or pharynx

Neurosurgery

• Craniotomy

Orthopedics• Major joint arthroplasty• Open reduction of closed fracture

• Appendectomy • Colon surgery• Surgery for penetrating abdominal trauma