Flood Chapter 41 Flashcards
It is estimated that 21% of all prescriptions written for antimicrobials are for
ambulatory patients seen in physicians’ offices with the diagnosis of upper respiratory tract infections or bronchitis.
SCIP stands for
Surgical Care Improvement Project
What are the SCIP measures related to prevention of surgical site infection?
SCIP-inf1: Prophylactic abx within 1hr is incision
SCIP-inf2: Prophylactic abx selection
SCIP-inf3: abx dc’d within 24hr after surg. 48hr CV pts
SCIP-inf4: CV surg pts 6am glu ≤200
SCIP-inf5: Post-op wound infection diagnosed during index hospitalizations
SCIP-inf6: Surg patients with appropriate hair removal
SCIP-inf7: Colorectal surg patients with immediate post-op normothermia
Patient-related risk factors for surgical site infection include?
Extremes of age (younger than 5 and older than 65 years).
Poor nutritional status.
Obesity.
diabetes mellitus and perioperative glycemic control.
peripheral vascular disease.
tobacco use.
coexistent infections.
altered immune response.
corticosteroid therapy.
preoperative skin preparation (surgical scrub and hair removal), and
length of preoperative hospitalization.
Institutional risk factors for surgical site infection include?
Surgical experience and technique (i.e., open vs. laparoscopic).
Duration of procedure.
Hospital environments including sterilization of instruments.
Maintenance of perioperative normothermia.
Perioperative glucose control has been studied predominantly in the cardiothoracic surgery population where it is associated with about a _____ decrease in deep sternal infection.
50%
A meta-analysis of four studies that have assessed the effect of _______ weeks of preoperative smoking cessation demonstrates a risk reduction of approximately__________.
4 to 8 weeks
50%
hypothermia will result in
peripheral vasoconstriction, decreased wound oxygen tension and recruitment of leukocytes, favoring infection and impaired healing.
warming was associated with a ______decrease in surgical site infections.
64%
Active prewarming of volunteers for 2 hours resulted in maintenance of core temperatures above 36°C for 60 minutes of general anesthesia at ambient temperature, whereas core temperatures in unwarmed subjects dropped an average of ________
1.9°C to below 35°C.
Immunosuppression on the basis of long-term use of corticosteroids has been considered a risk factor for surgical site infection, will you give steroids to surgical patients?
There is clear evidence that a single dose of corticosteroid given to prevent nausea and vomiting and reduce pain does not promote infection.
SCIP 1 Antibiotic treatment is not recommended for longer than 24 hours because of an increased incidence of drug-resistant organisms. True/False?
False
This recommendation is based on findings of no benefit to prolonged dosing.
SCIP measure 2 states
The antibiotic chosen should be appropriate for the most likely microorganism related to the procedure and patient characteristics
The predominant organisms causing surgical site infections after clean procedures are
Skin flora (Staphylococcus aureus and Staphylococcus epidermidis).
Most common antibiotic used for cardiac surgery (Table 41-3)
Cefazolin, Cefuroxime.
If allergic to beta-lactam then Clindamycin, vancomycin.
Most common antibiotic used for non-cardiac thoracic procedures (Table 41-3)
Cefazolin, ampicillin-sulbactam.
If allergic to beta-lactam then Clindamycin, vancomycin.
Most common antibiotic used for gastroduodenale procedures (Table 41-3)
Cefazolin
If allergic to beta-lactam then:
Clindamycin/ vancomycin + aminoglycoside/ aztreonam/ fluoroquinolone
Most common antibiotic used for biliary tract open procedures, high risk elective laparoscopic procedures and appendectomy (Table 41-3)
Cefazolin, cefoxitin, cefotetan, ceftriaxone, ampicillin-sulbactam
If allergic to beta-lactam
Clindamycin/vancomycin + aminoglycoside/aztreonam/fluoroquinolone.
Metronidazole + aminoglycoside/fluoroquinolone
Most common antibiotic used for low risk elective laparoscopic procedures (Table 41-3)
none
cephalosporin such as cefazolin are the antimicrobials of choice for surgical procedures in which skin flora and normal flora of the GI & GU tracts are the most likely pathogens. This is because of their?
wide therapeutic index and low incidence of side effects
Patients with documented ____________reaction to cephalosporins are rare and often mistaken for more common intolerances such as nausea or yeast infection
immunoglobulin E (IgE)
IgE-mediated anaphylactic reactions to antimicrobials usually occur ____________ minutes after dosing and often include_____________.
30 to 60 minutes
urticaria, bronchospasm, and hemodynamic collapse.
Grandma had urticaria after taking penicillin, can she get a cephalosporin instead?
Cephalosporins can safely be used in patients with an allergic reaction to penicillins that is not an IgE-mediated reaction (e.g., anaphylaxis, urticaria, bronchospasm)or exfoliative dermatitis (Stevens-Johnson syndrome, toxic epidermal necrolysis)
In patients with documented IgE-mediated anaphylactic reactions, β-lactam antibiotics can usually be substituted with
clindamycin or vancomycin
In patients with MRSA colonization what antibiotic may be considered
Vancomycin
Nasal application of mupirocin has been considered as an alternative and has been found to be effective in eliminating MRSA colonization in adults and children.
Routine prophylaxis with vancomycin is not recommended for any patient population in the absence of?
documented or highly suspected colonization or infection with MRSA (recent hospitalization of nursing home stay and hemodialysis patients) or known IgE-mediated response to β-lactam antibiotics.
The recommendation against routine prophylaxis with vancomycin is due to?
Concerns about selection of resistant organisms.
Its risk of inducing hemodynamic instability due to histamine release (red man syndrome) if given rapidly.
Evidence that vancomycin is less effective than cephazolin in methicillin-susceptible S. aureus
If given rapidly, vancomycin will cause?
Red Man Syndrome- hemodynamic instability due to histamine release
Clean-contaminated procedures such as colorectal and abdominal surgeries require additional coverage for?
gram-negative rods and anaerobes in addition to skin flora.
Metronidazole can be added to __________ in clean-contaminated procedures
cefazolin or cefoxitin, cefotetan, ampicillin-sulbactam, ertapenem, or ceftriaxone
_________with oral antimicrobials has been studied as a potentially less costly alternative
Bowel preparation
What is the most frequent complication of prophylactic antimicrobials, including the IV cephalosporins.
Pseudomembranous colitis
Mechanical bowel preparation alone does not reduce infection, but selective decontamination of the digestive tract with ____________eradicates the colonization gram-negative microorganisms, S. aureus, and yeasts from oral cavity to rectum.
oral topical polymyxin, tobramycin, and amphotericin
Vancomycin would be active against MRSA in selective decontamination of the digestive tract but is not recommended because?
gram-positive flora plays an important role in the resistance to colonization
Which antibiotics are nephrotoxic (Table 41-4)
Aminoglycosides
Polymyxins
Amphotericin B
All antimicrobials can cause allergic reactions but most often seen with? (Table 41-4)
Beta-lactam derivatives
Inhibits platelet aggregation (Table 41-4)
Penicillins in high doses
Causes Prolonged PTT (Table 41-4)
Cephalosporins
Causes Bone marrow suppression (aplastic anemia, pancytopenia) (Table 41-4)
Chloramphenicol
Flucytosine
Linezolid (reversible)
causes hemolytic anemia
Chloramphenicol
Sulfanomides
nitrofurantoins
Primaquine
Causes agranulocytosis
Macrolides
Trimethoprin-sulfamethoxale
Causes leukopenia and thrombocytopenia
Trimethoprin
Causes normocytic normochromic anemia
Amphotericin B
Causes Ototoxicity
Aminoglycosides
Vancomycin (auditory neurotoxicity)
Minocycline (vestibular toxicity)
Causes seizures
Penicillins and other beta lactams (high doses, azotemic patients, history of epilepsy)
Metronidazole
Causes neuromuscular blockade
Aminoglycosides
Causes peripheral neuropathy
Nitrofurantoin (renal failure)
Isoniazid (prevent with pyridoxine)
metronidazole
Causes Benign intracranial hypertension (Pay attention)
Tetracyclines
Causes Optic neuritis
Ethambutol
Causes Hepatotoxicity
Isoniazid Rifampin Tetracyclines (high doses) Beta lactam antimicrobials ( high doses) Nitrofurantoin Erythromycin SUlfonamides
Increased plasma bilirubin concentrations
Quinupristin-dalfopristin
Erythromycin
Causes GI irritation (Pay attention)
Tetracyclines
Causes prolongation of QTc interval (Pay attention)
Erythromycin
Fluoroquinolones
Causes exaggerated sympathomimetic effects in patient s receiving MOI
Linezolid
Causes hyperkalemia (Pay attention)
Trimethoprim-sulfamethoxole
Causes tendinitis (pay attention)
Fluroquinolones
Causes arthralgias and myalgias
quinupristin-dalfopristin
Causes photosensitivity
Sulfonamides
Tetracyclines
Fluroquinolones
Causes teratogenicity(pay attention)
Metronidazole
Rifampin
Trimethoprim
Fluroquinolones
___________ is essential for the selection of appropriate antimicrobial drugs to treat ongoing infection.
Prompt identification of the causative organism
The efficacy of antimicrobial therapy depends on?
drug delivery to the site of infection.
Transport across the blood–brain barrier varies greatly among antimicrobials.
Antimicrobial therapy is more likely to be effective if the infected material (foreign body, prosthesis) is?
removed.
Infections behind obstructing lesions such as pneumonia behind a blocked bronchus can be cured with antibiotics. True/False?
False
It will not respond to antimicrobials until the obstruction is relieved.
80% of nosocomial infections occur in?
urinary tract, respiratory system, and bloodstream
The most common causes of bacteremia or fungemia in hospitalized patients is?
Intravascular access catheters
Initial therapy of suspected intravascular catheter infection usually includes vancomycin because of?
high incidence of MRSA and methicillin-resistant S. epidermidis in the nosocomial environment.
Most antimicrobials cross the placenta and enter maternal milk. True/False?
True
Pharmacokinetics and toxicities in the fetus are often different from those in older children and adults because?
The immature fetal liver may lack enzymes necessary to metabolize certain drugs
Teratogenicity is a concern when any drug is administered during
early pregnancy.
Plasma antimicrobial concentrations may be decreased (10% to 50%), especially late in pregnancy and in the early postpartum period due to?
Increases in maternal blood volume, glomerular filtration rate, and hepatic metabolic activity.
absorption of orally administered antimicrobials in parturients is?
decreased in some parturients due to delayed gastric emptying
Physiologic changes that occur with increasing age can lead to alteration in?
Oral absorption- decreased gastric acidity, reduced gastrointestinal motility.
Distribution- increased total body fat, decreased plasma albumin concentrations.
Metabolism- decreased hepatic blood flow.
Excretion -decreased glomerular filtration rate.
Penicillins and cephalosporins obviate the need for significant changes in dosage schedules in elderly patients who have normal serum creatinine concentrations because?
they have a large therapeutic index
Administration of ___________and ________ to elderly patients may require adjustments in dosing regimens.
aminoglycosides and vancomycin
Favorable intervention to reduce risk of opportunistic infection in HIV patient is?
good preoperative control on an antiretroviral regimen with preserved T4 cell counts.
The basic structure of penicillins is
a dicyclic nucleus (aminopenicillanic acid) that consists of a thiazolidine ring connected to a β-lactam ring.
The penicillins may be classified into subgroups because of their
structure, β-lactamase susceptibility, and spectrum of activity.
The bactericidal action of penicillins reflects (MOA)
interferes with the synthesis of peptidoglycan, which is an essential component of cell walls of susceptible bacteria. Penicillins also decrease the availability of an inhibitor of murein hydrolase such that the uninhibited enzyme can then destroy (lyse) the structural integrity of bacterial cell walls.
Cell membranes of resistant gram-negative bacteria are in general resistant to penicillins because?
they prevent access to sites where synthesis of peptidoglycan is taking place.
What is the drug of choice for treatment of pneumococcal, streptococcal, and meningococcal infections.
penicillins
What are the 3 cephalosporin which can take care of pseudomonas ?
3rd generation - Ceftezidime
4th generation - Cefepime
5th generation - Cefolazane/Tazobactam
Which cephalosporins have anaerobic coverage?
2nd generations : Cefuroxime and Cefoteton
And
5th generations: ceftolazane/ Tazactam & Ceftoraline
Anaerobic bacteria are commonly found intraabdominal
What are 1st generation cephalosporins and describe their properties
Cefazolin( Ancef ), Cephalexin ( Keflex)
Great for skin and soft tissue infections
-Cidal by inhibiting enzymes in the cell wall of the bacteria = no bacterial cell synthesis
NO anaerobic coverage *
Great Gram + coverage ( i.e. Staph and Strep)
Some Gram - coverage ( i.e E-Coli, Proteus, Kiebsiella)
Think Skin and soft tissue infections
Renal dosing is needed with cephalosporins bc they are primarily eliminated in the urine . Except which 2 :
Ceftriaxone ** and Cefoperazone ( don’t think you have to know that one )
Those have significant elimination in the bile
Which is the only cephalosporins with MRSA coverage ?
5th generation : Ceftaroline ( Teraflo) , the one and only .
Contraindication with ceftriaxone ( Rocephin)
Can’t give with calcium in the same IV tubing, will cause calcium salt.
Cefepime aka Maxipime , class, generation and coverage
4th generation cephalosporin
GREAT Gram + and GREAT gram + also bonus of Pseudomonas coverage
No anaerobic coverage
Think all kind of serious infections
Cefazolin dose
Adults: 2g, 3g if>120kg
Pediatrics: 30mg/kg
Redose after 4hrs
half life 1-2.2
Ceftriaxone dose
Adults: 2g
Pediatrics: 50-75 mg/kg
Do not redose
half life 5.4-10.9hrs
Cipro dose
Adults: 400mg
Pediatrics: 10mg/kg
Do not redose
half life 3-7hrs
Clindamycin dose
Adults: 900mg
Pediatrics: 10mg/kg
Redose after 6hrs
half life 2-4hrs
Gentamicin
Adults: 5mg/kg(Dosing weight
Pediatrics: 2.5mg/kg(dosing weight)
Do not redose
half life 2-3hrs
Levofloxacin
Adults: 500mg
Pediatrics: 10mg/kg
Do not redose
half life 6-8hrs
Metronidazole
Adults: 500mg
Pediatrics: 15mg/kg
Do not redose
half life 6-10hrs
Vancomycin
Adults: 15mg/kg
Pediatrics: 15mg/kg
Do not redose
half life 4-8hrs
Penicillin is the drug of choice for treatment of
pneumococcal, streptococcal, and meningococcal infections.
all forms of actinomycosis and clostridial infections causing gas gangrene.
_____infections have gradually become more resistant to penicillin, requiring higher doses for adequate treatment.
Gonococci
highly effective drug for treatment of syphilis
Penicillin
Penicillin is of value to patients with rheumatic fever because?
Prophylactic administration of penicillin is highly effective against streptococcal infections.
Transient bacteremia occurs in most patient undergoing
dental extractions
tonsillectomy
operations on the genitourinary and gastrointestinal tracts,
vaginal delivery.
Transient bacteremia is prevented by prophylactic penicillin for dental procedures most importantly in which patient population?
patients with congenital or acquired heart disease or tissue implants undergoing dental procedures.
Administration of high doses of penicillin G IV to patients with renal dysfunction may result in
neurotoxicity and hyperkalemia (10 million U of penicillin G contains 16 mEq of potassium).
substitute with a sodium salt of penicillin G or a sodium salt of a similar penicillin, such as ampicillin or carbenicillin.
Can you give a patient Intrathecal penicillin?
NO
Intrathecal administration of penicillins is not recommended because these drugs are potent convulsants when administered by this route. Furthermore, arachnoiditis and encephalopathy may follow intrathecal penicillin administration.
Other drugs should not be mixed with penicillin because?
the combination may inactivate the antimicrobial.
Penicillin elimination
Approximately 10% is eliminated by glomerular filtration, and 90% is eliminated by renal tubular secretion.
Anuria increases the elimination half-time of penicillin G approximately
10-fold.
Methods to prolong the duration of action of penicillin include
the simultaneous administration of probenecid, which blocks the renal tubular secretion of penicillin.
IM injection of poorly soluble salts of penicillin, such as procaine or benzathine, delays absorption and thus prolongs the duration of action.
Procaine penicillin contains
120 mg of the local anesthetic for every 300,000 U of the antimicrobial.
The major mechanism of resistance to the penicillins is
bacterial production of β-lactamase enzymes that hydrolyze the β-lactam ring, rendering the antimicrobial molecule inactive.
______are not susceptible to hydrolysis by staphylococcal penicillinases that would otherwise hydrolyze the cyclic amide bond of the β-lactam ring and render the antimicrobial inactive.
Methicillin (dimethoxybenzylpenicillin), oxacillin, nafcillin, cloxacillin, and dicloxacillin
Penetration of ________ into the central nervous system (CNS) is sufficient to treat staphylococcal meningitis.
nafcillin
Parenteral methicillin has largely been superseded by?
oxacillin and nafcillin.
Hemorrhagic cystitis and an allergic interstitial nephritis (hematuria, proteinuria) may accompany administration of?
methicillin.
Hepatitis has been associated with high-dose ______ therapy. (Penicillins)
oxacillin
Renal excretion of _________ is extensive. (Penicillins)
methicillin, oxacillin, and cloxacillin
More than 80% of an IV dose of ________________is excreted in the bile, which may be an advantage when high-dose therapy is necessary in a patient with impaired renal function.
nafcillin
__________ unlike methicillin, are relatively stable in an acidic medium, resulting in adequate systemic absorption after oral administration.
Oxacillin and nafcillin
_____________ are available only as oral preparations and may be preferable because they produce higher blood levels than do oxacillin and nafcillin.
Cloxacillin and dicloxacillin
Broad-spectrum penicillins have a wider range of activity than other penicillins, being bactericidal against ?
gram-positive and gram-negative bacteria
Broad-spectrum penicillins such as ampicillin, amoxicillin, and carbenicillin are all inactivated by penicillinase produced by certain gram-negative and gram-positive bacteria. True or false?
True
Ampicillin (α-aminobenzylpenicillin) has a broader range of activity than penicillin G. T/F?
True
Among the penicillins, __________ is associated with the highest incidence of skin rash (9%), which typically appears 7 to 10 days after initiation of therapy.
ampicillin
Ampicillin spectrum encompasses not only pneumococci, meningococci, gonococci, and various streptococci but also______________
a number of gram-negative bacilli, such as Haemophilus influenzae and Escherichia coli.
Ampicillin is well absorbed after oral administration because?
It’s stable in acid
Approximately 50% of an oral dose of ampicillin is excreted unchanged by the kidneys in
the first 6 hours, emphasizing that renal function greatly influences the duration of action of this antimicrobial.
______________ also appears in the bile and undergoes enterohepatic circulation.
Ampicillin
Skin rash after a dose of ampicillin mostly represent true allergic reactions. True/ False?
FALSE
Many of these rashes are due to protein impurities in the commercial preparation of the drug and do not represent true allergic reactions.
Amoxicillin is chemically identical to ampicillin except for_______
an −OH substituent instead of an −H on the side chain.
Its spectrum of activity is identical to that of ampicillin, but it is more efficiently absorbed from the gastrointestinal tract than ampicillin, and effective concentrations are present in the circulation for twice as long.
Amoxicillin
Penicillinase-Susceptible Broad-Spectrum Penicillins (Second-Generation Penicillins) include
ampicillin, amoxicillin, and carbenicillin
Extended-Spectrum Carboxypenicillins (Third-Generation Penicillins) include
Carbenicillin
________ results from the change from an amino to carboxy substituent on the side chain of ampicillin.
Carbenicillin (α-carboxybenzylpenicillin)
The principal advantage of carbenicillin is
its effectiveness in the treatment of infections caused by Pseudomonas aeruginosa and certain Proteus strains that are resistant to ampicillin.
Carbenicillin is penicillinase susceptible and therefore ineffective against most strains of _________
S. aureus.
Carbenicillin is not absorbed from the gastrointestinal tract; therefore, it must be administered parenterally. T/F
true
The elimination half-time of carbenicillin is approximately 1 hour and is prolonged to approximately _________ hours when there is hepatic or renal dysfunction.
2 hours
Approximately 85% of the unchanged drug is recovered in urine over 9 hours. __________ by delaying renal excretion of the drug, increases the plasma concentration of carbenicillin by approximately 50%.
Probenecid
Congestive heart failure may develop in susceptible patients in response to acute drug-produced sodium load by which drug
Carbenicillin
The sodium load administered with a large dose of carbenicillin (30 to 40 g) is considerable because greater than 10% of carbenicillin is sodium (about 5 mEq/g).
Hypokalemia and metabolic alkalosis may occur with Carbenicillin because of?
obligatory excretion of potassium with the large amount of nonreabsorbable carbenicillin.
___________interferes with normal platelet aggregation such that bleeding time is prolonged but platelet count remains normal.
Carbenicillin
Extended-Spectrum Acylaminopenicillins (Fourth-Generation Penicillins) include
mezlocillin, piperacillin, azlocillin
Drugs with the broadest spectrum of activity of all the penicillins are
Acylaminopenicillins (mezlocillin, piperacillin, azlocillin)
Like the carboxypenicillins, the acylaminopenicillins are derivatives of?
ampicillin.
_______, _________and ________- are β-lactam compounds that have little intrinsic antimicrobial activity.
Clavulanic acid, sulbactam, and tazobactam
Clavulanic acid is available with oral amoxicillin and parenteral ampicillin preparations have been combined with?
sulbactam.
_____________ like the penicillins, are bactericidal antimicrobials that inhibit bacterial cell wall synthesis and have a low intrinsic toxicity.
Cephalosporins,
Cephalosporins antimicrobials are derived from
7-aminocephalosporanic acid.
Individual cephalosporins differ significantly with respect to?
the extent of absorption after oral ingestion
severity of pain produced by IM injection
protein binding.
Resistance to the cephalosporins, as to the penicillins, may be due to
an inability of the antimicrobial to penetrate to its site of action.
cephalosporinases (β-lactamases) produced by bacteria, which disrupt the β-lactam structure of cephalosporins and thus inhibit their antimicrobial activity.
IV administration of any of the cephalosporins can cause _________
thrombophlebitis.
_________ metabolites of cephalosporins can occur and are associated with decreased antimicrobial activity.
Diacetyl
A positive Coombs’ reaction frequently occurs in patients who receive large doses of
cephalosporins.
Hemolysis, however, is rarely associated with this response.
Nephrotoxicity owing to cephalosporins,________ compared to aminoglycosides or polymyxins.
is less frequent
The incidence of allergic reactions in patients being treated with cephalosporins ranges from
1% to 10%.
This antimicrobial is an exception among the cephalosporin family due to its nephrotoxicity
cephaloridine
The majority of the cephalosporin allergic reactions consist of?
cutaneous manifestations, which occur 24 hours after drug exposure.
patients who are allergic to one cephalosporin are likely to be allergic to others because?
Because the cephalosporins share immunologic cross-reactivity
The possibility of cross-reactivity between cephalosporins and penicillins seems to be very infrequent, and cephalosporins are often selected as alternative antimicrobials in patients with a history of penicillin allergy. T/F
True
Like the newer penicillins, the new cephalosporins have an extraordinarily broad spectrum of antimicrobial action but are expensive. T/F
True
The most common adverse reaction to β-lactam antimicrobials is?
Hypersensitivity
Most often, the allergic response to cephalosporins and penicillins is a delayed reaction characterized by
a maculopapular rash and/or fever.
Manifestations of immediate hypersensitivity may include
laryngeal edema, bronchospasm, and cardiovascular collapse.
