Prophylactic Antibiotics Flashcards
What antibiotic is used for prophylaxis before & after surgical procedures?
perioperative cefazolin to prevent SSI
What is the recommendation for prevention & treatment of infections in splenectomized patients?
- influenza immunization
- pneumococcal immunization
- lifelong prophylactic antibiotics
- phenoxymethylpenicillin
- erythromycin
why are preoperative antibiotic prophylaxis administered?
- to decrease risk of postoperative infection
- not substitute for proper aseptic technique
- administered IV
What are the principles of using preoperative antibiotic prophylaxis?
- should be active against common surgical wound pathogens (reserve broad-spectrum antibiotics for therapy resistant infections)
- use shortest possible course
- least expensive
- must achieve concentrations greater than MIC of pathogens
What are the significant components in the prevention of SSI?
- organisms implicated
- timing of administration
- antibiotic selection
- monitoring
- redosing
What are the most important organisms implicated in SSIs?
GRAM +ve
- Staph. aureus
- Staph edpidermidis
GRAM -ve
- E. coli
- pseudomonas
How to determine appropriate antibiotic selection?
achieve narrow spectrum of activity while ensuring most common organisms are covered
What are the most common SSI causing organisms in clean procedures?
SKIN FLORA
- Staph aureus
- Staph epidermidis
What are the organisms found in clean-contaminated SSIs?
Skin flora & gram negative bacteria
When should the prophylactic antibiotic concentration be at its highest?
at the start & during surgery
- at least 30mins before but not more than 60mins before skin incision
When should vancomycin & levofloxacin be administered?
120 mins before skin incision
What should be done for a patient already receiving an antibiotic for another infection before surgery & its suitable for prophylaxis?
give another dose within 60 mins of incision
What is the preoperative antibiotic selection based on?
- cost
- anatomic region
- safety
- ease of administration
- BACTERIOCIDAL
- hospital resistance patterns
What is the activity of clindamycin?
bacteriostatic at lower doses
bacteriocidal at higher doses
What is the aim in surgeries incase of prophylactic antibiotic administration?
reaching the bactericidal concentration in the blood & tissues before skin incision
When are beta-lactam antibiotics contraindicated?
if a patient has an IgE mediated allergy to penicillin
AVOID - penecillins
- cephalosporins
- carbapenems
cephalosporins & carbapenems are considered safe in which patients?
patients who have not had a type-1 reaction or erythroderma
Cefazolin is used for surgical prophylaxis in?
- gram +ive bacteria
- patients with no history of beta-lactam allergy
- no history of MRSA infection
if a patient has a beta-lactam allergy, what are the alternative antibiotics used?
clindamycin
vancomycin
What drug should be used in a patient with high risk for MRSA?
vancomycin
What antibiotics should be used for a patient requiring additional microbe coverage?
cefazolin + metronidazole OR carbapenem
What antibiotic should be used in SSI in a clean wound?
- low risk of MRSA: cefazolin
- high risk of MRSA or allergy to beta-lactam: vancomycin or linezolid
what antibiotic should be used in SSI in a clean-contaminated wound or clean over perineal region?
- cephalosporin + metronidazole or crabapenem
What are the mechanisms of antibiotic resistance?
- production of inactivating enzymes
- decreased drug entry & accumulation
- alteration of target receptor
- development of alternative metabolic pathway
Why is limiting duration of al antibiotics important?
any antimicrobial usage can change hospital & patient bacterial flora leading to colonization resistance or clostridium defficile
What are the 3 antibiotics used where weight-based dosing is recommended?
cefazolin
vancomycin
gentamycin
if there is an increase in resistance of clindamycin, what alternative should be administered?
vancomycin
if there’s an increasing number of carbapenem resistance, what alternative should be administered?
cefoxitin in colorectal surgeries
What are the factors that could affect the half life of a drug?
renal dysfunction & extensive burns
When should redosing be considered?
- if anything is affecting its half-life
- length of procedure
- cefazolin should be readministered 4 hours after
initial dose
- cefoxitin should be administered again 2 hours after
initial dose - if there was significant blood loss or dilution during surgery
How long should weight based dosing administration continue?
- within 1 hour of surgical incision
- 24 hours post-op
When should another dose be administered in a surgery?
- if surgery is longer than 4 hours
- if there’s blood loss over 1.500mL
if a post-op infection occurs, how should it be treated?
- empiric antibiotic therapy immediately
- after detection of organism definitive treatment should be administered according to culture & sensitivity
When should empiric antibiotic therapy be used?
- skin infections: cellulitis, necrotizing fasciitis
- bone/joints: osteomyelitis, septic arthritis
- any cause of sepsis
What are the factors that might affect the success of empiric antibiotic therapy?
- circumstance of infection
- relative contraindications
- site of infection
- PREVIOUS ANTIBIOTIC THERAPY
What are the common antibiotics useful in treatment of post-op infections?
- ceftriaxone or cefotaxime +/- gentamycin
- piperacillin/tazobactam +/- tobramycin
- clindamycin or metronidazole in anaerobic infections
- vancomycin +/- gentamycin for MRA or enterococci
