Class 13 Deck 1 Flashcards
What is the difference between bacteriocidal and bacteriostatic?
- Bacteriosidal = Kill bacteria
- Bacteriostatic = Inhibit bacteria growth
What is the Minimum Inhibitory Concentration (MIC)?
-Lowest concentration of antibiotic required to inhibit growth
What is the Maximum Bactericidal Concentration (MBC)?
-Concentration required to kill 99.99% of the inoculum
What is concentration dependent killing?
-Antibiotics that increase extent of killing with increased concentrations (aminoglycosides)
What is time dependent killing?
-Clinical effectiveness is related to duration of exposure not greater concentrations.
What is the post antibiotic effect?
-Antibiotics continue to suppress bacteria growth after drug is no longer detectable
Post antibiotic effect (PAE) can be decreased in what type of environment?
-Acidic (infected)
During the PAE phase, bacteria are more susceptible to killing by ______.
Leukocytes (body doing the work)
Antibiotics with concentration-dependent killing and significant PAEs, it is more important to have very _____ _____ and allow the ______ to decrease to less than MIC (Let PAE do the work) this is the basis daily dosing of what drug?
- High Peak
- Trough
- Amoniglycosides
Sometimes the presence of an ______ may allow a drug to ______ when it otherwise wouldn’t. What is an example?
- Infection, penetrate
- Meningitis
What local factors may modify the efficacy of the drug?
- Poorly drained infection (Low ph/O2 tension/ pus)
- Mixed infection
- Infected hematoma
- Foreign body
Food or substances containing what can alter GI absorption?
-Divalent metal ions
What are the mechanisms for acquired resistance?
- Decreased permeability
- Increased effux pumps
- Inactivation
- Modification of antimicrobial target
- Development of pathways that bypass target
What is increased effux?
-Drug gets into cell but bacteria pumps it out.
What drugs are effected by effux?
- Macrolides
- Fluroquinolones
- Beta Lactams
What is the predominant mechanism of acquired resistance of antimicrobials?
-Inactivation
Beta lactams are inactivated by what?
-Beta lactamases
Modification in the penicillin binding proteins account for methicillin resistance in _______ and penicillin resistance in _______ and _______
- staphylococcus
- pneumococci and enterococci
What are the three reasons to use multidrug therapy?
- Polymicrobial infections
- Emergence of resistance
- Synergy
What broad spectrum antibiotics can cover multiple organism infections?
- Ampicillin-sublactam
- Imipenen-cilastin
How should resistance be inhibited? What is an example of this?
- Administration of 2 antibiotics w/ different MOAs
- TB
What are the synergy combination responses?
- Antagonism (1+1=0.5)
- Indifferent (1+1=1)
- Inbetween (1+1=1.5)
- Additive (1+1=2)
- Synergistic (1+1=3)
Treatment of infection with antimicrobial use can be narrowed down to what three things?
- Delivery of drug to infection
- High enough concentration
- Sufficient time to inhibit/kill bacteria
What 5 infections require bactericidial therapy?
- CV infection (endocarditis)
- Meningitis/Cerebral abscess
- Neutropenic patients
- Osteomylitis
- Prothesis/vascular access infection w/o removing device
What 3 things should be known to make proper therapy choices?
- Patient
- Invading microbe
- Antimicrobial agents
What information should be known about the patient?
- Where exposed
- Previous antibiotic treatments
What are some examples of impaired host defenses against SPECIFIC INFECTION types?
- Anatomical (ulcerations)
- Secondary (Neutropenia, aspleenia, Malignancy, HIV, immunosupressant therapy)
What can increase a patients risk for infection complications? and what should you consider?
- Prothesis or foreign bodies (Heart valves, grafts)
- front loading antibiotic therapy
How are preggos at risk for infection complications?
- Pharmacokinetics are altered
- Increased VD and GFR
- Little or not safety data on ABX
What ABX is OK for preggos?
- PCN, Cephalosporins and erythomycin
- except ticarcillin
What ABX should be used only if necessary in preggos?
- Aminoglycosides (cranial nerve dysfunction)
- Isoniazid (Retardation, myoclonus, seizures)
What 6 drugs should be avoided in preggos?
- Metranidazol
- Ticarcillin
- Tetracyclines
- Trimethoporin
- Rifampin
- Fluroquinolones
What does tetracyclines do to fetus?
- Fatty necrosis of liver
- Panreatitis
- renal innjury
What can increase risk of taking a specific ABX drugs?
- Previous reaction to the ABX
- Decreased renal/hepatic function
Decreased renal function can have what effect with aminoglycosides? PCN/Imipenem? Ticarcillin/Mezlocillin/Pipercillin?
- 8th cranial nerve (ototoxicity)
- Seizures
- Bleeding (platelet dysfunction)
80% of all nosocomial infections occur where?
- Resp system (24%) from vents
- Blood (17%) from IV catheters
- Urniary tract (36%) From foleys
IV catheters are a common cause of what?
- Bactermia
- Fungemia
How is catheter infection defined?
- 1 positive blood culture from cath and perpherial site
- Clinical manifestation of infection
- No other apparent source
What central line sites are at greatest risk for infection?
Femoral > I.J. > Subclavian
What is the initial therapy for catheter related infections? and why?
- Vancomycin
- High prevalence of MRSA and staph epidermidis in noscomial infections
When would gram negative rod coverage w/ catheter related infections be appropriate?
- infection at other body site
- CV instability
How should staph epidermidisa and enterocococcus be treated?
Remove catheter and short course of ABX
Staph aureus often disseminates and can cause what destructive infections?
- Osteomylitis
- Endocarditis
How should staph aureus be treated?
- Prolonged ABX therapy
- Look for metaststic lesions
Candida fungemia requires what?
- Looking for metastatic infections
- If non found remove cath and use fluconazole
What drug is usually used for surgical prophylaxis? and why?
-1st gen cephalosporin (cefazolin)
What are the 4 would classes?
- Class I: Clean
- Class II: Clean-Contaminated (surgery in area known to have bacteria)
- Class III: Contaminated (Break in sterile technique)
- Class IV: Dirty-Infected (infection before surgery)
What is the most common infection from clean wounds? and what should be administered?
- Staphylococcal
- Some do not require prophalyxis
Clean-Contaminated and contaminated requires what? (including hyst and urinary tract procedures)
Prophylactic ABX
Patients w/ UTI’s should have what ABX?
-ABX against gram negative bacilli (Fluorquinolones, aminoglycosides, 3rd gen cephlasporins)
Biliary tract and urinary tract should have what type of ABX?
- Ampicillin-sublactam
- Piperacillin-tazobactam
What is the SCIP mandate for prophylactic ABX?
-All patients 18 and up have parenteral ABX
-Must be administered w/i one hour prior to incision
(fluroquinolone & Vanco w/i 2 hours)
Bacteremia resulting from ______ is much more likely to cause IE than from bacteremia associated with a dental, GI, or GU procedure.
-Daily activities
What are the new guidelines for infective endocarditis?
-ABX Prophylaxis for those with the highest risk of adverse outcomes should they develop IE, rather than those at highest risk of developing IE.
What 4 cardiac conditions are at greatest risk for adverse outcomes with IE?
- Prosthetic cardiac valve
- Previous IE
- Congentital heart disease
- Cardiac transplant who develop valvulopathy
What procedures have increased risk for developing bacteremia subsequent IE?
- Dental
- Respiratory tract procedures
What bacteria is the most common cause of endocarditis?
-Streptococcus viridans
What is the preferred prophylaxis for dental or respiratory procedures?
- PO amoxicillin
- IV ampicillin/cefazolin in unable to take PO
- PO cephalexin/Clindamycin/Azithromycin if allergic to PCN
Post op pneumonia is NOT community acquired and usually needs what ABX?
-Clindamycin (similar to erythromycin but more active against anaerobes)
What is the leading cause of noscomial GI infection?
-C-Diff
What causes C-Diff?
- ABX by altering normal bowel flora
- Enterotoxin A and Cytotoxin B
What is the ABX of choice in C-Diff?
- Metronidazole
- Vanc if not responsive to metronidazole
