Antibiotics Flashcards
What is the antibiotic prophylaxis for scheduled c-sections?
2g Cefazolin
Consider 1g in pt <80kg
3g in pt >120kg (no clear benefit in reduction in SSI but based on MIC studies)
Within 60 minutes
What does pre-csection vaginal prep benefit?
Decreased endometritis and postoperative fever, esp in patients who are ruptured or laboring. No decrease in surgical wound infections.
What is the downside of prophylactic antibiotics for GBS in obstetrics?
Increases in E Coli sepsis primarily in preterm and low birth weight infants.
Increase in GBS resistance
What is the single biggest risk factor for postpartum infection?
Cesarean delivery
What are options for treatment of post-partum endometritis?
Unasyn 3g IV q6h Gent IV q8 (dosing 80mg-150mg by weight) + clindamycin 99mg IV q8 Vancomyci q8h (febrile through gent/clinda)
What is the treatment for intra-amnionitic infection (chorioamniotis) diagnosed before delivery?
1 dose of post-partum antibiotics (Unasyn or Gent/Clinda)
What are the pharmacokinetics of antibiotics in pregnancy?
Decreased plasma concentration due to:
- increase in GFR > decreased half life
- Increased plasma volume > increased volume of distribution
- Hormone mediated increase in binding proteins
- Decreased gastric emptying
What is the impact of prophylactic antibiotics before cesarean section?
Reduction in post-partum endometritis, nearly 60%. Even with term prelabor cesarean delivery.
What is the benefit of adjunctive azithromycin prophylaxis in c-section?
Reduction in endometritis, wound infection, or other infections (50% reduction, NNT 17).
No RCT in elective cesarean delivery, therefore only used in non-elective cesarean
What are indications to re-dose antibiotics during a c-section?
Surgical time >2 half-lives of the antibiotic (4hrs for cefazolin)
EBL >1500cc
When are latency antibiotics indicated?
Pre-term pre-labor rupture of membranes less than 34w
When fetal lung maturity is not documented and delivery is not imminent
NOT preterm labor with intact membranes
NOT >34w (deliver!)
What does ACOG recommend for latency antibiotic regimen?
2 days IV ampicillin/erythromycin
5 day course oral amoxicillin/ erythromycin
Can substitute azithromycin
Should you use antibiotics for latency in preterm labor?
No! No benefit. Possible long-term harm (functional impairment in infancy, however no difference at 11 years)
When should you consider antibiotic prophylaxis for endocarditis on L&D?
Patients who have:
- cyanotic cardiac disease (unrepaired cyanotic CHD, palliative shunt)
- prosthetic valves/device
- prior infective endocarditis
- cardiac transplant patients structurally abnormal valve with valve regurgitation
NOT mitral valve prolapse
“Consider” - based on highest risk. Primarily for undergoing dental procedures, but can consider on L&D
What antibiotic prophylaxis is given for 3rd of 4th degree lacs?
Single dose of cefotetan or cefoxitin (or clindamycin if PCN allergic)
Protective against wound complications (70% wound infection reduction)
Is antibiotic prophylaxis indicated for cerclage?
Practice bulletin says “insufficient evidence”
May be associated with increased latency time >28 days.
No indication for abdominal cerclage.
At DH:
- cefotetan 2g IV for ultrasound-indicated cerclage, exam-indicated or rescue cerclage
- plus bacitracin lavage for rescue/exam indicated cerclage
Is antibiotic prophylaxis indicated for manual removal/D&C/Bakri?
No data. However studied increased risk of post-partum endometritis.
Commonly use cefotetan x1
What is the microbiology of intra-amniotic infection?
Upward migration of vaginal flora.
Polymicrobial - Ureaplasma, Mycoplasma, Anaerobes, GNR, GBS.
Genital mycoplasma most commonly detected in culture
What are risk factors for IAI?
Long length of labor
Length of rupture of membranes
Others: multiple SVE after ROM, nulliparity, mec stained fluid, STI, GBS, BV, internal monitoring
Diagnostic criteria for chorioamnionitis
Fever (>39 or >38 sustained 30 minutes apart) AND FHR tachycardia Maternal WBC >15 Purulent fluid from os
ACOG suggests isolated fever >39 without clear source can be managed as chorio
Confirmed diagnosis only by gram stain, culture, histopathology
What is the antibiotic treatment for chorioamnionitis?
Unasyn (amp-sulbactam)
Amp/Gent
Cefoxitin / Cefotetan
When do we screen for GBS?
universal GBS screening between 36 0/7 and 37 6/7 weeks of gestation.
How long are GBS tests good for?
5 weeks
When does a GBS positive patient not need prophylaxis?
Cesarean section that is pre-labor and pre-rupture of membranes
When are antibiotics given in GBS unknown?
<37w gestational age
GBS positive in prior pregnancy
Maternal temp
Rupture > 18 hours
What are indications for GBS prophylaxis?
+ GBS rectovaginal swab
GBS bacteriuria any time in pregnancy
h/o neonate with GBS sepsis
How do we treat GBS bacteriuria?
If >105 CFU/mL - treat urinary infection and abx prophylaxis
If <105 CFU/mL - don’t treat urinary infx, do give abx prophylaxis
What antibiotics are primarily used for GBS?
PCN G, 5mil IV then 2.5-3 million q4hr.
Ampicillin 2g IV then 1g q4h
How do we do prophylaxis for GBS in PCN allergic patient?
Cefazolin 2g (if low risk reaction)
Clindamycin 900mg IV q8h
Vancomycin 20mg/kg q8h (if clinda-resistant)
