Antibiotics exam 1 Flashcards
In doctor’s offices antibiotics have been over prescribed, specifically for what two infections?
upper respiratory tract infections
bronchitis
SCIP which was based on SIP was designed to combat a perceived national crisis, what was that crisis?
preventable surgical site infections
In relation to mortality, spending time in the ICU, and readmission, what were the % risks associated with surgical site infections in the 1990s?
double the risk of mortality
60% increase to spend time in the ICU
and fivefold risk of readmission
The original goal of the SCIP was 25% reduction in surgical site infections by 2010. Was the goal met?
No
However a new goal of 25% was set for 2013 and the goal may have been met with a 20% reduction by 2012.
Patient-related risk factors for surgical site infections include?
extremes of age (less than 5 and greater than 65) poor nutritional status obesity diabetes peri-operative glycemic control peripheral vascular disease tobacco use coexisting infection altered immune response corticosteroid therapy pre-operative skin preperation (hair removal, surgical scrub) length of pre-operative hospitalization.
Institutional variables for surgical site infections include?
surgical experience technique (open vs laproscopic) duration of procedure hospital environment sterilization of equipment peri-operative normothermia
True or False
Good peri-operative glucose control can reduce infection risk.
True
Peri-operative glucose control has been studied predominantly in the cardiothoracic surgery population where it is associated with what % decrease in what kind of infections?
50% decrease in deep sternal infections
Which form of insulin control has been associated with additional reduction in surgical site infections? (cardiothoracic patient presumed)
continuous insulin infusion was associated with additional reduction in surgical site infections compared to intermittent subq injection.
Tell me what type of glucose control post surgery is best for bowel surgery patients?
glucose control of BELOW 200 mg/dL for 48 hours after surgery has shown an infection risk of about 14.3% compared to glucose control of patients greater than 200 mg/dL post surgery with an infection risk of 29.7%.
(the lower glucose post surgery was obviously better for infection risk)
If keeping bowel patients glucose below 200 mg/dL post surgery is good, then can it be concluded that keeping the blood sugar ultra low would be even better? why or why not?
intensive insulin regimens designed to keep blood sugar ultra low have shown higher hypoglycemia and mortality compared to conventional treatment.
(thus ultra low is not better)
Should we even bother telling people to quit smoking before surgery?
smoking cessation is a peri-operative goal. Surgeons and anesthesia providers alike should use the peri-operative setting as a “teachable moment” and even brief smoking cessation CAN reduce infection risks.
what time period of smoking cessation has demonstrated a risk reduction of approximately 50% in infections?
4-8 weeks of cessation
that is basically quitting for a smoker lol
There are 7 SCIP measures laid out for the prevention of surgical site infections, what are they?
- prophylactic antibiotics received within 1 hour prior to surgical incision.
- prophylactic antibiotic selection for surgical patients (the right antibiotic per the surgery being performed).
- prophylactic antibiotic dc’d within 24 hours after surgery end time (48 hours for cardiac patients).
- cardiac surgery patients with a controlled 0600 post-op serum glucose (less than or equal to 200 mg/dL).
- post-op wound infection diagnosed during index hospitalization.
- Surgical patient with appropriate hair removal.
- Colo-rectal surgical patients with immediate post-op normothermia.
Logically hypothermia in the surgical patient will cause what?
peripheral vasoconstriction
decreased wound oxygen tension
recruitment of leukocytes
ALL favoring INFECTION and IMPAIRED WOUND HEALING
Intraoperative warming of patients compared to controls (no intraoperative warming or normal conditions) shows us what about surgical site infections?
when patients were intraoperatively warmed there was an associated decrease of 64% in surgical site infections.
what are some advantages of prewarming patients?
placement of intravenous lines is easier because of vasodilation.
also, active prewarming of 2 hours results in the patient maintaining a core temp. above 36 C for 60 min. under GA with ambient temperatures.
Does long term corticosteroid use contribute to surgical site infections?
This has not been proven. It was for a long time considered a risk factor but there are no studies to definitively prove this claim.
What effect does long term steroid use have on surgical patients?
Long term steroid use has been associated with anastomotic leaks in bowel surgery.
(but not an increase in surgical wound infection as a whole)
If you give a patient a single dose of a corticosteroid for the prevention of N&V, will this increase their likelihood of surgical site infection?
No, there is no evidence to support this claim.
What is the reasoning for SCIP measure 1?
tissue concentration of the antibiotic should exceed the minimum inhibitory concentration (MIC) associated with the procedure and or patient characteristics from the time of incision to the completion of surgery.
(measure 1 is to give prophylactic antibiotics within 1 hour prior to surgical incision.)
Are their any antibiotics that require re dosing during the course of a surgery?
If the antibiotics chosen are short acting and the surgery is long then yes, re dosing may occur.
Why is prophylactic antibiotic use for surgery infection prevention not recommended to go past 24 hours post surgery? (cardiac is 48 hours)
There is no benefit to prolonged dosing but rather an increased incidence of drug-resistance organisms.
The antibiotic chosen should be appropriate for the most likely microorganism related to the procedure and patients characteristics, what SCIP measure is this?
2
If the patient is having a clean elective procedure performed in which no tissue (other than the skin) carrying an indigenous flora is penetrated, will they likely have prophylactic antibiotic use?
No, the risk of routine antibiotic prophylaxis outweighs the possible benefits.
What are the two predominant organisms causing surgical site infections after clean procedures (skin flora)?
Staphylococcus aureus
Staphylococcus epidermidis
In clean-contaminated procedures, including abd procedures and solid organ transplantation, the most common organisms include what?
gram-negative rods and enterococci in addition to skin flora.
(skin flora is S. aureus and S. epidermidis)
Which antibiotics have a recommended re-dosing interval of 6 hours? (2 answers)
Clindamycin (half life = 2-4 hrs)
Cefotetan
Which antibiotics have a recommended re-dosing interval of 4 hours (3 answers)
Aztreonam
CEFAZOLIN (half life =1-2 hrs)
Cefuroxime
Which antibiotic has a recommended re-dosing interval of 3 hours?
Cefotaxime
Which antibiotics have a recommended re-dosing interval of 2 hours? (3 answers)
AMPICILLIN and ampicillin- sulbactam
Cefoxitin
PIPERACILLIN-TAZOBACTAM (Zosyn)
Cipro, Fluconazole, Gentamicin, Levofloxacin, Metronidazole, Vancomycin, Erythromycin, and Neomycin all have recommended re-dosing intervals of what?
NA
(this means that based on the “normal” case length that re-dosing is not recommended, BUT if it is a long surgery then you need to look at the half life and decide from there in order to re-dose)
What is the “interval to re-dose” based on?
re-dosing in the OR is recommended at an interval approx. two times the half-life of the agent in patients with normal renal function.
What are the antimicrobials of choice for surgical procedures in which skin flora and normal flora of the GI and GU are the most likely pathogens?
cephalosporins (most often a cost effective first-generation cephalosporin such as CEFAZOLIN)
What is the likelihood of a patient having a documented IgE reaction to a cephalosporin?
Rare
What is a more likely explanation for a patients reaction to cephalosporins than IgE reaction?
Far more common intolerance such as nausea or yeast infections.
IgE-mediated anaphylactic reactions to antimicrobials usually occur in what time period after dosing and what kind of reactions would you see?
30-60 minutes after dosing and often include urticaria, bronchospasm, and hemodynamic collapse. (life-threatening emergency)
Can cephalosporins safely be given to patients with allergic reactions to Penicillins?
Yes, as long as the reaction of the patient was not an IgE-mediated reaction.
That would mean it could not have been anaphylaxis, urticaria, bronchospasm, or exfoliative dermatitis (Stevens-Johnson syndrome, toxic epidermal necrolysis).
What is the actual % of cros-reactivity with cephalosporins and penicillins?
1%
The original reports of higher cross-sensitivity was due to contaminated drug lots.
What can we do as anesthesia providers to accurately know what a persons true reaction to antibiotic was?
patients should be carefully questioned about the nature of any drug allergy.
Recommended agent (no B-lactam allergy obviously) for cardiac, thoracic, Gastroduodenale, biliary tract, high-risk laparoscopic, small intestine, hernia repair, head and neck that is not clean, neurosurgery, orthopedics requiring an agent, vascular, heart and lung transplant, pancreases and plastics?
(this should tell you to learn the exceptions, and if Hammon is not talking about an exception that you have learned then go with this answer)
CEFAZOLIN
The main recommended agent is cefazolin and at times depending on procedure will have other agents in addition but the common thread is cefazolin. Feel free to learn all details, but the above is the only one I am placing here for simplicity.
Procedures that do NOT require antibiotics? (3 answers)
elective low-risk laparoscopic
Clean head and neck
clean operations involving the hand, knee, or foot not involving implantation of foreign materials.
What is the most common substitute antibiotic agent if someone has a B lactam allergy?
Clindamycin or/then Vancomycin
Appendectomy for uncomplicated appendicitis - what is the recommended agent?
Cefoxitin, cefotetan, cefazolin + metronidazole
Recommended agent for Ophthalmic procedures?
What is the B lactam allergy alternative?
Topical neomycin- polymyxin B-gramicidin or fourth generation topical fluoroquinolones given as one drop every 5-15 min. for five doses.
Addition of cefazolin 100mg b subconjunctival injection or intracameral cefazolin or cefuroxime at the end of the procedure is optional.
There is no B lactam allergy alternative for ophthalmic procedures.
Recommended agent for urologic lower tract instrumentation?
what is the B lactam allergy alternative agent?
Fluoroquinoline, trimethoprim-sulfamethoxazole, cefazolin.
B-lactam allergy = aminoglycoside with or without clindamycin.
Liver transplantation recommended agent?
piperacillin-tazobactam, cefotaxime + ampicillin
If a patient has a documented IgE- mediated anaphylactic reaction then what antibiotics can be substituted in place of the typically recommended agent?
B-lactam antibiotics can usually be substituted with clindamycin or vancomycin.
If MRSA is considered likely then what antibiotic will you use?
Vancomycin
What nasal application has been found to be effective in elimination of MRSA colonization?
Mupirocin
Why is routine prophylaxis with Vancomycin not recommended?
(unless you have documented or highly suspected colonization with MRSA or known IgE-mediated response to B-lactam antibiotics)
risk of inducing hemodynamic instability due to histamine release (red man syndrome), if given rapidly.
also, evidence that vancomycin is less effective than cephazolin in methicillin-susceptible S. aureus.
Clean-contaminated procedures such as colorectal and abdominal surgeries require additional coverage for gram-negative rods and anaerobes in addition to skin flora, what antibiotics would this be?
Metronidazole can be added to cefazolin or cefoxitin, cefotetan, ampicillin-sulbactam, ertapenem, or ceftriaxone.
what is the most frequent complication of prophylactic antimicrobials, including the IV cephalosporins?
Pseudomembranous colitis
Oral antibiotics only vs IV antibiotics prophylactically have shown what?
If oral only is given compared to oral and IV or IV only, the oral only group tends to have higher rates of infections, disproportionately high.
To treat an ongoing infection what is it essential to identify?
identification of the causative organism is essential for appropriate antimicrobial drugs to treat the ongoing infection.
A patient has pneumonia behind a blocked bronchus, what must be done for antibiotic therapy to work in this situation?
the obstruction must be relieved or therapy will not be effective, there will be no response to the antibiotics.
The drug toxicity of hyperkalemia is associated with which antibiotic?
Trimethoprim-sulfamethoxazole
Nearly 80% of nosocomial infections occur in three sites?
urinary tract
respiratory tract
bloodstream
The incidence of nosocomial infections is highly associated with the use of what types of devices? (3 answers)
ventilators
vascular access catheters
urinary catheters
(correlates with the most common sites for infections (resp. tract, bloodstream, and urinary tract))
Intravascular access catheters are the most common cause of what two infections in the hospitalized patient?
bacteremia
fungemia
The organism infecting access catheters most commonly come from what two locations on the catheter?
what does this reflect?
colonized hub or lumen and reflects skin flora (S. aureus and S. epidermidis).
Initial therapy of suspected IV catheter infection usually includes what antibiotic and why?
vancomycin because of the high incidence of MRSA and methicillin-resistant S. epidermidis in the nosocomial environment.
Drug toxicity - allergic reactions is most often associated with which antibiotic(s)?
All antimicrobials but most often with B-lactam derivatives.
does Bowel prep reduce infection?
No
What is the good and bad about vancomycin as an oral antibiotic?
Vancomycin would be active against MRSA but would affect gram-positive flora which plays an important role in resistance to colonization.
Drug toxicity- Nephrotoxicity is due to what antimicrobials? (3 answers)
Aminoglycosides
Polymyxins
Amphotericin B
Drug toxicity- Neutropenia is due to what antimicrobials? (3 answers)
Penicillins
Cephalosporins
Vancomycin
Drug toxicity- Leukopenia and thrombocytopenia (folate deficiency) is due to what antimicrobial?
Trimethoprim
Drug toxicity- Seizures is due to what antimicrobials? (2 answers)
Penicillins and other B-Lactams (high doses, azotemic patients, history of epilepsy)
Metronidazole
Drug toxicity- Neuromuscular Blockade is due to what antimicrobial?
Aminoglycosides
Drug toxicity- GI irritation is due to what antimicrobial?
Tetracyclines
Drug toxicity- Prolonged QT interval is due to what antimicrobials? (2 answers)
Erythromycin
Fluoroquinolones
Drug toxicity- Tendinitis is due to what antimicrobial?
Fluoroquinolones
What five antibiotics are known to have a drug toxicity of Teratogenicity?
Tetracyclines Metronidazole Rifampin Trimethoprim Fluoroquinolones
If a patient has an infected prosthetic then what needs to happen for the antibiotic therapy to be effective?
The prosthetic will need to be removed for therapy to be likely effective.
What three antibiotics are considered safe to use in pregnancy?
Penicillins
Cephalosporins
Erythromycin base
What is the one antibiotic that is labeled as “avoid” during pregnancy?
Metronidazole
Name some antibiotics that should be used cautiously in pregnancy?
Aminoglycosides
Clindamycin
Rifampin
Sulfonamides
Name some antibiotics that are CONTRAINDICATED during pregnancy?
Erythromycin estolate; fluoroquinolones; tetracyclines; trimethoprim
In the elderly patient who is taking antibiotics, what two things might you want to monitor in order to know if they can handle certain antibiotic dosing?
measure plasma concentrations of antimicrobials and monitoring of renal function may be indicated.
What two antibiotics due to their large therapeutic index, obviate the need for significant changes in dosage schedules in the elderly who have normal serum creatinine concentrations?
Penicillins and Cephalosporins.
What two antibiotics may require adjustments in dosing regimens in elderly?
Aminoglycosides and vancomycin
CH2 R group onto a penicillin structure will yield what drug?
Penicillin G
CH2–O R group onto a penicillin structure will yield what drug?
Penicillin V
CH– NH2 R group onto a penicillin structure will yield what drug?
Ampicillin
CH–NH2 and then OH R group onto a penicillin structure will yield what drug?
Amoxicillin
Two CH3O R groups onto a penicillin structure will yield what drug?
Methicillin
Where on the general structure of penicillin do you find the Beta - Lactam Ring?
B-lactam ring is shaped like a square, next to the 5 sided shape that is the Thiazolidine ring.
Penicillins may be classified into subgroups based on what?
their structure
B-lactamase susceptibility
spectrum of activity
The basic structure of penicillins is what?
a dicyclic nucleus (aminopenicillanic acid) consisting of a thiazolidine ring connected to a beta-lactam ring
PCN has a bactericidal action that reflects it’s ability to do WHAT, which is an essential component of cell walls of susceptible bacteria.
interfere with the synthesis of peptidoglycan
Why are some gram-negative bacteria resistant to PCN?
they prevent access to sites where synthesis of peptidoglycan is taking place.
Clinical indications for PCN, Drug of choice for treating?
3 examples (there are more than 3)
Pneumococcal
Streptococcal
Meningococcal
Will PCN treat Gonococci?
Yes, but it has become gradually more resistant to PCN thus higher doses are needed for adequate treatment.
Treatment of syphilis would be?
PCN, highly effective against syphilis.
What is the drug of choice for treating all forms of actinomycosis and clostridial infections causing gas gangrene?
PCN
Transient bacteremia occurs in the majority of patients undergoing dental extractions, emphasizing prophylactic need of what medication for those patient with cardiac issues and tissue implants.
PCN
Transient bacteremia can accompany procedures such as?
T&A, GU, GI, dental extractions, and vaginal deliveries
Penicillin G IV 10 million U contains what?
why is this significant?
16 mEq of potassium
Thus patients with renal dysfunction may result in neurotoxicity and hyperkalemia
If a patient is needing Penicillin G but does not need the dose of potassium bc it could cause demise/risk, what will you use instead?
a sodium salt of PCN G or a similar medication such as ampicillin or carbenicillin can be used.
Can you mix other drugs with Penicillin?
You should not mix other meds with PCN, combinations may inactivate the antimicrobial effects.
Can PCN be administered intrathecally?
Not recommended bc PCN given this route is a potent convulsant!
What will increase the elimination half-time of PCN G approximately 10 fold?
Anuria
How much of PCN is excreted renally in the first hour when given IM?
60-90% IM excreted in first hour
What % of PCN is eliminated by glomerular filtration and what % is by renal tubular secretion.
Approximately 10% eliminated by glomerular filtration and 90% by renal tubular secretion.
What drug can be used to prolong PCN by blocking its renal tubular secretion?
Probenecid
What is the point of procaine PCN?
The mixture is used to try and slow the absorption of PCN and thus prolong the DOA.
Is the renal excretion of PCN slow or rapid?
rapid